I've just binge watched some of your technical videos regarding Bromptons, and I must say I'm baffled by the quality of your explanation as much as your production value, which very much go hand in hand. Thank you for putting out quality content, it goes a long way
hello, we, 2 of us who are considering foldings bikes, brompton, for activity similar to your channel, although for us, just starting, watched this video, and then several more. I KNEW Brompton offered multiple gear options, and methods. I KNEW could change the overall standard gear ratio by change a major gear. I KNEW about overall idea of gears being useful for hills, vs flat, of range of gears, of steps, ratio, between gears. YET, I DID NOT UNDERSTAND on any deep level, any of this. Just sort of that existed. Your VIDEO made all of this so clear, on not just Brompton, yet across ALL bikes. I have a bike, I know how to shift, I feel the impact of various gears, yet never really understood at level that I now do. All in under 9 minutes. Stunned. Upvoted, and subscribed!
Riding a bike and understanding it in detail was really a new concept. If the second hand market here were popular or less unregulated, I would probably consider seriously too. It's excellent for storage and portability.
I think this is extremely helpful! Your thoughtful visuals, explanatory script and advice are simply a level above what I've seen elsewhere. Thank you so much!
The next version of this video will include the 12-speed that was released in Jan 2024. Meanwhile, this video on the subject provides the main details: th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
As an owner of the former Top, SuperlightM6LXBrompton, I have used it during vacations on our only Danish, Rocky Island of Bornholm, and it has a serpentine road going up to a former lighthouse. As an elderly, too heavy man in a bad shape I had to walk once in a while, going up and also to pass the several "cattle prevention bars", crossing the road at intervals, some with a self closing gate to the side. My 6 gears came in fine but wasn't even enough for the job! I do also own a 33 gears carbon MTB, with gears which are so low that I can't even start on a flat road in them, but going up an extreme hill in a wood, they are fine!! Finn. Denmark
What a fabulously informative and well-explained video! I was almost ready to buy a 4-speed P-line Brompton for touring, but now think the 6-speed C-line will probably be better.
Probably the best presentation I've seen on all current Brompton gear ratios (including the new T line which was what I was looking for). Better than my spreadsheet and coming to the same conclusions on choice - i.e. 6 speed classic with standard/reduced chainring is best for touring/hilly terrain. I would however like more gears to reduce the jumps and to remove the compromise of having to either pedal furiously or with a slower less efficient cadence in order to maintain a particular speed, something which the new 4 speed doesn't address.
Adding a 3rd sprocket or upgrading to a dual-chainring could be solutions to improve range and gear gap (ref. our video th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html )
Thank you so much for this informative video! Very helpful indeed! I will definitely go for the C-Line and choose my favourite Cloud Blue Brompton! M6L 😊❤
Since this video was published, Brompton announced the release of 12speed versions for the C Electric, P Electric, P-Line and T-Line. Here's our video on the subject: th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
Pam and Gilbert Love the video. Fantastic comparison and very easy to see the difference on gearing. I had the opportunity to ride the new T line, it does lack gears for our touring purposes, but love the quick and staight response to pedal. Once more congrats, love it!
Hi Chris, we did see your NYC video(s) concerning the T-Line. What a great experience it must have been riding it. Brompton did sacrifice gear range when they decided to go for a such a lightweight solution. Great for a quick commuter but limited as far as touring goes.
@@2Bikes4Adventure Yes, it is an amazing bike, but not for us that like to use it on biketouring going uphill and full of bags. I love these videos that scientifically explain the reason for things. You guys are great! I won't be able to participate to the TB5BNY this year, hope to meet you next year 👍🏻😊🚵♀️
@wanderingsofalanandcaz We do have a 44T chainring on our M6R. As for the gradient it can tackle, it will depends on fitness level. We would refer you to the graph at 06:43 for a rough estimate: About 90 min on a 7% grade, 45 min on a 10% grade and 1 min at 20%.
Great info! In Singapore and some Asian countries we have many different brands of ‘Brompton clone’ so call trifold bikes that comes with default 46 or 48T chainring running on the SFR3 internal hub and 2 or 3 external sprockets, giving a 6 or 9speed configurations.
Neat and well-explained. I recently upgraded my three speed to a 5xspeed just so that I would get a little bit more on the lower and higher end of the gear range. 256% as a whole lot better than the previous. But I can certainly see where others with the three speed have gone to the 44 tooth to get some of the same low-end gains.
@@2Bikes4Adventure mine was the result of getting a custom wheel made by BrommiePlus. It doesn’t look like it was all that complicated though. I wanted the 8spd SA, but that’s no where to be found anymore. I’m running the 50t up front and 13t on the rear, gear inches (according to their chart) are 40/48/64/85/102 for 256%, which is definitely in the “comfy” range according to your video
Hi, wonderful and instructive videos. Could you please reveal how you make them? Or at least some essential hints for the animations? Keep on, I’m delighted!
My advise for gear selection: 1. Do you climb hills, strong head winds and are you not as strong? Buy the 6 gear system. 2. Do you ride in the city, less then 5 km/ 3 miles? The 4 gear system will do if you are not so strong. The 2 or 1 gear if you are strong. The 3 gear is not useful, the gears are spaced too far apart. So the gear 3 you will seldom use. Unless you change the sprocket to a bigger sprocket or a smaller chain ring, so you can use gear 3 as well. 3. Do you use your Brompton for touring with luggage. Buy the 6 gear.
I wish Brompton did a 39T chainring as I never use the 3 High gear. I had the thirdparty 39T but it did not fit the Shimano crank I installed to my M6 so I reverted to the 44T.
Massively informative as usual.. Really going to have to look replacing the internal hub on my 3 speed as the weight to gearing ratio is the worst out of all of them. Unsure if I go for a aftermarket derailleur solution or go for a 6 speed hub. Really its naughty that brompton make two different internal hubs that weigh roughly the same but then force you to buy the BWR to get the two sprockets rather than just putting it on both models which gives you the chance to upgrade. Guess they need some incentive for people to go to the 6 speed as a default..
The dual-drive 6 speed (using the BWR) was a stopgap solution following the demise of the Sturmey-Archer 5 speed hub. Unfortunately, no better solution has been put forward.
@Wildefyr I can recommend the 5spd hub. Recently went from the 3spd to 5spd and having the extra lower and higher have been quite nice. I feel the 3spd w/50t is really not all that bad. But I did need the occasional speedy or “nah, can I get lower” kind of gearing w/o changing the middle. This has been great, despite the weight. Got it at BrommiePlus.
A nice explanation, particularly of the effect of varying power output on hill climbing - very good to relate this to gear choice as well. One question - am interested in your foot position on the pedals. We are normally taught to use the forefoot (or at least I was!), but you are using your mid foot on the pedal. It would be helpful to know why - perhaps I am doing it wrong?
While it is usually accepted that positioning the ball of the foot over the pedal pivot is optimum, some research has found that it may not be critical (www.researchgate.net/publication/6886747_Is_economy_of_competitive_cyclists_affected_by_the_anterior-posterior_foot_position_on_the_pedal). Our approach is less scientific and more aimed towards “do whatever feel right”. So, as the day progresses, we are likely to move our feet position slightly depending on the level of effort required (and fatigue level). It may not be always the most optimum configuration, but than again, we are not in it for the performance aspect.
Fab video thank you! Perhaps a further consideration if cycling in muddy or off-road conditions is that a hub gear system is less likely to get ‘stuck’ than derailleur, particularly when it’s so very close to the ground?
Excellent video. When I was riding my Brompton M6R with 50T on the hill with 10%, I know it’s time to get a 44T. Just wonder what will the curve be at 6:31 when using 50T, how long does it takes for people to be exhausted with a 50T🤔🤔? And I guess also having a 55/34 traditional crankset for T-line probably will be an excellent option to turn it to an amazing bike with wider range, lightweight and performance. Thank you for your wonderful video again!
The graph at 6:31 is for the default chainring configuration (50T for 1, 3, 4 and 6 speed, 54T for 2 speed). At 6:41, we changed to 44T for the 6 speed only. A dual chainring (54/34) would indeed be a inexpensive way to improve the gearing range.
Awesome, I wanted to look up your previous gearing video as my brompton tour in the hills did not go as planned and I was curious if I should go with 44t or maybe check for even smaller 3rd party options. Thanks for that perfect timing!
I ordered myself a 40t H&H Chainring. Will let you know how it goes. I was tempted to even get myself the three sprocket external upgrade, but one thing at a time :)
@@2Bikes4Adventure Thanks! Exactly my thought - since the part is for the Brompton I hope the H&H one fit nicely onto the spider cranks and I hope on the long end it will do around 30kph with my normal cadence (ritzelrechner at least said so) Anyways thanks for offering to look into 3rd party gearing options. There is crazy stuff out there (schlumpf, rohloff, front foot derailleurs) but all fairly low volume with limited information. For me this is a bit too custom as I want my brompton to be reliable
Awesome video. I like that you actually share how a gearing ratio could affect a climb. I wonder if one could do aftermarket modification from 44T chainring to a smaller 36T or 34T for better climbing experience? Many thanks.
This was really educational on gear inches and leverage. It's been helpful from your other videos combined. I checked the single speed line was 50T on its formal website. For the last part on a 4.5% slope (equal to 22:1), how hard could that be for an average-fit person close to 60? Thanks.
According to the graph at 6:21, a 70Kg (young) adult cycling a single speed T-Line at 60rpm on a 4.5% slope would need a break after approximately 15 minutes. Assuming the same body mass, expect about 10% drop in performance for every decade above 30 years old. So, a 60 years old cyclist would likely stop after 10 minutes or so on the same slope.
Thank you - very useful! One update I notice on the Brompton support website, they show the 4-speed has a 56T option now which brings the top gear on the 6 speed closer to the normal 3-speed: 6.74m in the top gear.
I have got a 6speed 44T equipped, but the two highest speeds are anyway too strong to push.... I hope Brompton would realize a 39T-40T in the future.....
I agree, even downhill 3+ or sometimes 3- feels just too fast for this little bike. For me at least, if someone likes to go with 54t for land speed records, thats cool too
@@2Bikes4Adventure the upgrade you told is possibile only with the old Brompton crankset, which had a standard 130 mm BCD, and, for example, you can fit whatever Shimano chainring 39T; models after 2017 though, have got a new personalized (very odd 😏) crankset with 124mm BCD, so you are obliged to use only Brompton components, and the smallest chainring made by Brompton is 44T... I'd had to buy on line a second hand pre-2017 crankset is England... (I'm Italian)🇮🇹😄
Interesting upgrade. The total gear range would increase from 164% to 191% , providing a lower first gear and faster 4th gear. There would be a very noticeable gap between the 2nd and 3rd gear however. You may want to confirm your favorite cadence would not be affected by this gap.
@@2Bikes4AdventureIf I change the p line rear to 11-13-17-21 what would the gear range % be with either the 50 or 44 chainring? I’m thinking of improving it for climbing but not losing too much top end speed. Thanks.
I checked T line on Brompton's website, and the only 2 models available have gears… I'm looking for a model to carry on the bus daily, A line 3 gears seem interesting, despite the Dahon Marine D8 looking more attractive…
Thank you for your wonderful illustration! May I seek your advice: currently running a 54T 3speed SA for fitness riding (20-45km, x 2 per week, average 22km/hr over 1-2hrs) at relatively even terrain (parks & road) I am keen to get the P line to improve my performance (to cycle further & longer & perhaps fill the gap of a missing gear (betw 2nd & 3rd) when fatigue sets in. However, after watching your video & realise the 177% vs 164% gearing range, I am a tad hesitant about the earlier intention. Would love to hear your opinion with your vast experience! Thank you ;)
@eugenetmy, the excitement of owning a brand new bike is not to be ignored, but in this particular case, the price of the 4th gear will be significant. If budget is not an issue, I would go for it (and probably consider a 3rd party 130BCD 56T chainring to shift the gear range upward). Once you have your new P-Line, you could always sell the old 3 speed to help finance the new acquisition although there is nothing wrong with owning more than 1 folding bike (we own 10). On the other hand, if cost is an issue, a cheaper option would be to upgrade your 3 speed to a 5 speed hub. The gap between the 4th and 5th gear will be 18%, the same as the gap between the 3rd and 4th on the P-Line. Furthermore, the total range is 225% (vs 164%). True, the bike will be heavier than the P-Line, but this upgrade would probably cost 1/10 the price of purchasing the new bike. Enjoy your Brompton (whichever model or setup you choose).
I got a C Line Urban for my commute to work. My commute is less than 3km, and there's only one hill of any significance; it's less than 250m, and depending on the stoplight at the beginning, I can generate enough momentum to fairly easily handle the first 1/3 of the hill. So for me, the C Line Urban was the perfect solution. That being said, I come from a road cycling background, and am used to covering distances on the road much faster; I tend to turn taller gears with relatively lower cadence. Do you think upgrading to a 56t chainring (I believe my bike came with a 54t ring) would make a noticeable difference?
Upgrading the chainring from 54T to 56T and 16T to 17T would both make you marginally faster (1km/h at 70rpm in 2nd gear) and provide better hill climbing performance in 1st. It’s a low cost DIY upgrade that can be easily reversed if you don’t like the end result.
Hi, I have recently discovered your videos and I was impressed by the knowledge and the way you explain things. I've just bought a Brompton P Line (because my first priority is the weight and couldn't find the t line anywhere) and I find that the gear range is too narrow for me. I often find myself frustrated when I can't take advantage of a downhill to reach full speed. I was thinking of the following options: 1. (ideal) Increase the number of sprockets (e.g. 5 or 6 total sprockets) to increase the range. I guess I would have to choose sprocket sizes that make sense, in order to cover the whole desired range (preferably similar to the 6 speed brompton). You think it would be possible? Would it require to make any modifications to the rear triangle (e.g. widen it) ? what would be the most lightweight way to do it? 2. (good) Keeping the number of sprockets the same (i.e. 4) but choose different sizes so as to increase the range. Would that be possible? and what kind of range do you think I could reach, keeping a satisfactory overlap between the four gears (as per your video) ? What would be the most lightweight option here? 3. (least preferable) If not possible to change the range without adding considerable weight or irreversibly altering the frame, perhaps I should shift its current range upwards? Would getting a 54T chainring mean that I could go faster downhill but would have to put more effort while climbing uphill? Thanks in advance!
Increasing the gear range on the standard 4 speed P and T-Line will likely be a hot subject in the coming months 1. 3rd parties started offering upgrade kits like this one: www.fantastic4toys.com/collections/brompton-upgrade-parts/products/thx4ride-7-speed-kit-set-for-brompton-bicycle-p-line 2. Some P-Line owners report having no problem replacing the first gear with a sprocket bigger than the standard 18T. This is an inexpensive upgrade and can easily be reconfigured back to original specs if not satisfied 3. A 54T chainring would only shift the existing range higher (yes, making hill climbing more difficult). A dual chainring (54T/33T) could be a good alternative.
I’m surprised by the difference in overlapping between the 2-speed and the new 4-speed cassette. Don’t you think the new 4-speed could be easily and conveniently spread out so that it’s both faster and easier on hills? If not, why do you think they made it so “narrow”?
Rear frame clearance doesn’t seem to be the issue here. Maybe the newly designed gear tensioner/cage plat cannot accommodate more than at 18T/12T range? If that is the case, not much we can do (with the exception of using a dual chainring)
I wish I could try, will need a bike to take me to and from work over the 59th street bridge. I'm 57. Would prefer the P line but not sure the 4 gears would work out for me...
Things to consider when choosing between 4 and 6 speeds. 1- The P-Line’s light weight advantage will be noticeable mainly when you are NOT cycling (i.e., when carrying it folded). If you are not planning to do frequent multi-modal commutes, the compromise between weight vs gearing may not be that advantageous. 2- Short of being able to test drive a P-Line, borrow any road bicycle of similar weight (22lbs) and set its gear to be similar to the P-Line’s 1st gear (46 gear-inch). On a 10-speed bike, this will likely be the 4th or 5th gear. Ride the Queensboro Bridge and evaluate how easy (or difficult) it is. It’s likely to be the same with a P-Line. 3- While the Queensboro Bridge 1/4 mile long 58 ft elevation gain (Manhattan side) won’t change, being 57 years old is a temporary situation (that will get worse with time). Keeping a Brompton for 10 years is not unheard of.
I just purchased a P line 12 speed. The 3rd gear on the hub seems so tall it’s only useful on downhills. Is it difficult to reduce the front chain ring size? Are special tools needed?
Installing a smaller chainring (ex.: 44T) is a simple DIY job (you only need a 5mm hex key). You will also need to remove two chain links from your chain (assuming you presently have a 50T chainring). For this, you will need a chain breaker tool as well. Many videos on TH-cam cover the procedure (those from Brilliant Bikes come to mind). Your local bike shop should be able to do the entire job in about 30 minutes.
[5:35] Does the image of 6 speed with two rows (1-3-5) and (2-4-6) correspond to derailleur settings of minus and plus respectively? If it does, I have to say I am a little disappointed that would mean that to use all 6 gears, would you have to shift thusly: -1,+1,-2,+2,-3,+3 ? That seems very counterintuitive, because then you would have between +1 and -2 to use both shifters. I guess as an end user I wish I could use all 6 gears with a minimum of control input, but - alas, it is what it is. In my very preliminary experience, this has got me choosing + in the derailleur, and then just living with its three gears (2-4-6), which for the terrain of Manhattan (whose slopes are usually long and modest) seems to be an effective range.
You are correct, the sequence is 1: 1- 2: 1+ 3: 2- 4: 2+ 5: 3- 6: 3+ And yes, you need to use both shifters in some cases. Note that 2-/2+ are you most efficient gears (2- being the best), so you may want to favor them as much as possible.
@@2Bikes4Adventure Thank you, and I see from the way you write it that the primary shifter is the 3 speed internal gear, not the 2 speed derailleur. As such I guess I could see if I could live in 2-/2+ most of the time, and step down to 1* and up to 3* as situations require. Very helpful. Thanks.
As discussed in our Upgrade Gearing video [ th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html ], installing a dual chainring is a lightweight, simple and cost effective way to significantly extend your Brompton gear range. A similar solution (with in Shimano Ultegra 52T/36T crankset on a P-Line) was used on a 83 hours/1200 miles (1900km) endurance ride [ th-cam.com/video/iMgi0UXJ9Z8/w-d-xo.html ]. So, yes, dual chainring is the way to go.
What is your opinion on having one of those dual chainring (an extra small ring for climbing) for the 6-speed C line? I've read and seen some setups where there's no derailleur but they just use their hand/foot to swap rings.
Installation of a double chainring is indeed a cost effective solution to significantly extend a Brompton gear range. Low cost, high reward. (Ref Upgrading your Brompton Gears th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html )
@@2Bikes4Adventure Just watched the video. Even saw the exact same video in it that gave me that idea, the one with the blue bike that shows the rider kicking the chain into the smaller ring. Thanks for the reference, will keep this video in mind when I do decide to do some gearing upgrades.
@2Bikes4Adventure If I change the p line rear to 11-13-17-21 what would the gear range % be with either the 50 or 44 chainring? I’m thinking of improving it for climbing but not losing too much top end speed. Thanks.
@wanderingsofalanandcaz Replacing the 15 and 18 sprockets with (larger) 17 and 21 will increase your range from 164% to 191% (irrespective of the chainring used). If you do not want to loose existing top speed, keep your 50T chainring. Note that you may have to get a longer chain to accommodate the new 21T sprocket.
Indeed. Reducing your chainring will give you better hill climbing capabilities but at the price of top speed. Your chainring selection should also take into consideration the cadence/speed you are most comfortable with. The wider gap between the gears will reduce your options when trying to maintain your preferred cadence on flat terrain. We would suggest you select it so the 3rd gear represents your most comfortable/default gear while “cruising”.
Do you have any advice in terms of gearing for riding through beach sand? Maybe wet sand. I know ocean spray isn't good for things like steel bikes, but it would be useful to me for certain activities where riding on the beach is necessary. I have thought about fat tires for this purpose but haven't tried yet.
It is less about gearing and more about tire width and pressure. Anything below 2” (50mm) will be way too narrow (needless to say, the Brompton doesn’t meet this requirement). The lower the pressure the better (while still being within manufacturer’s limitations). A fat bike should have no problem. A lower gear in the 30 to mid 30 gear-inches (2.5 - 2.8 meter of dev) so should be sufficient.
The C-Line Explore and Utility come standard with a 50T chainring. The C-Line Urban comes with a 54T chainring The A-Line comes with a 44T chainring. You can request the chainring to be changed at initial purchase time (usually at minimal or no cost) or upgrade it at a later date for a small fee.
Hi , it’s really a great video i watched it nearly 10 times its really useful, but i hsve s question , how to know the meter of development of an internal hub lets say, because the gear ratio alone in percentage doesn’t give us a view if the hub offers less than 2 meter of development in order to be good for climbing . Let say im thinking to put a sturmy archer 5 or 7 speed on brompton how i know if its meter of development is less than 2 ?! In website they just talk about the gear ratio !
The internal hub acts as a “multiplier” when computing a bicycle gear development. For example, a “fixie” with 50T Chainring, 12T Sprocket and 16” wheel would have about 5.52 meters of development (MoD). If we retrofit a RX-RF5 speed Sturmey Acher on such bike (1st = 64%, 2nd = 80%, 3=100%, 4=125%, 5=156% ), we would get: 1st = 5.52 x .64 = 3.53MoD 2nd = 5.52 x .8 = 4.42 MoD 3rd = 5.52 x 1.0 = 5.52 MoD 4th = 5.52 x 1.25 = 6.9 MoD 5th = 5.52 x 1.56 = 8.61 MoD So, the hub alone is not sufficient to compute gear development, we need to factor in the chainring and sprocket it will be connected to.
@@2Bikes4Adventure that makes sense,so if we put a 44 chainring with that same internet hub we would get a less MoD on the first gear to fit the hill climbing Thanks alot ♥️
Nice video. Current T line -stock 50 T chain ring can only be upgraded to a 56 T chain ring via Brompton i.e excluding 3rd party chain rings. I’ve notice I tend to spin out easily on the stock 50 T so upgrading to 56 T.
The P-Line chainring is a regular 130BCD, so it can easily be changed for a 44T, but this will likely be the responsibility of your local bike shop (or you), as Brompton seems to focus on the 50T standard configuration.
![เปิดบ้าน พี่ตูน Bodyslam หลังใหม่คนแรก ที่ภูเก็ต l [Nickynachat]](http://i.ytimg.com/vi/flFwcmyDQSk/mqdefault.jpg)
I came for something about Brompton gears. I found one of the best videos on TH-cam with graphics explaining gear ratios. Great job!
Its spring in Quebec and my favourite bicycle engineering professors are back at work!
Class dismissed, go out and cycle!
@@2Bikes4Adventure Yes, ma'am.
I've just binge watched some of your technical videos regarding Bromptons, and I must say I'm baffled by the quality of your explanation as much as your production value, which very much go hand in hand.
Thank you for putting out quality content, it goes a long way
Stay tuned for more technical videos in the future
@@2Bikes4Adventure ill be here for it !
You have a talent for storytelling. Excellent presentation of technical data.
hello, we, 2 of us who are considering foldings bikes, brompton, for activity similar to your channel, although for us, just starting, watched this video, and then several more.
I KNEW Brompton offered multiple gear options, and methods. I KNEW could change the overall standard gear ratio by change a major gear. I KNEW about overall idea of gears being useful for hills, vs flat, of range of gears, of steps, ratio, between gears.
YET, I DID NOT UNDERSTAND on any deep level, any of this. Just sort of that existed. Your VIDEO made all of this so clear, on not just Brompton, yet across ALL bikes. I have a bike, I know how to shift, I feel the impact of various gears, yet never really understood at level that I now do. All in under 9 minutes. Stunned.
Upvoted, and subscribed!
Stay tuned for more videos.
The insistence on frenching up every remotely french looking word, especially a word like "Sport", is slaying me rn 😂
Riding a bike and understanding it in detail was really a new concept.
If the second hand market here were popular or less unregulated, I would probably consider seriously too. It's excellent for storage and portability.
This has been EXTREMELY helpful - a huge thank you for this well-told brompton gear summary!
BTW, we discussed the new 12speed in this video:
th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
I was hungry for data, and now I'm full. Thanks for giving me exactly what I was craving!
That is food for thought!
This is really well done and super informative. Thank you for sharing your insight and explaining so clearly.
I think this is extremely helpful! Your thoughtful visuals, explanatory script and advice are simply a level above what I've seen elsewhere. Thank you so much!
The next version of this video will include the 12-speed that was released in Jan 2024. Meanwhile, this video on the subject provides the main details: th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
As an owner of the former Top, SuperlightM6LXBrompton, I have used it during vacations on our only Danish, Rocky Island of Bornholm, and it has a serpentine road going up to a former lighthouse. As an elderly, too heavy man in a bad shape I had to walk once in a while, going up and also to pass the several "cattle prevention bars", crossing the road at intervals, some with a self closing gate to the side. My 6 gears came in fine but wasn't even enough for the job! I do also own a 33 gears carbon MTB, with gears which are so low that I can't even start on a flat road in them, but going up an extreme hill in a wood, they are fine!! Finn. Denmark
Everything I’m learning about Bromptons is from your videos! Thank you!
@tinylil, stay tuned for more videos 😊
What a fabulously informative and well-explained video! I was almost ready to buy a 4-speed P-line Brompton for touring, but now think the 6-speed C-line will probably be better.
Some 3rd party upgrades (ex.: dual front ring ) would be required to make the P-Line a good touring bike.
have you taken it out on any tours yet? I'd love to hear how you got on
The clarity of presentation is just awesome. Great video!
Another really interesting, helpful and educational video about Brompton cycles and related issues. Many thanks.
I finally understand the different gearing configurations with this video. Thank you!
Such an awesome video. I’m speechless, really. The simplicity belies much planning and effort, I suspect. Thanks Pam.
Accurately researched and superbly presented - thank you!
Thanks for the gear ratios, it's very useful for making a buying decision and I couldn't find it on the Brompton site
great video never have seen gear inch explained so well and elevations thanks for the video
Awesome video & nice information , the only reason i'm getting brompton because of wide ratio 🔥🔥
Probably the best presentation I've seen on all current Brompton gear ratios (including the new T line which was what I was looking for). Better than my spreadsheet and coming to the same conclusions on choice - i.e. 6 speed classic with standard/reduced chainring is best for touring/hilly terrain. I would however like more gears to reduce the jumps and to remove the compromise of having to either pedal furiously or with a slower less efficient cadence in order to maintain a particular speed, something which the new 4 speed doesn't address.
Adding a 3rd sprocket or upgrading to a dual-chainring could be solutions to improve range and gear gap (ref. our video th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html )
Thank you so much for this informative video! Very helpful indeed! I will definitely go for the C-Line and choose my favourite Cloud Blue Brompton! M6L 😊❤
there is so much value in these videos it's ridiculous
@mattong8130, stay tuned for more.
Thank you again. Really appreciate the effort you put in to help us understand.
Thank you so much for this explanation. I feel I can make a much more informed purchase.
Extremely well presented summary. Thanks!
Excellent video! Love the comparison at the end. Thx!
Thanks for this really helpful summary. You've enabled me to make my choice!
Since this video was published, Brompton announced the release of 12speed versions for the C Electric, P Electric, P-Line and T-Line. Here's our video on the subject: th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
That’s an excellent and informative video. Thank you for making it.
Pam and Gilbert
Love the video. Fantastic comparison and very easy to see the difference on gearing.
I had the opportunity to ride the new T line, it does lack gears for our touring purposes, but love the quick and staight response to pedal.
Once more congrats, love it!
Hi Chris, we did see your NYC video(s) concerning the T-Line.
What a great experience it must have been riding it.
Brompton did sacrifice gear range when they decided to go for a such a lightweight solution. Great for a quick commuter but limited as far as touring goes.
@@2Bikes4Adventure Yes, it is an amazing bike, but not for us that like to use it on biketouring going uphill and full of bags.
I love these videos that scientifically explain the reason for things. You guys are great!
I won't be able to participate to the TB5BNY this year, hope to meet you next year 👍🏻😊🚵♀️
Very clear explanation. Excellent.
Well researched with great delivery. Thanks.
Perfect to choose the best Brompton !
Thanks😄
Hope you get yours soon (or maybe you have one already??)
Ive got a p line and I love it! just wish I had a wider range of gears so I could keep up with my road bike friends if I wanted.
The 4 speed range is indeed narrow. A possible solution could be to add Schlumpf drive.
How is it on the hills? What size chainring have you got? What sort of gradients is it capable of climbing in the biggest ring at back?
@wanderingsofalanandcaz We do have a 44T chainring on our M6R.
As for the gradient it can tackle, it will depends on fitness level. We would refer you to the graph at 06:43 for a rough estimate: About 90 min on a 7% grade, 45 min on a 10% grade and 1 min at 20%.
Excellent video; thanks for taking the trouble to make it.
Great info! In Singapore and some Asian countries we have many different brands of ‘Brompton clone’ so call trifold bikes that comes with default 46 or 48T chainring running on the SFR3 internal hub and 2 or 3 external sprockets, giving a 6 or 9speed configurations.
@DCPedal, what are the more common sprockets size found on those trifold bikes?
@@2Bikes4Adventure 13,15,17
Love your channel 👍🏻
Hello Pam and Gilbert, so interesting like always!! I must definitively change with low gear for my next travel. Thank for your video precision!!
Going for a 44T chainring is an inexpensive (DIY) upgrade that you will bless every time you go uphill. Don’t go up without it :-)
@@2Bikes4Adventure yes definitively!!
Neat and well-explained. I recently upgraded my three speed to a 5xspeed just so that I would get a little bit more on the lower and higher end of the gear range. 256% as a whole lot better than the previous. But I can certainly see where others with the three speed have gone to the 44 tooth to get some of the same low-end gains.
Sturmey Archer S-RF5(W)? Easy to implement?
@@2Bikes4Adventure mine was the result of getting a custom wheel made by BrommiePlus. It doesn’t look like it was all that complicated though. I wanted the 8spd SA, but that’s no where to be found anymore.
I’m running the 50t up front and 13t on the rear, gear inches (according to their chart) are 40/48/64/85/102 for 256%, which is definitely in the “comfy” range according to your video
This video was amazing, thank you for sharing!
Hi, wonderful and instructive videos. Could you please reveal how you make them? Or at least some essential hints for the animations? Keep on, I’m delighted!
GarageBand for the audio. Keynote feature set is relatively limited, but the price is right (free).
This video is Science. You have been Korea! I Love you. I am Korean 😊
다음에는 제주도로 가보겠습니다!
@@2Bikes4Adventure 여름만 피하세요! 너무 덥고 습도가 높습니다 :)
Thanks so much!!
My advise for gear selection:
1. Do you climb hills, strong head winds and are you not as strong? Buy the 6 gear system.
2. Do you ride in the city, less then 5 km/ 3 miles? The 4 gear system will do if you are not so strong. The 2 or 1 gear if you are strong. The 3 gear is not useful, the gears are spaced too far apart. So the gear 3 you will seldom use. Unless you change the sprocket to a bigger sprocket or a smaller chain ring, so you can use gear 3 as well.
3. Do you use your Brompton for touring with luggage. Buy the 6 gear.
44T is the default for the A Line
@@PPJ9274 That's what we heard as well. We did install 44T on our M6R at purchase time.
I wish Brompton did a 39T chainring as I never use the 3 High gear. I had the thirdparty 39T but it did not fit the Shimano crank I installed to my M6 so I reverted to the 44T.
Thank you for this video! I have folding bike with 7 speed 👍🍀
Massively informative as usual.. Really going to have to look replacing the internal hub on my 3 speed as the weight to gearing ratio is the worst out of all of them. Unsure if I go for a aftermarket derailleur solution or go for a 6 speed hub. Really its naughty that brompton make two different internal hubs that weigh roughly the same but then force you to buy the BWR to get the two sprockets rather than just putting it on both models which gives you the chance to upgrade. Guess they need some incentive for people to go to the 6 speed as a default..
The dual-drive 6 speed (using the BWR) was a stopgap solution following the demise of the Sturmey-Archer 5 speed hub. Unfortunately, no better solution has been put forward.
@Wildefyr I can recommend the 5spd hub. Recently went from the 3spd to 5spd and having the extra lower and higher have been quite nice. I feel the 3spd w/50t is really not all that bad. But I did need the occasional speedy or “nah, can I get lower” kind of gearing w/o changing the middle. This has been great, despite the weight. Got it at BrommiePlus.
I put a 42 tooth Campy GS crankset on my 6 speed. Schweet!
A nice explanation, particularly of the effect of varying power output on hill climbing - very good to relate this to gear choice as well. One question - am interested in your foot position on the pedals. We are normally taught to use the forefoot (or at least I was!), but you are using your mid foot on the pedal. It would be helpful to know why - perhaps I am doing it wrong?
While it is usually accepted that positioning the ball of the foot over the pedal pivot is optimum, some research has found that it may not be critical (www.researchgate.net/publication/6886747_Is_economy_of_competitive_cyclists_affected_by_the_anterior-posterior_foot_position_on_the_pedal).
Our approach is less scientific and more aimed towards “do whatever feel right”. So, as the day progresses, we are likely to move our feet position slightly depending on the level of effort required (and fatigue level). It may not be always the most optimum configuration, but than again, we are not in it for the performance aspect.
@@2Bikes4Adventure Thanks, this is useful. Always interesting to have an alternative to the established wisdom.
Fab video thank you! Perhaps a further consideration if cycling in muddy or off-road conditions is that a hub gear system is less likely to get ‘stuck’ than derailleur, particularly when it’s so very close to the ground?
Indeed, the 3speed A and C lines are less prone to gearing contamination than the derailleur based models (2-4 and 6 speed).
This is great - thank you! Would you consider updating it to incorporate the newer 12 speed gearing option?
12 Speed discussed in this video: The new 12 speed Bromptons
th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
Excellent video. When I was riding my Brompton M6R with 50T on the hill with 10%, I know it’s time to get a 44T. Just wonder what will the curve be at 6:31 when using 50T, how long does it takes for people to be exhausted with a 50T🤔🤔? And I guess also having a 55/34 traditional crankset for T-line probably will be an excellent option to turn it to an amazing bike with wider range, lightweight and performance.
Thank you for your wonderful video again!
The graph at 6:31 is for the default chainring configuration (50T for 1, 3, 4 and 6 speed, 54T for 2 speed). At 6:41, we changed to 44T for the 6 speed only. A dual chainring (54/34) would indeed be a inexpensive way to improve the gearing range.
@@2Bikes4Adventure Thank you! I understand now :)
Awesome, I wanted to look up your previous gearing video as my brompton tour in the hills did not go as planned and I was curious if I should go with 44t or maybe check for even smaller 3rd party options. Thanks for that perfect timing!
A 39T would be a simple upgrade to do.
If there is some interest, we may create a small video on 3rd party gearing options.
I ordered myself a 40t H&H Chainring. Will let you know how it goes. I was tempted to even get myself the three sprocket external upgrade, but one thing at a time :)
Upgrading the chainring will be less work than going with a 3rd sprocket configuration. Keep up posted with the results
@@2Bikes4Adventure Thanks! Exactly my thought - since the part is for the Brompton I hope the H&H one fit nicely onto the spider cranks and I hope on the long end it will do around 30kph with my normal cadence (ritzelrechner at least said so)
Anyways thanks for offering to look into 3rd party gearing options. There is crazy stuff out there (schlumpf, rohloff, front foot derailleurs) but all fairly low volume with limited information. For me this is a bit too custom as I want my brompton to be reliable
Awesome video. I like that you actually share how a gearing ratio could affect a climb. I wonder if one could do aftermarket modification from 44T chainring to a smaller 36T or 34T for better climbing experience? Many thanks.
38T or 39 T are probably the smallest 130BCD chainrings you can get. You could go smaller with a dual chainring however.
This was really educational on gear inches and leverage. It's been helpful from your other videos combined.
I checked the single speed line was 50T on its formal website. For the last part on a 4.5% slope (equal to 22:1), how hard could that be for an average-fit person close to 60? Thanks.
According to the graph at 6:21, a 70Kg (young) adult cycling a single speed T-Line at 60rpm on a 4.5% slope would need a break after approximately 15 minutes.
Assuming the same body mass, expect about 10% drop in performance for every decade above 30 years old. So, a 60 years old cyclist would likely stop after 10 minutes or so on the same slope.
@2Bikes4Adventure Really appreciate for your time replying, Thanks a lot.
Thank you - very useful!
One update I notice on the Brompton support website, they show the 4-speed has a 56T option now which brings the top gear on the 6 speed closer to the normal 3-speed: 6.74m in the top gear.
Thanks for the heads-up. We can see why somebody buying a T or P-line would want a bigger chainring!
I have got a 6speed 44T equipped, but the two highest speeds are anyway too strong to push.... I hope Brompton would realize a 39T-40T in the future.....
I agree, even downhill 3+ or sometimes 3- feels just too fast for this little bike. For me at least, if someone likes to go with 54t for land speed records, thats cool too
A 39T would be a simple upgrade to do.
If there is some interest, we may create a small video on 3rd party gearing options.
@@2Bikes4Adventure the upgrade you told is possibile only with the old Brompton crankset, which had a standard 130 mm BCD, and, for example, you can fit whatever Shimano chainring 39T; models after 2017 though, have got a new personalized (very odd 😏) crankset with 124mm BCD, so you are obliged to use only Brompton components, and the smallest chainring made by Brompton is 44T... I'd had to buy on line a second hand pre-2017 crankset is England... (I'm Italian)🇮🇹😄
Going to need a 12x video soon!
Indeed. For now, we have this one: The new 12 speed Bromptons
th-cam.com/video/1hWXTlpZrRs/w-d-xo.html
for P line , will there be any difference changing the cog from 11-13-15-18sprocket 50T changing to 11-13-17-21 sprocket 54T chainring?
Interesting upgrade. The total gear range would increase from 164% to 191% , providing a lower first gear and faster 4th gear. There would be a very noticeable gap between the 2nd and 3rd gear however. You may want to confirm your favorite cadence would not be affected by this gap.
@@2Bikes4AdventureIf I change the p line rear to 11-13-17-21 what would the gear range % be with either the 50 or 44 chainring? I’m thinking of improving it for climbing but not losing too much top end speed. Thanks.
I checked T line on Brompton's website, and the only 2 models available have gears…
I'm looking for a model to carry on the bus daily,
A line 3 gears seem interesting, despite the Dahon Marine D8 looking more attractive…
If you plan to carry your folded bike in a bus on a daily basis, we would recommend a Brompton
amazing!!!
Thank you for your wonderful illustration! May I seek your advice: currently running a 54T 3speed SA for fitness riding (20-45km, x 2 per week, average 22km/hr over 1-2hrs) at relatively even terrain (parks & road) I am keen to get the P line to improve my performance (to cycle further & longer & perhaps fill the gap of a missing gear (betw 2nd & 3rd) when fatigue sets in. However, after watching your video & realise the 177% vs 164% gearing range, I am a tad hesitant about the earlier intention. Would love to hear your opinion with your vast experience! Thank you ;)
@eugenetmy, the excitement of owning a brand new bike is not to be ignored, but in this particular case, the price of the 4th gear will be significant.
If budget is not an issue, I would go for it (and probably consider a 3rd party 130BCD 56T chainring to shift the gear range upward).
Once you have your new P-Line, you could always sell the old 3 speed to help finance the new acquisition although there is nothing wrong with owning more than 1 folding bike (we own 10).
On the other hand, if cost is an issue, a cheaper option would be to upgrade your 3 speed to a 5 speed hub. The gap between the 4th and 5th gear will be 18%, the same as the gap between the 3rd and 4th on the P-Line. Furthermore, the total range is 225% (vs 164%). True, the bike will be heavier than the P-Line, but this upgrade would probably cost 1/10 the price of purchasing the new bike.
Enjoy your Brompton (whichever model or setup you choose).
I got a C Line Urban for my commute to work. My commute is less than 3km, and there's only one hill of any significance; it's less than 250m, and depending on the stoplight at the beginning, I can generate enough momentum to fairly easily handle the first 1/3 of the hill. So for me, the C Line Urban was the perfect solution.
That being said, I come from a road cycling background, and am used to covering distances on the road much faster; I tend to turn taller gears with relatively lower cadence. Do you think upgrading to a 56t chainring (I believe my bike came with a 54t ring) would make a noticeable difference?
Upgrading the chainring from 54T to 56T and 16T to 17T would both make you marginally faster (1km/h at 70rpm in 2nd gear) and provide better hill climbing performance in 1st. It’s a low cost DIY upgrade that can be easily reversed if you don’t like the end result.
@@2Bikes4Adventure great. Thank you for the recommendation.
Hi, I have recently discovered your videos and I was impressed by the knowledge and the way you explain things. I've just bought a Brompton P Line (because my first priority is the weight and couldn't find the t line anywhere) and I find that the gear range is too narrow for me. I often find myself frustrated when I can't take advantage of a downhill to reach full speed. I was thinking of the following options:
1. (ideal) Increase the number of sprockets (e.g. 5 or 6 total sprockets) to increase the range. I guess I would have to choose sprocket sizes that make sense, in order to cover the whole desired range (preferably similar to the 6 speed brompton). You think it would be possible? Would it require to make any modifications to the rear triangle (e.g. widen it) ? what would be the most lightweight way to do it?
2. (good) Keeping the number of sprockets the same (i.e. 4) but choose different sizes so as to increase the range. Would that be possible? and what kind of range do you think I could reach, keeping a satisfactory overlap between the four gears (as per your video) ? What would be the most lightweight option here?
3. (least preferable) If not possible to change the range without adding considerable weight or irreversibly altering the frame, perhaps I should shift its current range upwards? Would getting a 54T chainring mean that I could go faster downhill but would have to put more effort while climbing uphill?
Thanks in advance!
Increasing the gear range on the standard 4 speed P and T-Line will likely be a hot subject in the coming months
1. 3rd parties started offering upgrade kits like this one: www.fantastic4toys.com/collections/brompton-upgrade-parts/products/thx4ride-7-speed-kit-set-for-brompton-bicycle-p-line
2. Some P-Line owners report having no problem replacing the first gear with a sprocket bigger than the standard 18T. This is an inexpensive upgrade and can easily be reconfigured back to original specs if not satisfied
3. A 54T chainring would only shift the existing range higher (yes, making hill climbing more difficult). A dual chainring (54T/33T) could be a good alternative.
@@2Bikes4Adventure thanks!
I’m surprised by the difference in overlapping between the 2-speed and the new 4-speed cassette. Don’t you think the new 4-speed could be easily and conveniently spread out so that it’s both faster and easier on hills? If not, why do you think they made it so “narrow”?
Rear frame clearance doesn’t seem to be the issue here. Maybe the newly designed gear tensioner/cage plat cannot accommodate more than at 18T/12T range? If that is the case, not much we can do (with the exception of using a dual chainring)
I wish I could try, will need a bike to take me to and from work over the 59th street bridge. I'm 57. Would prefer the P line but not sure the 4 gears would work out for me...
Things to consider when choosing between 4 and 6 speeds.
1- The P-Line’s light weight advantage will be noticeable mainly when you are NOT cycling (i.e., when carrying it folded). If you are not planning to do frequent multi-modal commutes, the compromise between weight vs gearing may not be that advantageous.
2- Short of being able to test drive a P-Line, borrow any road bicycle of similar weight (22lbs) and set its gear to be similar to the P-Line’s 1st gear (46 gear-inch). On a 10-speed bike, this will likely be the 4th or 5th gear. Ride the Queensboro Bridge and evaluate how easy (or difficult) it is. It’s likely to be the same with a P-Line.
3- While the Queensboro Bridge 1/4 mile long 58 ft elevation gain (Manhattan side) won’t change, being 57 years old is a temporary situation (that will get worse with time). Keeping a Brompton for 10 years is not unheard of.
I just purchased a P line 12 speed. The 3rd gear on the hub seems so tall it’s only useful on downhills. Is it difficult to reduce the front chain ring size? Are special tools needed?
Installing a smaller chainring (ex.: 44T) is a simple DIY job (you only need a 5mm hex key). You will also need to remove two chain links from your chain (assuming you presently have a 50T chainring). For this, you will need a chain breaker tool as well. Many videos on TH-cam cover the procedure (those from Brilliant Bikes come to mind). Your local bike shop should be able to do the entire job in about 30 minutes.
[5:35] Does the image of 6 speed with two rows (1-3-5) and (2-4-6) correspond to derailleur settings of minus and plus respectively? If it does, I have to say I am a little disappointed that would mean that to use all 6 gears, would you have to shift thusly: -1,+1,-2,+2,-3,+3 ? That seems very counterintuitive, because then you would have between +1 and -2 to use both shifters. I guess as an end user I wish I could use all 6 gears with a minimum of control input, but - alas, it is what it is. In my very preliminary experience, this has got me choosing + in the derailleur, and then just living with its three gears (2-4-6), which for the terrain of Manhattan (whose slopes are usually long and modest) seems to be an effective range.
You are correct, the sequence is
1: 1-
2: 1+
3: 2-
4: 2+
5: 3-
6: 3+
And yes, you need to use both shifters in some cases. Note that 2-/2+ are you most efficient gears (2- being the best), so you may want to favor them as much as possible.
@@2Bikes4Adventure Thank you, and I see from the way you write it that the primary shifter is the 3 speed internal gear, not the 2 speed derailleur. As such I guess I could see if I could live in 2-/2+ most of the time, and step down to 1* and up to 3* as situations require. Very helpful. Thanks.
Wonderfull!!
Was this at the Brompton Junction in NYC?
Yes, it is. Filmed in January 2019
Hi. Would you consider using a aftermarket 53T/33T chainring to give more gear ratios? I can’t wait to have one. It helps with touring and climbing.
As discussed in our Upgrade Gearing video [ th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html ], installing a dual chainring is a lightweight, simple and cost effective way to significantly extend your Brompton gear range.
A similar solution (with in Shimano Ultegra 52T/36T crankset on a P-Line) was used on a 83 hours/1200 miles (1900km) endurance ride [ th-cam.com/video/iMgi0UXJ9Z8/w-d-xo.html ]. So, yes, dual chainring is the way to go.
What is your opinion on having one of those dual chainring (an extra small ring for climbing) for the 6-speed C line? I've read and seen some setups where there's no derailleur but they just use their hand/foot to swap rings.
Installation of a double chainring is indeed a cost effective solution to significantly extend a Brompton gear range. Low cost, high reward.
(Ref Upgrading your Brompton Gears th-cam.com/video/-Q9wd8Ewlec/w-d-xo.html )
@@2Bikes4Adventure Just watched the video. Even saw the exact same video in it that gave me that idea, the one with the blue bike that shows the rider kicking the chain into the smaller ring. Thanks for the reference, will keep this video in mind when I do decide to do some gearing upgrades.
@2Bikes4Adventure If I change the p line rear to 11-13-17-21 what would the gear range % be with either the 50 or 44 chainring? I’m thinking of improving it for climbing but not losing too much top end speed. Thanks.
@wanderingsofalanandcaz Replacing the 15 and 18 sprockets with (larger) 17 and 21 will increase your range from 164% to 191% (irrespective of the chainring used).
If you do not want to loose existing top speed, keep your 50T chainring. Note that you may have to get a longer chain to accommodate the new 21T sprocket.
@@2Bikes4Adventure Excellent thank you. Obviously a 44 or 46 chainring would help on the uphill though yes?
Indeed. Reducing your chainring will give you better hill climbing capabilities but at the price of top speed.
Your chainring selection should also take into consideration the cadence/speed you are most comfortable with. The wider gap between the gears will reduce your options when trying to maintain your preferred cadence on flat terrain. We would suggest you select it so the 3rd gear represents your most comfortable/default gear while “cruising”.
Do you have any advice in terms of gearing for riding through beach sand? Maybe wet sand. I know ocean spray isn't good for things like steel bikes, but it would be useful to me for certain activities where riding on the beach is necessary. I have thought about fat tires for this purpose but haven't tried yet.
It is less about gearing and more about tire width and pressure. Anything below 2” (50mm) will be way too narrow (needless to say, the Brompton doesn’t meet this requirement). The lower the pressure the better (while still being within manufacturer’s limitations). A fat bike should have no problem. A lower gear in the 30 to mid 30 gear-inches (2.5 - 2.8 meter of dev) so should be sufficient.
@@2Bikes4Adventure omigosh thank you. I read it in the voice. Now I know what to get.
😍
how do I know whcih C bike is 40T or 55T?
edit: I couldnt find the info on bromptons website and I nerd the lower gear for the hills in my city
The C-Line Explore and Utility come standard with a 50T chainring.
The C-Line Urban comes with a 54T chainring
The A-Line comes with a 44T chainring.
You can request the chainring to be changed at initial purchase time (usually at minimal or no cost) or upgrade it at a later date for a small fee.
Hi , it’s really a great video i watched it nearly 10 times its really useful, but i hsve s question , how to know the meter of development of an internal hub lets say, because the gear ratio alone in percentage doesn’t give us a view if the hub offers less than 2 meter of development in order to be good for climbing .
Let say im thinking to put a sturmy archer 5 or 7 speed on brompton how i know if its meter of development is less than 2 ?!
In website they just talk about the gear ratio !
The internal hub acts as a “multiplier” when computing a bicycle gear development.
For example, a “fixie” with 50T Chainring, 12T Sprocket and 16” wheel would have about 5.52 meters of development (MoD).
If we retrofit a RX-RF5 speed Sturmey Acher on such bike (1st = 64%, 2nd = 80%, 3=100%, 4=125%, 5=156% ), we would get:
1st = 5.52 x .64 = 3.53MoD
2nd = 5.52 x .8 = 4.42 MoD
3rd = 5.52 x 1.0 = 5.52 MoD
4th = 5.52 x 1.25 = 6.9 MoD
5th = 5.52 x 1.56 = 8.61 MoD
So, the hub alone is not sufficient to compute gear development, we need to factor in the chainring and sprocket it will be connected to.
@@2Bikes4Adventure that makes sense,so if we put a 44 chainring with that same internet hub we would get a less MoD on the first gear to fit the hill climbing
Thanks alot ♥️
Nice video. Current T line -stock 50 T chain ring can only be upgraded to a 56 T chain ring via Brompton i.e excluding 3rd party chain rings.
I’ve notice I tend to spin out easily on the stock 50 T so upgrading to 56 T.
Give us some news once you have the 56T
Can you put a 44T on the p line?
The P-Line chainring is a regular 130BCD, so it can easily be changed for a 44T, but this will likely be the responsibility of your local bike shop (or you), as Brompton seems to focus on the 50T standard configuration.
6:06
The P line’s gearing is disappointing.
Makes no sense to me who knows nothing about bike gears.