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- เผยแพร่เมื่อ 31 พ.ค. 2024
- Considering short MTB cranks? Watch this first. Here's a non-sponsored take on mountain bike crank length. I've spent a considerable time on 170, 165, 160, and 155mm cranks, and I'm nice and opinionated on where I think the industry should be heading with MTB crank length.
I'm well aware that the only brand shown here are 5Dev cranks, but again this is not a sponsored video. I just like their cranks personally, and we do sell them out of our shop. The options are quite limited at the moment for cranks below 165mm, and 5Dev make a solid option. One thing I really like is the removable spindle on their cranks. This is handy if you have 2 bikes with multiple hub widths (i.e. regular Boost 148 spacing MTB and a fat bike with 197mm spacing, they offer different spindles so you can just have one set of high-end cranks for both bikes.
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Short Video Supplement: • Should you be running ...
Here's a link to the study discussed in the video: www.ncbi.nlm.nih.gov/pmc/arti...
Timestamps
0:00 Intro
2:36 Science Breakdown
9:50 155 vs 165 Trail Test
13:00 Conclusion - กีฬา
![Stop This 1 Humiliating Jumping MISTAKE with these 3 drills [CRITICAL Safety Advice]](http://i.ytimg.com/vi/TgGeZZYB068/mqdefault.jpg)
Wow man. This video is great. Well done. We can confirm we had no part in this video. Super cool the algorithm led us your way this morning. 🔥🔥
👊🏼👊🏼
I ride your 145s. I'm 6'2" and tried 5 sizes from 153 to 130, mostly cut down sram cranks by Bikesmith Design. I got several friends on shorter cranks, one buddy on his Bosch ebike with 155s from you. All of them are faster riders now.
As a fellow PT and mountain biker with short cranks, I gotta say I love this video. Nicely done!
Thanks for the kind words 👊🏼
I switched from 175 to 160 and I feel it's night and day better. Besides the advantages mentioned in the video I have noticed that riding while standing is vastly improved. it's so much smoother and more in control. the transition from siting to standing is much smother. The main reason I'm so pleased with short cranks is that my knees are damaged and painful, but the pain all but disappeared after I switched.
Well done. Over the last two years I have gone from 175 to 165 cranks. I also switched to an oval chain ring, 32 teeth. Great combo where i do most of my riding in Vermont. Soon to be 73.
Awesome, keep shredding!
😋
Great video! I got some sweet Hope purple 155 cranks, replacing 165 on my Turbo Levo. Wow! Smoother, almost “luxurious “ pedaling, knee pain gone, right inner hip pain leaving. This is insane, bike companies couldn’t care less about fit!
I'm 6'2" tall with 34" inseam. I switched from 175mm cranks to 165mm in hopes of reducing knee pain. That was successful and I found that my rides were not as exhausting as they were with the 175s, as you mentioned. I agree with most of what you said except for two exceptions: 1) When torque and power matter the most, I am off my saddle, just like you were in riding portion of the video, and the opposite of your indoor demonstration. When standing on the pedals, I can move around so that I can get my bodyweight going through the ends of the cranks with hips and knees not nearly as flexed as your indoor demonstration shows. That gives the longer cranks a torque advantage. With the shorter cranks, I've adjusted my attack strategy for the steep uphills. It's not necessarily more difficult; it's just different. 2) Having the feet closer together in the fore/aft direction does not provide more stability. For me it is definitely a less stable posture. And if using flat pedals, the rider must press the fore foot forward/heel down and the rear foot aftward/heel up to stay connected to the bike when off the ground or rolling through rough terrain. With shorter cranks, the feet are closer together and the angle makes it more difficult to maintain proper contact.
I will keep the 165s on my bike. The benefits outweigh the disadvantages for me, even though I have to ride more carefully on the janky trails that I love and not boost so hard on the jumps.
Thats odd. Im 6'3 with a 36.5 inseam.
My road bike has 180mm cranks. Love it. Borrowing a MTB with 170mm cranks. Road yesterday I got some knee pain today on the top of the knees .
@@Southerncyclist If you are pedaling while sitting on the saddle, you have to raise the saddle to compensate for shorter cranks. Dropper posts are usually set up so that the top of their range is about the same height as a road bike's saddle height. Running cranks that are 10 cm shorter will force you hips and knees into greater extension. If that bothers you (it bothered me), you have to raise your saddle so the to of its range is 10 cm higher.
@@jimwing.2178 ya man I raised the seat like 1.5 inches from where the owner had it lol.
ABSOLUTELY THEE BEST EXPLANTION on this debate (so far). I think I can finally decide on a length and feel like I made the right choice.
Im 6=4 or 194 cm. Run 175 on trail bike and 180s on XC rig. Tried 170s and hated them. 51 years old been riding MTB for 31 years.
I'm 195cm. What is your inseam?
So I can only speak for myself about this, but I ran 165 cranks on my bike and just could not get used to them . I'm 6 ft tall and whatl bothered me the most was I had to raise the seat post and I just felt too high on the bike. And I could definitely feel the shorter pedaling circle and it felt weird to me.
I find off road you want to go as long as you can for those grinding portions, without it being too short you can't spin.
I'm 5'10" with 31" inseam, 170 works well for MTB but 165 does too, especially an e bike since you just need to move your legs to get the motor going.
For a fixed position like road or time trial you'll want efficiency and aerodynamics, so even shorter works even better. Hip impingement meant swapping over to 165mm from 172.5. pretty much solved the issue overnight.
So I moved from 175 to 170 on the MTB and found it raised my saddle up, making the long travel 26" hardtail ride like a horse! Swapped out that to a better bike has transformed my riding (along with 29 wheels!)
My comfort level is massively improved with shorter cranks but I do think there is a limit!
Great video! Love seeing local content like this. I plan on trying the 155 cranks on my ebike first and go from there. Thanks for sharing your thoughts on this subject.
Very interesting and informative video. I may just have to give these shorter cranks a try and see how it feels.
Thanks mate for bringing this up
I ride a Salsa Mukluk fat bike doing trail work in the National Forest. I am regularly carrying tools that cause the bike to weigh 70 lbs on average. I switched from 175 to 165 last year and have never looked back. I’m 6 feet tall. Game changer! Let pedal strikes, better climbing ability, hips and knees feel great. Will be switching my other bikes as funds allow. Thanks for the video!
Thanks for the real-world feedback! And thanks for your efforts on trail work 👊🏼
I was expecting reduction in knee pain but the total lack of hip and lower back pain after I switched from 170 to 160 cranks really surprised me. Should’ve done it years ago.
Fat bike for the win 🤙. They are great bikes and perfect for rolling and smoothing out trail that has been rutted up by “pizza cutters”
My surly Pugsley weigh that much without tools
Great video….. I’m 6’2 and ride 155s on my bullit and love it! Also at 54 years old I wish I had gone with shorter cranks long ago
Great real world relevant information, not just charts and time on a trainer. I have a 29" inseam and I have always just ridden the 175's that came with the bike. I think that I want to try 155's because of my inseam and the fact that I have strong legs. Now I just have to find out if I can rent the cranks near me. I might just end up making them in the CNC here at work. Great job on the vid and now as a new subscriber i'll look through all of your content.
I started riding at age 54 with an emtn bike.. this was informative. Thank you.
I have been thinking about trying shorter cranks as I am 5’6” with a 30” inseam. This video just solidified that desire. Your background in PT helps explain a lot of what I experience with longer cranks (175mm)
I'm 5"7'. 155mm cranks on the gravel/all road bike have been very helpful for nerve pinching and hip issues. They may not make me produce more power; but my average speed has increased. I'm thinking of changing the cranks on the fat tire bike as well.
Did you do it? I have same measurements
@@omarcervantes9752 I have not changed the length of the cranks on my fat tire bike.
Well done Sir!!!! I recieved my 155mm cranks a few days back getting ready to install them on my MTB. old mtb gets relief!! 30 inch inseam!!!!😀
Great video. This has been this best video explaining the benefits of short cranks I've seen. And being someone that has lower back pain from time to time the more upright position caught my attention. Gonna try some shorter cranks. Thanks again, good stuff
Thanks for the kind feedback and enjoy the cranks!
You have presented solid evidence from many categories of what the crank arm does and can do, both positive and negatively, by being shorter and longer. You've sold me! Now, I want to find my perfect shorter length crank rather than accepting the previous status quo. New journey!!😃
This is the best video I've seen on this topic. Thank you.
You killed it with this video!!
Great job man!!
👊🏼👊🏼
I recently put 155s on my park bike.
First impressions are no negative effects, more confidence and I don’t feel like I’m stretching out each stroke.
It’s winter so I haven’t gotten to fully test them yet but i already know I’m going to love it. Will likely get another set for the emtb
Hope you enjoy them! I love mine.
motocross has both pegs at the same spot.. no trouble with it. i use 155 on the parks and downhills, too. i have a 30" inseam and prolly could have gotten away with 150's
im tellin ya, shorter cranks improve jumping. ;)
great job! very helpful!
Great video my Farley 7 and Roscoe both have 1x12s lots of power shorter would sure be to my advantage I had negative thoughts about short but it all makes sense I had both legs broke about a inch below my knees thanks for the info.
Very interesting! Always thought that messing with crank lengths is something I shouldn't consider as barely a weekend rider, but this certainly got me thinking. I'm 6' 3.5" and fatbiking, but still.
Thanks, great thought process..I do get some pedal strikes and I prefer smaller chainring around 30-32 tooth. I think I’ll try the 155 length also because I’m same..5’8” 30.5 inseam ..I’m pretty sure I’ll get results!
This is all great information, but you left out the fact that however much the crank is shortened, the seat will have te be raised by the same amount. I went from 170 to 165 and I had to raise my my seat 5mm to have the same knee angle at full extension. I feel way more on top of the bike. Its fine, but I cant imagine going another 5mm higher on my saddle hieght. Also, the higher the seat, the longer the effective toptube length will be. The effective seat tube angle will be slacker as well. Im not saying dont do it, but theres a lot more to it than just saying samller circles = better.
Hopefully MTB companies will study the effects of shorter cranks on Geometry and adjust accordingly. Hell if 160mm becomes the new norm, every company can lower thier BB hieght making, thus lowering the center of gravity.
I thought about the effective seat angle as well. If I were to raise my seat any higher than it is my weight distribution would be way too far back on the bike especially with my chain stays currently at 415mm.
Sounds like a lot of thought went into your explanation. Lol. If it’s better for you, then it is! There is nothing wrong with finding the best solution for your situation. I haven’t switched yet, but I’m gonna definitely switch. Appreciate everyone’s input for sure!
Pushing your saddle forward on the rails can help compensate often.
Shorter cranks, LOWER your saddle so leg extension at BDC is the same!!!
This is incorrect. You should always measure saddle height center of BB to top of saddle across all bikes regardless of crank length. The circle you pedal is a virtual center so the angle of knee will naturally become less the shorter the crank. Do not lower the saddle as you are adjusting your body position.
Awesome stuff Dr J! You swapped the 170s for 160s on my Rise before it even left your shop. My thinking at the time was purely less pedal strikes but now I'm convinced it was the way to go for a lot of reasons.
Hope you’re loving the Rise! Thanks for commenting 👊🏼
Shorter cranks on a Rise let you get more out of the motor. It's tuned to give maximum power in the 90rpm range. That high rpm is easier to maintain with shorter cranks.
@@tonyrobinson1623 Very solid point. I knew they were tuned for higher RPM, but hadn't even considered that is a benefit of shorter cranks.
This is great! Solid explanations and arguments.
MTB Alan! Thanks man 👊🏼
@@DrJMTB 🤘🏾😄
Excellent video bro! You need more subscribers with content this good! 👊🏼
👊🏼👊🏼
so helpful. I torqued my knee at the beginning of the season and currently looking for shorter cranks. So hard to find a reasonably priced product is hard.
Oh Man finally got my 155mm mtb on my Vitus installed Man what a change they are a great change,specially now that I,m getting older!!!! man can i spin so much smoother!!!! 30 inch inseam glad i didn't go with the 160mm!!! thanks again😃!!!
155mm Hope here too , burning legs in long descents are past now . Almost no pedal strikes also Pedaling uphill didn’t change at all (with an enduro 170mm bike ) so never going back to longer cranks .
Thanks for sharing 👊🏼
Me neither! Going back I mean 🤙🏽🤙🏽🤙🏽
I didn't realize how important this was until I got a full sus that came with 170 mm cranks. I never got tired knees, had way better balance, felt stronger on long ascents, and just all around loved the feeling. So I switched out my fat bike cranks to 170 mm also, and added a 28 tooth oval and now it climbs like a beast too. I'm female and 5'6" but mostly annoying long legs so for me this really dialed my bikes. Once you change, you aren't going to believe how much of a difference it makes.
Went 155 Canfield cranks when they were the only player on the market.
Now 155 Hope going on the new enduro, I'm never going back to "standard" crank length.
I’m 5’8” and have shorter legs with a 30” inseam. I strained my patellar tendons last year when my dropper post sunk into my frame. It’s been a long year but I’m looking into this theory HARD! We tune EVERYTHING else on the bike.
Feet placement on pedal might be another thing to consider with these experiments. I tend to stomp and put it way behind the ball of the foot around the middle when it gets tough uphill, then near my toes when its high speed and manageable.
Foot placement for me is more than going from 165’s to 175’s for sure. Just looking and my mtb cleats vs my gravel bike shoes/cleats shows well over 15mm of difference. Mtb stand and mash shooter cranks my cleats are more mid foot, sit and spin longer cranks on the gravel bike cleats are more on the balls….. end result same stance
Your take on spec'ing small and medium bikes with 170mm and up cranks is exactly what I've been ranting about to my friends, lol.
I'm 5'6", and my knees love the 150mm cranks vs the oem 170mm. And I could probably go shorter!
I too, have experienced all the positive results you have highlighted.
Thank you for updating what I think is an important topic.
Thank you for your kind feedback and glad you’ve benefited as I have 👊🏼
What did you do with the seat Hight after swapping ? read stuff on this that seams to conflict..............
Seat height comes up a bit, because the bottom of your pedal stroke won't be as low as it was with longer cranks.
Follow a tutorial on finding the proper form, then tweak it to your liking.
I think I have my seat height set your proper leg extension, but I rarely ride any parts of my local trails at full extension. I like to sit in the bike, feels good to me.
Lol, I have rode Dollar Hill a few times at Pulaski County park. You make it look easy compared to me. This video is great and very informative.
Thanks for giving folks some perspective on Dollar Hill, Chad! Swing by and see us in the shop!
Apologize if I missed it, but something I don't think you mentioned was the fact that if you shorten your cranks, you have to raise your seat by the same amount to maintain correct pedal to seat height. This now goes against what you were saying about rider comfort for shorter cranks because you are now having to lean more since the seat height increased but your bar height stayed the same, adding more work for your lower back and weight on your wrist/handlebars. I'd rather have more leg movement vs throwing my back out.
Aww man! That climbing test has got me thinking hard now about 155mm cranks now. We have a lot of short steep climbs like this too where I ride. just got a set of x01 165mm for my Spur (size small) and noticed a big difference going down from 170mm. The only thing I don’t like is sensation of a higher BB/ less “in” the bike. I wonder if it’s worth going even shorter. Hey 5dev, take my money!
Been racing MTBikes since 1987. Watching video of me racing looked terrible, and I felt that way. Ten years ago I had a machinist shorten my cranks to 135mm. I tried adjustable crank arms from 90 mm to 175 mm Decided on 125mm for the road bike and 135mm for the MTB I think maybe 130 mm would be best for me. I love my shorter crank arms. Everyone always bring up the leverage point. They just don't undrsatand. Great video! Thanks Also I'am 5' 1"
Awesome story. Sounds like you were ahead of the curve on shorter cranks!
Yeah sure 😂
just as your giving your answer i had the same thought damn , im building a new bike now lol , thank you , iv dislocated both of my knees in high school 20 yrs ago and ive been trying to figure out the upper patella pain on 4rh or more rides , ill try this .
just got a new e road bike, a creo Small with 170mm stock. First thing I did was order the shortest cranks I could find that fit, a 165. Will continue to look for shorter ones like 155 or 160.
I’ve wondered how we got here with these long cranks. Tables show I should use 165 or 170 cranks but M size production bikes come with 175. The S size bikes my wife gets come with 170 cranks - she should have 155. Interesting to note that my 1986 size M Specialized HardRock has its original 170 cranks. I can maintain a higher continuous speed on this 38 year old bike than I can on my modern hardtails. It is clear to me that the insignificant lesser leverage of my old shorter cranks is surpassed by the greater power I can sustain over time due to not losing as much energy in the excess articulation of my legs. I fully concur with all of bio-mechanical points explained by the good doctor. So,,,,somebody in this industry used to know better. How did we all get stuck with excessively long cranks in recent decades? Shorter cranks X millions of bikes per year would be a noticeable $ material savings for the manufacturers. Why have they been over spending to provide us with less optimal crank fits when it could save them money to give us the proper sizes?
Thanks for the practical feedback! And I agree, the industry needs to take note!
Great video mate! One formula from another mtb channel suggested the length of your inseam in mm x 0.2 will give you a good starting point for crank length. You can always go shorter. So for me, I have an 810mm (32in) inseam and my crank length according to formula is 162mm. I have 170s on my fat bike now but it was the shortest cannondale made. I have 160mm on my tri bike but one of my best Ironman races I did on 145mm cranks.
I have read something close to this. They recommended 0.21 or 0.216
Nice, where do I get 195mm cranks? 😂
Excellent info
Great content
Great points. I prefer them for the reduced pedal strike and chances of catching a pedal at high speed. In addition helps me ride in a higher cadence that is not only better for my E bike motor, but seems to help with momentum on the non-Ebike.
So funny how you posted this video now. I just bought a new Specialized Epic EVO Pro in a medium and just noticed that they spec’d this model with 175mm cranks? The other EVO Pro Lrd. Has 170 mm cranks, so not sure what they were thinking. I have a 30” inseam and usually do better with 170mm cranks and have not ridden 175’s on a Mtn bike since the late 80’s/90’s. I pick it up tomorrow. Hope it will not get too many pedal strikes!
They put on the cranks they had at the factory the day they built your bike
@@stevem4838 ....or that's part of the sale price. If I can't sell them, I can get another set of 170's for $300. I'm still just over a $2K discount on that bike.
I rocked from side to side on the seat and had sore legs from over flexing. Cheap REI bike has incompatible bottom bracket so I had to chop down 175 to make 156mm. Immediately felt better and started making climbs there were impossible before. But then I buy 29" inseams 'cause I can'g find 28". I run 32T on my hardtail. Two years later and I'm still thrilled.
I changed my whyte e180 165mm cranks for Hope 155mm, forced to change due to bending a crank arm on a huge pedal strike, but since the change I rarely pedal strike but had to raise the dropper by 10mm to compensate, quite a big change of feel of the bike but they work well.
Thanks for sharing. It would seem radical to anyone who hasn't struck a pedal on an eMTB, but my opinion is that no e-bike ridden in the woods needs longer than 155mm. May do a dedicated video on this. Hope make some nice looking ones, too.
The same thing here, 5'10. I spent $20 total drilling, re-threading, and cutting my 175mm to 155mm. ZERROO pedal strokes were reached. Simple to clime.
175mm cranks are NOT necessary for mount bikes-absolutely not. 👨🔬🚳
Very good information. Hopefully I can a lbs to help in this process. One thing that I am curious about is any changes that you may have made in overall seat height or use of your dropper due to the closer stance
Very interesting, i was just thinking about this! Ive never been picky but ive always favoured slightly shorter cranks given the option. Too short does actually feel a bit off to me though due to the short stance. Maybe because i have a background in skateboarding and snowboarding im used to a wider stance.
This was fantastic, I need to give shorter cranks a try (also a benefit for us with bigger bellies)
👊🏼
Just stumbled across your channel, I’m originally from Oneida , good ole clay county , havnt lived there since 2014 but got your channel on my suggested, so are you saying at 5’10 I should be running under 160s wish more bike shops did rentals like that for sure !
TN native myself 👊🏼... Again, I wouldn't say that I'm making any definite recommendations for anyone specifically. If you are used to 170s or 175's and getting along great, you could always start with a cheaper set of 165s that are available in the cheaper offerings from SRAM or Shimano. It gets more expensive when going below that. You're basically my height, and my gut tells me that 155m-160mm wouldn't be too short if you didn't mind the more radical change.
I started running 150mm cranks at 5'11" 2 years ago for tuning bike fit that included chopping 25mm out of my seat tube to keep a 170mm dropper and reducing pedal strikes. I was already running 32T oval chainring. Bike fit perfect, pedal strikes all but disappeared and I found I liked spinning smaller circles. Then I see YT blow up with crank length videos over the last year LOL
Great video. Some intersting points. I wonder how it is swapping back and forth between different lengths. Id like to try but have a mtb , fat bike, gravel bike and a road bike. How long did it take to get ised to them? Ive got 30 years of 175s in my legs and am obvs very fussy on even smalll change in seat height. But i love your analogy of the bike geometry early in the video.
Great thoughts and question! As I mentioned, this was not a brand plug at all, but one thing I do like about the 5Dev cranks is they have removable spindles which means you could have a Boost hub spindle and a fat bike spindle and 1 set of cranks if that was of interest. I did slowly acclimated to 165->160->155 after riding 170s for years. I would be nervous for anyone jumping from 175s to 155s as IT WILL FEEL WEIRD. If you're abundantly used to 175s and having no major issues, I'd consider starting with 165. That being said, an open mind and willingness to experiment will allow a rider to adjust in 5 rides or less in my humble opinion, even if going shorter than 165.
The torque ratio is the same for 130-180mm cranks- get the shortest crank possible for the style of riding. 165mm, 28t front crank with an 11-50t cassette on AL hardtail, is a climbing beast in Western Colorado. 170mm on the road bike and 170 on the ATB bike. 29.25 inch inseam.
Certainly an interesting topic for debate. I get both sides. I do feel like I'm almost slugging my pedals around a wider circle and waiting for the other leg to engage sometimes. I'm tempted to try a 160mm. I also think running flat pedals like I do will be more beneficial with slightly shorter lengths.
Very cool, I’ve often wondered if shorter cranks would help me. Quick question though, what is the pullover you’re wearing and where can I find it? Thank you 😊
This is great conversation and demonstration. I am also 5’9” and 31” inseam. Not a mountain biker but ride bikes everyday. I am most interested in converting the crank arms on the bikes I ride for more than an hour on the ride to 160 or less. Commuter bikes that are less than hour are going to have to wait. The Rando and touring bikes need to be in upgrade que.
th-cam.com/video/nGWFAkoFRvg/w-d-xo.htmlsi=W5uEciDzdgnH9Hc0. I’ve been running 160mm on this Santa Cruz gravel bike with great results. And that does include frequent road rides as well. 👍🏼👍🏼
Great deep dive. Matt Appleman who is 6'2" says he uses 145mm cranks. I've changed my cranks to 155mm and never be looking back.
I had to switch back from155 to 175..too much pressure in a small section of my knees....needed to spread it through all my knee instead of in the apex of the stroke.
155 to 175 is a huge change. 175 to 165 is a much more reasonable place to try.
@@JesseStarrPhoto had profile mini ti cranks on my mini hutch....so tried them. Good for ebikes and dh bikes becauseu don't pedal much at all..but trail to road...u need a bigger rear cassette to equal proper sized crakes.
And the cadence to match feels like my knees are flying off the hinges . 170 I even notice it ...and not just on climbs..I'm sticking with what works.
@@jasonkroll2735 ok. If that works for you, great. Most people we fit with reasonably shorter cranks see a lot of benefits in road, mountain, and gravel.
I am using hope 155 mm cranks and I'm happy with them
I'd love to hear your opinion on 165 with round chainring vs 155 and oval chainring.
Great video Dr. J! Just wonder if the 175mm cranks on my new Epic EVO will equalize my shorter femur/tibia length with that of a bigger rider with a longer femur? Curious as to why no 172.5mm cranks are offered on Mtn. bikes instead if 175’s?
One study found that when the shortest femur tested riders where compared with longest femur rider both using 170mm cranks, there was only 0.5% difference in power output. That is the same study that people base the 20% of inseam for crank length guideline, over this small a difference in max power.
I'm not sure about less than 165mm cranks (I'm tall, 192cm, use max size on pretty much anything), but I was told repeatedly that I wouldn't notice switching from 175mm to 170mm cranks and they were clearly wrong lol.
It's subtle, I don't think I'm more capable with either, but the shorter cranks reduced knee stress and my hips and allow me to ride for longer.
I struggled immediately with knee pain going from the previous gen patrol with 175 arms to a spire with 165. I agree entirely with what your say here but I think my brain was/is hardwired with the type of power delivery you need for 175's, struggled for a while to just pedal smooth to avoid overworking/missfire. Otherwise most comf platform to pedal on, insane traction over rough ups with short arms. Great vid!
Certainly going to take some getting used to for most when changing more than 5mm instantly. Glad you’re getting along great, the Spire is an awesome rig 👊🏼
First Dylan Johnson, now you. I guess I better join the club.
Seeing a 5DEV crank on all your bikes means you are *very* convinced.
Or you have good taste. Maybe both.
I’m 6’0” and I swapped 170mm cranks with a 32t chainring to 152mm cranks and 30t chainring on my enduro bike. Experienced all the positives you outlined in the video.
Great, but inseam length is more important than overall height in determining crank length.
@@jayanderson6016 My post was intended to highlight that you can go even smaller on crank size than stated in this video and is purely subjective. My inseam is 33".
Just changed my 170 cranks for 150, just fantastic..
Another aspect that I feel makes this even more viable is wheel size. The first thing I noticed after years away from cycling, was with 29er wheels and how important it is to be consciously aware of keeping the pedals in motion while riding uphill. The split second you stop pedaling, it both stops more rapidly as well as it takes more effort to get going again than with smaller wheels. Of course I've also gotten used to using 29er wheels now, but the physics will still be there.
I got a bike with a too low bottom bracket for the terrain and riding I use it for, so I am going to swop out the standard 175mm cranks for 165mm cranks this years. For me it's primarily to avoid crankarm and pedal strikes, but I am interested to see the differences in feel during motion.
As I mentioned, I believe most people will be quite safe in trying 165mm. Happy riding!
Excellent video. Curious your DPT opinion on what length you’d suggest I drop to? 52yo, recently diagnosed with osteoarthritis and torn labrum in R hip, MTB actually makes it feel better. Riding 170mm. TIA
Thanks! And it''s tough to give a specific recommendation, but if you're used to 170mm and riding actually makes it feel better, I wouldn't go crazy. If you are inclined to try shorter, grab some 165mm in a SRAM or Shimano cheaper version and see how you get along. If you love it, you might enjoy going even shorter. Shorter will definitely take some strain off from your hip. Let us know how you get along!
6'1", 33" inseam and switched to 165s on my MTB and will never ride longer cranks again. Interested in trying 160 & 155. Easier to climb, way easier to start going fast, plus more control in technical situations.
I, too, am long in the leg, short in the torso. Also, I'm a roadie, but I'm interested in the topic. Like many of us, I'm likely on frames a bit small for me, compensating with stem, post and crank. One of my roadbikes is larger, and in my opinion, looks too big for me. However, when I ride it, I can't ignore that it feels great. We road guys like to slam our bars low so everyone (no one cares) knows you mean business. This positions the legs for efficiency. But if yer thighs are cramping your abdomen and touching your ribs on the upstroke, you fatigue. You can really breathe on the slightly bigger frame. Then you can run a shorter crank (less weight, less energy loss from perpendicular flex to BB). A shorter crank is safer, where even 5mm shorter arms allow several degrees of additional lean before pedal strike. My right foot has never been the same since I crushed it between a tree stump and my pedal. I was on a short section of single track, riding platforms. On the downstroke, my right foot caught a little stump about 6 inches high. My pedal planted on the stump with my foot under it. My momentum ensured the cranks completed their rotation, launching the bike upwards. I was kinda torn off the bike, my big toe knuckle bearing all my weight under the pedal, also stretched my ankle really awkwardly. These were 175s, had I been on a shorter crank, I mighta missed it. Had I been riding clipless, might have been worse? Don't know. But, on this topic, I concur, riding a crank that's appropriately short is better. Riding fast on single speed road bikes requires long periods of higher RPM spinning. Knees flying all over the place from too long a crank arm also presents an efficiency loss, aerodynamically, mechanically and ergonomically. All this said, and only being my opinion, I also agree the differences are not so great as to keep you off a bike. Most of these discussions arrive at similar conclusions, we are usually arguing over single digit wattage gains, mere seconds on race day, and après ride bragging rites.
Physics says higher stability will be obtained from a wider base. The whole feet closer together=better cornering, and more stability is a real head scratcher.
The base is the wheels on a bike, not the feet?
I have a 32.5" seat height and 35-36" inseam. What should my crank length size be?
The golden rule for crank length is 20 - 21% of inseam.
I have a 34" inseam and my ideal crank would be 172.7 - 181.35 mm.
The actual ideal crank length for Dr. J would be 157.5 mm - 165.35mm.
I'm quite happy with my 175 mm , but would probably do fine with 172.5 - 180mm cranks.
Just curious, where do you get that golden rule?
172 to 181 is a huge range for crank length.
I am 5'3"m going to 145 mm cranks. Even moving from 170 to 165mm cranks has been amazing. I believe shorter cranks would be lovely on road bikes too.
I’ve been running 160mm on my Stigmata gravel/road rig with no issues 🤙🏼
Great perspective on the topic! 👍👍 Recently went from 170 to 160. Immediately missed the extra leverage. But within a couple weeks I was spinning up hills faster and easier than mashing up. Actually feel the “spin in circles”. Knees are very thankful.
I like your perspective and I also take a similar perspective as a 25 years experience RN and mountain biking.
For reference I’m 5’6” and have a 29” inseam. I’m also 155# very fit 32” waist and gym 4 days a week and ride 3 days a week. I use a power meter on my gravel bike and have been using Polar and Garmin heart rate monitors for 15 years.
My point is “one size doesn’t fit” so to GENERALLY choosing a shorter crank based on biomechanics does make sense. But in doesn’t apply to everyone. Additionally longer cranks on a gravel bike that you’re going longer distances or a long distance trail rider with gain benefits from running longer cranks if their legs are conditioned to those cranks.
Did you mean to share your crank length?
@@xophere my Hardtail Mtn bikes and SS HT Mtn bikes plus gravel bikes are all 170mm.
I’ll probably get 160 or 165mm on my next trail/enduro bike. But I would never consider a 155 or 150.
E-bikes have a motor so short cranks are only going to be a benefit. You’re not using your muscles or biomechanics to optimize your acceleration.
Thank you for this, the squat example was helpful visualization. I'm a similar height(hair under 5'9) as you with 30.6 inseam. Both my bikes have a 170mm(one from the factory the second I based off that). I was thinking 165mm on my repalcement mtb, but this video has me thinking maybe I should be looking at 160mm for it. I assume a lot of what you mentioned also applies to gravel/rigid mtb riding, correct?
Thanks for the kind feedback and for your question. I've got some of the 5Dev 160's on my Santa Cruz Stigmata as shown here... th-cam.com/video/nGWFAkoFRvg/w-d-xo.htmlsi=MY6Pihag9VuAa7lS. I have two wheelsets, one shoed with road tires and the other for gravel. I love the 160's when doing dedicated road rides, and love them even more when off-road.
@@DrJMTB it sounds like I should test out 160mm then. Thank you
I went from 175 to 165. I wanted to do 160s but the cost options were just out of my range. I like a lot of people overlooked crank length forever. IMO there are no downsides to specing a crank for your proper leg length/ height range
I work in the industry and 100% agree with this. My boss and I have had many long rants to industry reps about how speccing all sizes of these modern long, slack and low bikes with the same 170mm crank arms flies in the face of proportional bike fit. How can it make sense in any capacity to spec a Shimano XT 170mm crank on both a XS bike and also a XL bike of the same make and model? Even here in Australia it is nearly impossible to buy 165mm cranks from Shimano as they generally only keep stock of 170 and 175 versions. I have a pair of 165s on back order for myself on a large size frame, and am trying to find a supplier for 155 or smaller cranks for my partner who's on a small size frame.
Ended up here after pondering whether I'd be better swapping my 170mm for 165mm. In this the 165s are "long" ones 😂. A good part of my thinking was less pedals strikes on lumpy and rooty trails.
Great perspective, but as a 6'4" man i thinl that 175mm is the same for me as you 155mm cranks as far as climbing goes. My daughter 5'5" will benefit from this! I like the thought of the closer stance.
My single speed has 170 cranks and an oval ring to apply more torque at low rpm. My geared bikes are slowly changing over to 160’s, but with multiple bikes it’s expensive.
@DrJMTB
Hi mate ! :) great video thanks, I’ve been wanting to experiment with shorter cranks for some time now but I’ve been struggling to find some « reasonably priced » ones. I don’t feel like buying some 5devs just to experiment. Do you have non e-bikes cranks to recommend that I can find in 160mm ? I found some 155 hope that I could try, but same problem, it’s quite expansive just to try. Thanks ! 🤟
According to SRAM, you can run their 160mm gravel DUB Rival cranks for MTB. The problem is, you’ll have to source an 8-bolt chainring (Wolftooth) for their Rival cranks. That and Canfiled are the only 2 real viable options I know of. Problem with Canfield is that if you’re currently running SRAM DUB bottom bracket, you’ll have to but their BB as well.
@@DrJMTB thank you for your precious input ;) 🤟☺️
If you got knee problems, you may want to go with shorter to avoid bending u knees more than you want to as your peddling, especially if using a seat dropper
Excellent video!
Will have to disagree with the point on hip/knee bend with longer cranks because, as you shorten crank length, you raise seat post. This would effectively keep the same bend, right?
Thanks! And no, that's not correct. By raising the saddle height, you maintain the same angle of your knee in the pedal revolution where your knee is as close to the straightest (most extended) point. At the most flexed point, the shorter cranks will have you less flexed (bent) in both your knee and hip. If you ever try shorter cranks, you'll feel the difference immediately. The black Norco Fluid shown in the video came with 175mm cranks stock, and it's actually crazy how much this is noticeable. In other words, the radius of the circle is shorter (with shorter cranks) and can't push your thigh up as high on the upstroke of the pedal revolution. Lowering your saddle or running longer cranks would have the same effect of increasing knee and hip bend.
@DrJMTB I hear ya, but again you're talking about less bend flex with shorter cranks without adjusting saddle height. Agree if you don't adjust saddle, then shorter cranks would result in less bend at top of stroke. You can demonstrate this just by lowering saddle with whatever cranks are on the bike. Less leg extension at bottom of stroke = more bend/flex at top of stroke.
However, in order to maintain proper saddle height / leg extension, then you'd ideally raise your saddle to accommodate shorter cranks.
I'm far less qualified around biometrics than you are though, so this is just my opinion 🙂
@@kez2252 Regardless of whether your raise your saddle or keep it at the same height, your hip and knee will flex fewer degrees than with longer cranks. Raising your saddle will decrease the bend in your hip and knee even further. Try standing and imagining a pedal revolution in the same way I illustrated it in video.
One thing that’s not really spoken about is that the shorter your cranks (even for shorter riders) the more difficult it is to run enough saddle setback behind the bottom bracket. With the current trend of steep seatpost angles on mountain bikes, you have mutually exclusive things happening. I’m 170cm tall (5’-7”), 77.3cm inseam (30.4”)-with longer relative femurs to tibia, I have difficulty running enough setback with certain saddles on dropper posts even with an XC oriented bike (Trek Procaliber), 170mm cranks is the shortest I go with to avoid my knee going over the pedal spindle. With 165mm on my road and gravel bike, I can just about get my knee about center to 5mm behind the pedal spindle. Any position forward of that on road or mountain makes my knee hurt at threshold pace.
Great explanation. Question-Why do most XC bikes large and up come with 175 cranks. I’ve also noticed most pro xc riders have 175 cranks. Can you give an explanation?
When you find out, let me know. I bet you’ll see them transitioning to shorter soon
I have been on this path of finding an effective pedaling. I have gone with a 165mm cranks and didn't find a difference in power. I did find nothing but benefits. My bike has a 73 seat angle (SA) and I compared it with my 77 SA @ 170mm. I after using 175 on the 73 SA I do have great clearance. In result, I got my son (8yr old) a crank with options of 127 and 152mm. He found it easier to sprint on the 127. I am curious to go with 160, 155, or 150 cranks.
Thank you
My bike came with 175mm stock, I changed that to 170mm and felt the improvement, now considering either 165 or 160mm but maybe going 160 is a little extreme?? Im 172cm tall
I am 5.5 and I use 170mm ... I try 165mm but I couldn't generate enaught energy because of too short torque ... I prefer 170 or 175mm
What about when oval chainrings get added to your shorter cranks ?
170mm cranks here. I personally feel pitched forward/having my weight higher up when running shorter cranks. I like the feeling of a reasonably tall bb with the body still low above the ground.
I do notice a slightly more upright feel with the shorter cranks, which I prefer when pedaling. I’m always standing when hitting anything rough though, so this feeling goes away when standing for me