Best mod you can make on a 6spd Brompton. They are massively over geared in std spec with 50T and even 44T front chain ring. If you wish to go smaller than 39T then you have to fit a smaller crank spider, but then you would really lose top end gears. With a 39T top gear spins out at about 25-26mph probably with a cadence of about 120-130. Most people can't pedal cadences this high. Having a 39T makes general riding and indeed touring so much more enjoyable as you can use all the gears. Brompton should really produce their own 39T front chain ring.
I agree. I bought the bike with a 50t chainring, swapped for a 44t one and still wasn't using all the gears. I'm much happier with the 39t solution. I don't mind coasting downhill, with climbing being the priority for me. I've had this on for about 2 weeks now and I'm not switching back.
@@ultrastoat3298 I believe so. Maybe fitting their 44T or 42T front chain ring is the reduction? Don't know. In any case it wasn't enough for me when loaded up to go touring climbing serious hills/mountains.
I did this to my Brompton and it transformed it. It came with a 50t so i thought swapping to a factory 44t might sort matters. Nope. Wish I'd gone straight to a 39t. I have no idea why Bromptons are so over geared. Even with a 39t, top gear is a little high for the flat. Did a test ride in the Cotswolds on Friday with my 39t and it was spot on. No more getting off to push!
I did exactly the same as you. Swapped for 44 first and then went down to 39t. I just came back from tour and the chainring choice was a game-changer for hill climbing.
I've done the same. Very well explained. Best decision ever. I've ridden Alpine mountain passes with a 39 T front chainring and I've bike toured with it (tent, mountain pasdes and all). Yes, on the downhills I spin out but that doesn't matter because climbing that's the hard part. Easy climbing with a low gear that's actually low is what it's all about. A lower low gear is much more "knee friendly" too ;)
Thank you for sharing your experience with a similar setup. I ended up touring with the bike and it was a much improved experience. While the route was mostly flat, the few steep hills I encountered were very doable with this setup and a loaded Brompton. So, like you, I'm happy with this.
Excellent video! I put a 39-tooth chainring on my new Brrompton, replacing a 50-tooth (groan!) ring. Works great! I wish I had this video to watch, though, before I made the swap, as it would have been helpful and answered a number of questions. Well done!
Very well explained video. Recently bought a Brompton and like you finding it very over geared. Will be making the same change very soon to allow for a more versatile ride. Thanks for taking the time to film. Hope your enjoying your Brompton as much as I do great fun. All the best Pete 👍🚲
In my opinion, if this is necessary is because the gearing of a brompton is not adequate, even in a 6 speed. In my 26 bike i have a 38T (11-42). Requiring a 39T with such a small wheel could only mean that the gear range is narrow and too long.
wow touring with Brompton, I was wondering how that's even better than a touring bike especially if you need to take it on a bus/train/plane with you.definitely a good idea for cross country or international touring, can't wait to watch your Brompton videos,Thanks a lot
I think it'll be a great challenge. I have to consider packing lightly, which will be new for me. 😉 Multimodal travel will be much easier with the Brompton for sure.
@@WheelsonaBike indeed! Me too! I just purchased my first Brompton as well. C line explorer. I hope to experience some touring too! I enjoy watching your videos! So nice to see you touring on a Brompton! I’m going to be changing to chainring to 44t. Question, do you loose speed when you drop down to a smaller chainring? Thanks!
@ShadowWilliams1265 I can't really answer your question as speed is the last thing I ever worry about and I just don't pay attention to it. I suspect you would loose speed on flats and downhills and you would potentially spin out.
I did the same thing on my Dahon but added the Tern mainstay to keep the chain on the chainring. Without a front derailleur, a guide of some sort, or a narrow-w8de chainring, the chain can pop off on some terrain or when shifting cassette cogs.
There's a tensioner on the chain, so I hope that will keep it on. I've not had any issues with the chain coming off yet, although someone commented that their wife had experienced it.
Thank you for this video and the very clear instructions! I am about to make the same change on my Brompton and this looks to be the perfect step by step guide 👍
This is my first Brompton video, I have never had the privilege of experiencing a Brompton, although I have seen several E-Brompton commuters going to work at our local hospital and local students and townies running errands in my area of Celebration, Florida. The Brompton certainly appears to be a very efficient bike and fairly simple to work on and to upgrade.. It is my hope that the wild fires have subsided in your area of Canada, thank you for sharing and stay safe…
There are more Bromptons riding around Toronto as well. Not very many eBromptonzs yet, but I suspect this will change. No wildfires in and around Toronto, thankfully, just lots of smoke at times. But very strong weather systems coming through.
Brilliant acquisition, Agnieszka, and it is a Piccadilly Blue C Line! 🤩I bought this same colour Brompton C Line last year and I absolutely revel in riding it around New York City. I have been riding my steed along the Empire State Trail but nothing as adventurous as your undertakings. Thank you for your inspiring content. Take care! Ta!
Hello fellow Piccadilly Blue-er! It's a beautiful bike and a joy to ride. It continues to impress me so much and the fact that it folds so small only adds to the wow factor! One day, I will continue along the Empire State Trail and ride it to New York. Need to finish that trail. 😉
When I bought my 2019 SuperlightM6LXBrompton, I at first wondered for what use I had the - low set of gears, till I met a steep Danish serpentine road, and even had to walk up, for a higher speed! I find my present 6 speed gearing fine for most purposes (I have a selection of other size, front chainwheels also, but I have never changed to any of those!). But if in need, it is possible to buy a - double chainring in front (And a Changer for the frame), giving 12 speeds, with an absurd changing between the possible gears! I also have some extra size, titanium chainwheels for for my 3 speed gear hub, in other sizes than the original 2. My bike at present weighs 8,5 kilo, with mudguards! Finn. Denmark
There are always options, aren't there? I think if you can tinker with the bike, instead of asking a mechanic to do something for you, that's better, as you can try different solutions and make the bike work for you and your riding conditions. Thank you for listing the available options.
Shimano offers a 39t chain guard and separate 39t chain ring. Just ordered them and hope to install this next week thanks to this excellent video, thank you !!
I've been thinking about making the same mod to my 6 speed Brompton. Would love to see more about how you intend to use your Brompton for touring and how you will equip it.
Why didn't you ad the Chain cover again also, if possible (You are able to buy chain rings with an integrated cover)? At least I use pants on my bike. And when first using my 2019 Superlight 6 speed I wondered for what use I had the rather low gears, till I met an absurd hill going up, and had to walk on top! Finn. Denmark 😄
The 39 tooth chainring did not come with a chain guard. I'm not sure any of the 39t chainring do. Someone mentioned a Shimano 39t chainring with a guard in the comments, but then followed up that the guard didn't work with the cranks. I know there's is a 40t chainring that has a guard, so maybe that could be an option for you.
My wife's Brompton has a 39T chainring also. The issue she had while touring was that the chain would occasionally came off the chainring. I believe it was due to the fact that the 39T chainring was meant for a 10 speed chain, so there was quite a bit of side to side play when fitted with the Brompton 8 speed chain. Of course this particular issue went away after I changed the chain to a 10 speed, while adding an extra sprocket gear at the rear.
Thank you for flagging this. Was there a specific scenario when the chain came off? Under torque or just generally riding? Did it start happening right away or do this appear after prolonged use? Also, can you elaborate on adding an extra sprocket gear? What do you mean by that?
@@WheelsonaBike The Chain seldom comes off but it does, and I don't think the chain needs to be under loaded. As for the extra sprocket gear, you may want to google "Brompton 6 speed to 9 speed". Basically, replacing the stock 2 gears at the rear with 3 gears(10/11 speed), then change the chain and shifter accordingly.
One-by chainring can never support all demands the road will bring, unless there is a Rohloff speedhub in the back. The bicycle will be either sutiable for hills and thus relatively slow or suitable for flat and tail wind. For details, see The path less pedaled channel, or calculate gear ratios. The reason Brompton comes with 50t is most likeky due relarively small wheel diameter....20'' ? If you really like this bike, one (pricey) solution could be Schlumpf Drive unit. They are excellent for trikes and bikes with small wheel diameter.
I realize the limitations, and don't expect the Brompton to replace my touring bike. There are many channels that identify the shortcomings of Brompton one by drivetrains, you mention one, another is 2 wheels 4 adventure who have done an amazing job at bringing a lot of knowledge together.
@@WheelsonaBike Thanks again, did the conversion last week and after a few test rides I can say it was a good decision 🤙 I also took the time to replace the bottom bracket, instead of the Brompton I now have a metal one from Shimano
I have a 44t and want to switch to 39t, but somehow the shop in montreal couldn't order one for me, which brand did you use and did you get it in canada?
Thanks for your question. Yes, I bought the chainring from a shop in Toronto. I show the package in the video - it's a SRAM chainring. Here's the exact item I bought www.sweetpetes.com/product/sram-road-inner-chainring-158599-1.htm?variations=617438&catalogTypeId=1
Challenge. Attempting to tour on a 6 speed bike will bring its own set of challenges and I'd like to experience that. Also, I may be taking the train and unfortunately our train system in Canada does not welcome full size bikes on board. They used to, now they're waiting for updated cabins ... So they say...
Best mod you can make on a 6spd Brompton. They are massively over geared in std spec with 50T and even 44T front chain ring. If you wish to go smaller than 39T then you have to fit a smaller crank spider, but then you would really lose top end gears. With a 39T top gear spins out at about 25-26mph probably with a cadence of about 120-130. Most people can't pedal cadences this high. Having a 39T makes general riding and indeed touring so much more enjoyable as you can use all the gears. Brompton should really produce their own 39T front chain ring.
I agree. I bought the bike with a 50t chainring, swapped for a 44t one and still wasn't using all the gears. I'm much happier with the 39t solution. I don't mind coasting downhill, with climbing being the priority for me. I've had this on for about 2 weeks now and I'm not switching back.
Doesn't brompton have a 12% reduced gearing option?
@@ultrastoat3298 I believe so. Maybe fitting their 44T or 42T front chain ring is the reduction? Don't know. In any case it wasn't enough for me when loaded up to go touring climbing serious hills/mountains.
@@ultrastoat3298 50T minus 12% = 44T.
Yes, the 44t chainring IS the 12% reduction.
I did this to my Brompton and it transformed it. It came with a 50t so i thought swapping to a factory 44t might sort matters. Nope.
Wish I'd gone straight to a 39t.
I have no idea why Bromptons are so over geared. Even with a 39t, top gear is a little high for the flat. Did a test ride in the Cotswolds on Friday with my 39t and it was spot on. No more getting off to push!
...I just wish i could find a 39t chainring with a bash-ring / chain guard for less than £90!
I got a plain 39t chain ring for £10
I did exactly the same as you. Swapped for 44 first and then went down to 39t. I just came back from tour and the chainring choice was a game-changer for hill climbing.
I've done the same. Very well explained.
Best decision ever.
I've ridden Alpine mountain passes with a 39 T front chainring and I've bike toured with it (tent, mountain pasdes and all).
Yes, on the downhills I spin out but that doesn't matter because climbing that's the hard part. Easy climbing with a low gear that's actually low is what it's all about. A lower low gear is much more "knee friendly" too ;)
Thank you for sharing your experience with a similar setup. I ended up touring with the bike and it was a much improved experience. While the route was mostly flat, the few steep hills I encountered were very doable with this setup and a loaded Brompton. So, like you, I'm happy with this.
Really impressed by your video - clear consise and well explained - looking to do the same - great work, enjoy your touring
Glad you found it useful. I'm on tour right now and the 39t chainring is perfect.
Welcome to the addictive world of the Brompton xxx Love from England xxx
Hello! Yes, the addiction has started. I can see why Bromptons have such a following.
Excellent video!
I put a 39-tooth chainring on my new Brrompton, replacing a 50-tooth (groan!) ring. Works great! I wish I had this video to watch, though, before I made the swap, as it would have been helpful and answered a number of questions. Well done!
Glad for the feedback, thank you. Also excellent to know you made the swap and it's working well. I won't go back to a 50T. 39T is perfect for me.
Very well explained video. Recently bought a Brompton and like you finding it very over geared. Will be making the same change very soon to allow for a more versatile ride. Thanks for taking the time to film. Hope your enjoying your Brompton as much as I do great fun. All the best Pete 👍🚲
I'm so glad to hear you found the video of value! I love the Brompton. It's such a fun bike. I hope you enjoy riding yours as well.
I’m definitely curious on how well the 39 works out. I like the idea of touring on a smaller bike. 🤘🏻🇺🇸🇨🇦🤘🏻
I'll be sharing this info post tour.
In my opinion, if this is necessary is because the gearing of a brompton is not adequate, even in a 6 speed. In my 26 bike i have a 38T (11-42). Requiring a 39T with such a small wheel could only mean that the gear range is narrow and too long.
Great video. Very professional
She missed out the rear bolt wrench, whch is essential
@tonyhopkins4399 Can you expand on your point? Which rear bolt wrench did I miss out?
wow touring with Brompton, I was wondering how that's even better than a touring bike especially if you need to take it on a bus/train/plane with you.definitely a good idea for cross country or international touring, can't wait to watch your Brompton videos,Thanks a lot
I think it'll be a great challenge. I have to consider packing lightly, which will be new for me. 😉 Multimodal travel will be much easier with the Brompton for sure.
Susana Thornton is probably the queen of touring w a Brompton. So inspiring!!
@ShadowWilliams1265 Agreed! Love her videos.
@@WheelsonaBike indeed! Me too! I just purchased my first Brompton as well. C line explorer. I hope to experience some touring too! I enjoy watching your videos! So nice to see you touring on a Brompton! I’m going to be changing to chainring to 44t. Question, do you loose speed when you drop down to a smaller chainring? Thanks!
@ShadowWilliams1265 I can't really answer your question as speed is the last thing I ever worry about and I just don't pay attention to it. I suspect you would loose speed on flats and downhills and you would potentially spin out.
I did the same thing on my Dahon but added the Tern mainstay to keep the chain on the chainring. Without a front derailleur, a guide of some sort, or a narrow-w8de chainring, the chain can pop off on some terrain or when shifting cassette cogs.
There's a tensioner on the chain, so I hope that will keep it on. I've not had any issues with the chain coming off yet, although someone commented that their wife had experienced it.
Thank you for this video and the very clear instructions! I am about to make the same change on my Brompton and this looks to be the perfect step by step guide 👍
Glad to know you found the video useful and good luck with the modification.
This is my first Brompton video,
I have never had the privilege of experiencing a Brompton, although I have seen several E-Brompton commuters going to work at our local hospital and local students and townies running errands in my area of Celebration, Florida.
The Brompton certainly appears to be a very efficient bike and fairly simple to work on and to upgrade..
It is my hope that the wild fires have subsided in your area of Canada, thank you for sharing and stay safe…
There are more Bromptons riding around Toronto as well. Not very many eBromptonzs yet, but I suspect this will change. No wildfires in and around Toronto, thankfully, just lots of smoke at times. But very strong weather systems coming through.
Brilliant acquisition, Agnieszka, and it is a Piccadilly Blue C Line! 🤩I bought this same colour Brompton C Line last year and I absolutely revel in riding it around New York City. I have been riding my steed along the Empire State Trail but nothing as adventurous as your undertakings. Thank you for your inspiring content. Take care! Ta!
Hello fellow Piccadilly Blue-er! It's a beautiful bike and a joy to ride. It continues to impress me so much and the fact that it folds so small only adds to the wow factor! One day, I will continue along the Empire State Trail and ride it to New York. Need to finish that trail. 😉
what trail is that?
empiretrail.ny.gov
@@juan-carlosetxevarria8779 empiretrail.ny.gov
When I bought my 2019 SuperlightM6LXBrompton, I at first wondered for what use I had the - low set of gears, till I met a steep Danish serpentine road, and even had to walk up, for a higher speed! I find my present 6 speed gearing fine for most purposes (I have a selection of other size, front chainwheels also, but I have never changed to any of those!).
But if in need, it is possible to buy a - double chainring in front (And a Changer for the frame), giving 12 speeds, with an absurd changing between the possible gears! I also have some extra size, titanium chainwheels for for my 3 speed gear hub, in other sizes than the original 2. My bike at present weighs 8,5 kilo, with mudguards! Finn. Denmark
There are always options, aren't there? I think if you can tinker with the bike, instead of asking a mechanic to do something for you, that's better, as you can try different solutions and make the bike work for you and your riding conditions. Thank you for listing the available options.
I swapped my H6L to a 44t chain ring, works great there is a noticeable jump from low to high gears though
I initially went from 50 to 44 and found that gearing a bit awkward. The 39 t chainring works much better.
@WheelsonaBike yes awkward might be the right word, just have to pick the right gear
Shimano offers a 39t chain guard and separate 39t chain ring. Just ordered them and hope to install this next week thanks to this excellent video, thank you !!
That's great to know, thank you for sharing the info. A chain guard is always helpful.
Update on the 39t Shimano chain guard, it is for a specific Shimano crank and does not work on a Brompton 😢
PS. I did install the Shimano 39t chain ring, not nearly as smoothly as your demonstration but your demo was inspirational.
@GusGundersen-video Oh... That's too bad. It sounded promising.
@GusGundersen-video you got it done and that's all that matters.
Nice video!🙌
Thank you.
You rock Agnieszka! Have a lovely Sunday, love✨❤️🔥
Thank you.
Love your attitude!
Thank you.
I've been thinking about making the same mod to my 6 speed Brompton. Would love to see more about how you intend to use your Brompton for touring and how you will equip it.
Well, if all goes according to plan, I'll be out on tour in September. I'm sure I'll have a lot of learning to do.
@@WheelsonaBike can't wait to see it. Where are you going?
I'll be heading to the States.
Many thanks for your helpful video. Helped me lot today!
I'm glad to hear that!
Such a well done video
Why didn't you ad the Chain cover again also, if possible (You are able to buy chain rings with an integrated cover)? At least I use pants on my bike. And when first using my 2019 Superlight 6 speed I wondered for what use I had the rather low gears, till I met an absurd hill going up, and had to walk on top! Finn. Denmark 😄
The 39 tooth chainring did not come with a chain guard. I'm not sure any of the 39t chainring do. Someone mentioned a Shimano 39t chainring with a guard in the comments, but then followed up that the guard didn't work with the cranks. I know there's is a 40t chainring that has a guard, so maybe that could be an option for you.
My wife's Brompton has a 39T chainring also. The issue she had while touring was that the chain would occasionally came off the chainring. I believe it was due to the fact that the 39T chainring was meant for a 10 speed chain, so there was quite a bit of side to side play when fitted with the Brompton 8 speed chain. Of course this particular issue went away after I changed the chain to a 10 speed, while adding an extra sprocket gear at the rear.
Thank you for flagging this. Was there a specific scenario when the chain came off? Under torque or just generally riding? Did it start happening right away or do this appear after prolonged use?
Also, can you elaborate on adding an extra sprocket gear? What do you mean by that?
@@WheelsonaBike The Chain seldom comes off but it does, and I don't think the chain needs to be under loaded. As for the extra sprocket gear, you may want to google "Brompton 6 speed to 9 speed". Basically, replacing the stock 2 gears at the rear with 3 gears(10/11 speed), then change the chain and shifter accordingly.
One-by chainring can never support all demands the road will bring, unless there is a Rohloff speedhub in the back. The bicycle will be either sutiable for hills and thus relatively slow or suitable for flat and tail wind. For details, see The path less pedaled channel, or calculate gear ratios. The reason Brompton comes with 50t is most likeky due relarively small wheel diameter....20'' ? If you really like this bike, one (pricey) solution could be Schlumpf Drive unit. They are excellent for trikes and bikes with small wheel diameter.
I realize the limitations, and don't expect the Brompton to replace my touring bike. There are many channels that identify the shortcomings of Brompton one by drivetrains, you mention one, another is 2 wheels 4 adventure who have done an amazing job at bringing a lot of knowledge together.
Thanks for sharing this conversion. Will try it for my touring Brompton where I still have a 44 chainring.
You're welcome. Good luck with it.
@@WheelsonaBike Thanks again, did the conversion last week and after a few test rides I can say it was a good decision 🤙 I also took the time to replace the bottom bracket, instead of the Brompton I now have a metal one from Shimano
how did you know you have to remove 2 links from the chain and not 1 or 4? Is there a connection between teeth and amount of links?
I found this info on a site, which provided guidelines for chain length specific to front chainring size.
Any recommendation for (39T) Model and Brand Chainring? TIA.Ride Safe everyone!
I only have experience with the one I installed and share in the video. Maybe others can comment with their suggestions as well.
I'm already using a 44T on my Brompton and did remove two links on my chain.
If I was to swap to a 39T, do I still need to remove anymore chain links?
I was also swapping from a 44T chainring and yes, I removed two links as a result.
I have a 44t and want to switch to 39t, but somehow the shop in montreal couldn't order one for me, which brand did you use and did you get it in canada?
Thanks for your question. Yes, I bought the chainring from a shop in Toronto. I show the package in the video - it's a SRAM chainring. Here's the exact item I bought www.sweetpetes.com/product/sram-road-inner-chainring-158599-1.htm?variations=617438&catalogTypeId=1
Can you find a chain guard that fits the 39T chain ring?
No idea.
🤠👍
As you already have a touring bicycle, why do you want to tour on a Brompton?
Challenge. Attempting to tour on a 6 speed bike will bring its own set of challenges and I'd like to experience that. Also, I may be taking the train and unfortunately our train system in Canada does not welcome full size bikes on board. They used to, now they're waiting for updated cabins
... So they say...
My tours often start with an airplane, train, or bus. Hence, my Brommie. Good on ya @@WheelsonaBike