I think it's worth noting that the corollary to shorter cranks requiring a higher saddle is that longer cranks allow you to lower your saddle. While that's not usually anything anyone cares about, if you're trying to lower your saddle for cyclocross to make remounts easier, longer cranks might be worth considering.
As a person with a hip replacement, changing to a 165mm crank was a revelation. The change eliminated both on-bike pain as well as post-ride pain in my hip. Sadly, I went through several different bike fit sessions and none of the bike fitters suggested a shorter crank, even when I was on a bike with 172.5 and 175mm cranks. The change that I made to 165 was something I decided to do on my own after a lot of research.
Same here fir my hip replacement. Went from 172.5 on my road bike to 165, much better. 170 on my mountain feels the same, I think the more upright position. I did notice better tech climbing with 170 vs 165.
Great video. I'm 5'3" with an inseam of 29". I recently went from 170 cranks on my size 50 Domane to 160's. I used to get saddle sore type irritation even with a bike fit. Since going to 160's that no longer happens. I feel much more even and stable with no pressure or need to move around on my seat. Thrilled with the change especially with comng up on 8000 miles for the year.
I disagree with your take on Myth #2. As someone living in a hilly area, I very much felt the increased difficulty on steep climbs (>10%) where I was already pedaling at
I concur. If you increase your cadence using shorter crankarms (to maintain the same power), you'll be obligated to climb faster in first gear. But you can't because you haven't increased your power. You need to lower your gearing for the shorter crankarms.
Perhaps it didn't come across this way, but the intended takeaway was that if you find yourself running out of gears based on terrain, increasing the size of your cassette (or reducing chainring size) is the appropriate solution rather than using this as your reason for selecting crank length.
@@larrylem3582 If you increase your cadence on short crankarms, you are not obligated to climb faster (increase power). You exert less force per stroke, since you have less leverage (and thus a lower effective chosen gear), which leads to more pedal strokes to achieve the same wattage per unit of time in that gear. If it becomes harder with shorter cranks, it's because they affected your fit on a different parameter e.g., handlebar drop, center of gravity, saddle setback.
I can remember when LONGER crank arms were the rage. Now the pendulum has swung back. I'd challenge your average cyclist to tell the difference in crank lengths UNLESS they look at what's marked on them. I've been riding for decades and honestly can't tell 170, 172.5 or 175 mm. I wonder if a cyclist had 10 bike fits done by 10 different "expert" fitters - would ANY of them be exactly the same? I doubt it.
We generally find that bigger changes are where the benefits really shine (for riders than need them). Completely agree that 2.5mm can be tough to notice for many riders, but moving from 172.5 to 165 or shorter is often immediately noticeable. One of the challenges with the current offering of lengths from big brands is that they're in such a narrow window.
Thanks for this video. It’s the best explanation on crank length I’ve heard so far and it addresses all the key points/concerns I’ve have about shorting crank lengths. One thing you alluded to which would have been nice is when you said there are certain cycling scenarios when a longer crank are is beneficial but for the average cyclist it isn’t an issue. I’d like to know what the scenario is. Thanks
Thank you we are glad you enjoyed! We were referring to high force/low cadence or peak torque situations. Situations like super short climbs on the MTB or cross bike or some track events with a standing start. It’s arguable though the improvements in those few situations outweigh the other benefits.
Damn, I really need to get shorter cranks. I'm short legged and bought a bike when 175 mm cranks were the industry standard. Whenever I get into an aero tuck whilst pedaling my thigh strikes my abdomen and subsequently I have to reposition myself on the saddle constantly. Although, replacing cannondale Si cranks are 1. out of stock and impossible to find. 2. eye watering expensive at $300AUD per crank arm. Thanks for the info, really cemented the idea I need to change the crankset is worn out.
I´m 185cm tall and normally ride 170mm, but on a recently purchased SuperSix are longer cranks. The owner told me 172,5mm, but i found out yesterday that those are 175mm. This bike rides so much faster, easier and straighter, that i cannot sign the whole "go shorter" trend.
At the end of the video we talked about how "shorter isn't for everyone." If you are comfortable and happy with your position, shorter cranks might not be the thing for you! It is important to compare apples to apples though, a fun new bike always rides faster ;) Congrats on the SuperSix!
As a taller rider who prefers higher cadences (100-110 rpm) on 170-175 mm cranks, I found it impossible to spin 165s any faster (>110 rpm). The smaller circumference and arc length of power application meant I had to stomp hard to turn over the gear, causing my quadriceps to fatigue far faster. Climbing was where this was most noticeable as the increase in resistance made the peakier pedal stroke much less efficient.
Great breakdown! I never thought of the fact that, after changing saddle height to adjust for crank length change, there's a huge difference at the top of the pedal stroke. 2 CM is huge! I'm just glad there's a few bike companies that are starting to spec smaller cranks on everything from medium sized bikes on down. It's been a long time since I've ridden 175mm cranks, but I do remember feeling like they were just way too long. I've also never tried anything shorter than 170, but they feel way better to me than my 172.5s I ran for so long. But I'm pretty sensitive to changes in position. I just recently moved my saddle 5mms forward after feeling like my reach was too far, and my bike now feels completely different.
I agree with the changes to stem length vs moving the saddle forward. However, like the creator of this video, you are thinking one dimensionally. Shortening the crank also impacts the position of the body above the major force production zone of the pedal stroke in the horizontal plane. So reducing crank length by 1cm, should result in a rise in saddle by about 5mm and an increase in saddle setback of a few mm. Taken together this will improve you pedal stroke. After doing this, then figure out your stem length. Every video on crank length ignores the change in knee over pedal changes. The horizontal changes result in a foot position which is much further forward when coming back around the pedal stroke from the 6 o'clock position thru the 11 o'clock position. You will feel this as a reduced force against the power stroke of the opposite foot. It really is a big part of why smaller cranks feel easier to spin and less stressful on the hip.
Chainring size is definitely a factor in MTBs where you get some pretty steep climbs. I live in a hilly area and with a 28t front chainring 165mm cranks I can do most of the climbs staying in zone 2 in the easiest gear when I'm managing my effort. I switched to to 155mm to try and address a knee issue and the extra effort required over the 165mm is definitely noticeable in the legs and is reflected in my heart rate and it spikes into zone 3 more in the really steep sections. Also to even fit a 28t chainring on there in the first place I sacrificed the smallest two cogs otherwise the chain didn't clear the chainstays.
I totally buy all the benefits of shorter cranks, but the loss in torque for me as a bigger rider does make a tangible difference. I'm 190cm tall with long legs. I tried 170s coming from 175. And in my area climbing usually means short steep hills that you need to power over. That's where I just couldn't stand how short cranks felt. I prefer climbing out of the saddle when the power gets high. Shortening my cranks in those situations felt like a loss in torque that I could compensate by shifting into an easier gear. But then again I'd have to do a cadence that I didn't feel comfy with out of the saddle. I really didn't like it. On a TT bike, I'd definitely put super short cranks on no questions asked. But on my road bike it wasn't for me.
The only dimension that cannot be changed is, naturally, the one bike fitters totally omit. If you get this dimension wrong your bike will never go in a straight line without you constantly correcting it up to 30x per minute.
I'm 185cm and use 165mm on all my bikes. Going from 170mm to 165mm reduces the force on the knee joint by 9%. It makes zero sense to go above 165 unless you are being paid money to race.
I went to 165mm from 170mm (5'9'' individual) and ajdusted the saddle height accordingly. Guess what? No more left sided knee pain and I'm holding a 10rpm higher cadence (85-100) much more comfortably. Oh and btw my pelvis in more stable despite not having any real issues with hip impingement, so... Less saddle chafing and less friction = more comfort. I wish more bike fitters were a little more informed and knowledgeable regarding crank length here in Italy... They kinda seem to be stuck in their own ecosystem XD
I bought a fatbike which came with 170mm cranks. It felt very different initially but became more comfortable over time. When going back to my MTB I had a hard time with the 175’s so switched it to 170. I built a gravel bike with 170’s and now my road bike feels weird with its 172.5.
The missing part in this debate is that crank length is proportional to the rider. Tadej Pogacar's 165s and his saddle height scaled to mine for example would put me on 180 mm cranks. Cranks for the smallest riders ideally need to be 140-150mm, and up to ~180mm for the opposite end of the spectrum. Currently, the availability of crank arms and limitations in gearing don't allow this. A 30T low gear at 170mm needs to be 36T at 140mm, and this isn't possible with most road parts. Hopefully we will see a wider range of crank lengths in the future so everyone can have the same riding experience. The standard lengths should drop the 2.5 mm increments and progress like 150, 155, 160, 165, 170, 175, 180. Shimano DA currently is 160, 165, 167.5, 170, 172.5, 175, 177.5.
Good but can your app estimate the angle differences by shortening the crank by, say, 1cm? That would be useful because new cranks are expensive especially if you’re on Red or other…
Myth 2 is not busted… a shorter crank does increase the pressure required to generate the same power - therefore it does make the “gearing” higher. I do agree that with the number, and range of gears we have on bikes makes this mostly irrelevant, but not nothing.
We talked about this in Myth #1 though. Among commonly accessible crank lengths, the biggest change you can make is from 175mm to 165mm. The power increase of 175mm vs 165mm was .35%. It's not a significant enough number to require that much more power where your gear range couldn't compensate for it. Most riders wouldn't be going from the largest crank to the smallest crank either, so the differences would become even less significant.
Another myth to be busted: there is no torque loss on shorter cranks. The torque generated at the hip transfers 100% to the pedal spindle. We mechanical engineers learn this on the second semester. What change is the force reaction, which is what we feel. There is no such a thing as horizontal pedal and a vertical force pushing it down. Things are moving and the torque must be delivered across the whole pedal circle
People who experience "torque loss" were able to deliver the torque effectively on the longer cranks, and now they shorter crank likely reduced the hip extension thus reducing overall power. On the other end, people with shorter legs would not deliver power effectively on top and bottom of the pedal stroke on long cranks, went to shorter cranks, and everything improved. There is no better or worse. There is the better for you.
Nicely explained. I'm 6'2, just changed from 175 to 170 cranks and all my knee pain disappeared and longer rides became far more comfortable.
Best video I've seen yet on explaining the differences in crank length and their effects
I think it's worth noting that the corollary to shorter cranks requiring a higher saddle is that longer cranks allow you to lower your saddle. While that's not usually anything anyone cares about, if you're trying to lower your saddle for cyclocross to make remounts easier, longer cranks might be worth considering.
As a person with a hip replacement, changing to a 165mm crank was a revelation. The change eliminated both on-bike pain as well as post-ride pain in my hip. Sadly, I went through several different bike fit sessions and none of the bike fitters suggested a shorter crank, even when I was on a bike with 172.5 and 175mm cranks. The change that I made to 165 was something I decided to do on my own after a lot of research.
Injuries are the worst. Happy to hear that this has helped and you're able to keep riding!
Same here fir my hip replacement. Went from 172.5 on my road bike to 165, much better. 170 on my mountain feels the same, I think the more upright position. I did notice better tech climbing with 170 vs 165.
Great video. I'm 5'3" with an inseam of 29". I recently went from 170 cranks on my size 50 Domane to 160's. I used to get saddle sore type irritation even with a bike fit. Since going to 160's that no longer happens. I feel much more even and stable with no pressure or need to move around on my seat. Thrilled with the change especially with comng up on 8000 miles for the year.
Amazing! Glad to hear it has worked out for you.
I disagree with your take on Myth #2. As someone living in a hilly area, I very much felt the increased difficulty on steep climbs (>10%) where I was already pedaling at
I concur. If you increase your cadence using shorter crankarms (to maintain the same power), you'll be obligated to climb faster in first gear. But you can't because you haven't increased your power. You need to lower your gearing for the shorter crankarms.
Perhaps it didn't come across this way, but the intended takeaway was that if you find yourself running out of gears based on terrain, increasing the size of your cassette (or reducing chainring size) is the appropriate solution rather than using this as your reason for selecting crank length.
@@myvelofitIf you’re already running a 34 with a medium cage RD, increasing the the cassette size is not an option.
@@larrylem3582 If you increase your cadence on short crankarms, you are not obligated to climb faster (increase power). You exert less force per stroke, since you have less leverage (and thus a lower effective chosen gear), which leads to more pedal strokes to achieve the same wattage per unit of time in that gear. If it becomes harder with shorter cranks, it's because they affected your fit on a different parameter e.g., handlebar drop, center of gravity, saddle setback.
@@marcpost4034 Yeah I'm maxed out in terms of what I can do with gearing on my mountain bike
I can remember when LONGER crank arms were the rage. Now the pendulum has swung back. I'd challenge your average cyclist to tell the difference in crank lengths UNLESS they look at what's marked on them. I've been riding for decades and honestly can't tell 170, 172.5 or 175 mm. I wonder if a cyclist had 10 bike fits done by 10 different "expert" fitters - would ANY of them be exactly the same? I doubt it.
We generally find that bigger changes are where the benefits really shine (for riders than need them). Completely agree that 2.5mm can be tough to notice for many riders, but moving from 172.5 to 165 or shorter is often immediately noticeable. One of the challenges with the current offering of lengths from big brands is that they're in such a narrow window.
I couldn't tell you based off feel if my cranks were changed but my knee flares up pretty quickly if I go over 170mm.
As someone of an average cylist. I can tell you it's so much more comfortable riding a 165mm crank vs 175mm on 100km+ ride.
Thanks for this video. It’s the best explanation on crank length I’ve heard so far and it addresses all the key points/concerns I’ve have about shorting crank lengths. One thing you alluded to which would have been nice is when you said there are certain cycling scenarios when a longer crank are is beneficial but for the average cyclist it isn’t an issue. I’d like to know what the scenario is. Thanks
Thank you we are glad you enjoyed! We were referring to high force/low cadence or peak torque situations. Situations like super short climbs on the MTB or cross bike or some track events with a standing start. It’s arguable though the improvements in those few situations outweigh the other benefits.
@ very helpful and thank you.
Damn, I really need to get shorter cranks. I'm short legged and bought a bike when 175 mm cranks were the industry standard. Whenever I get into an aero tuck whilst pedaling my thigh strikes my abdomen and subsequently I have to reposition myself on the saddle constantly. Although, replacing cannondale Si cranks are 1. out of stock and impossible to find. 2. eye watering expensive at $300AUD per crank arm. Thanks for the info, really cemented the idea I need to change the crankset is worn out.
I´m 185cm tall and normally ride 170mm, but on a recently purchased SuperSix are longer cranks.
The owner told me 172,5mm, but i found out yesterday that those are 175mm.
This bike rides so much faster, easier and straighter, that i cannot sign the whole "go shorter" trend.
At the end of the video we talked about how "shorter isn't for everyone." If you are comfortable and happy with your position, shorter cranks might not be the thing for you! It is important to compare apples to apples though, a fun new bike always rides faster ;) Congrats on the SuperSix!
That's because you are 185.
As a taller rider who prefers higher cadences (100-110 rpm) on 170-175 mm cranks, I found it impossible to spin 165s any faster (>110 rpm). The smaller circumference and arc length of power application meant I had to stomp hard to turn over the gear, causing my quadriceps to fatigue far faster. Climbing was where this was most noticeable as the increase in resistance made the peakier pedal stroke much less efficient.
Great breakdown! I never thought of the fact that, after changing saddle height to adjust for crank length change, there's a huge difference at the top of the pedal stroke. 2 CM is huge! I'm just glad there's a few bike companies that are starting to spec smaller cranks on everything from medium sized bikes on down. It's been a long time since I've ridden 175mm cranks, but I do remember feeling like they were just way too long. I've also never tried anything shorter than 170, but they feel way better to me than my 172.5s I ran for so long. But I'm pretty sensitive to changes in position. I just recently moved my saddle 5mms forward after feeling like my reach was too far, and my bike now feels completely different.
It is a common recommendation to change stem length, not move saddle forward, to change reach.
I agree with the changes to stem length vs moving the saddle forward.
However, like the creator of this video, you are thinking one dimensionally. Shortening the crank also impacts the position of the body above the major force production zone of the pedal stroke in the horizontal plane. So reducing crank length by 1cm, should result in a rise in saddle by about 5mm and an increase in saddle setback of a few mm. Taken together this will improve you pedal stroke. After doing this, then figure out your stem length.
Every video on crank length ignores the change in knee over pedal changes. The horizontal changes result in a foot position which is much further forward when coming back around the pedal stroke from the 6 o'clock position thru the 11 o'clock position. You will feel this as a reduced force against the power stroke of the opposite foot. It really is a big part of why smaller cranks feel easier to spin and less stressful on the hip.
Chainring size is definitely a factor in MTBs where you get some pretty steep climbs. I live in a hilly area and with a 28t front chainring 165mm cranks I can do most of the climbs staying in zone 2 in the easiest gear when I'm managing my effort. I switched to to 155mm to try and address a knee issue and the extra effort required over the 165mm is definitely noticeable in the legs and is reflected in my heart rate and it spikes into zone 3 more in the really steep sections. Also to even fit a 28t chainring on there in the first place I sacrificed the smallest two cogs otherwise the chain didn't clear the chainstays.
Did it help the knee issue?
@@chendy2099 Only just got them, too soon to say
I noticed the same thing
It can absolutely impact your gearing choice. Like most thing bike related, compatibility is often a challenge.
I totally buy all the benefits of shorter cranks, but the loss in torque for me as a bigger rider does make a tangible difference. I'm 190cm tall with long legs. I tried 170s coming from 175. And in my area climbing usually means short steep hills that you need to power over. That's where I just couldn't stand how short cranks felt. I prefer climbing out of the saddle when the power gets high. Shortening my cranks in those situations felt like a loss in torque that I could compensate by shifting into an easier gear. But then again I'd have to do a cadence that I didn't feel comfy with out of the saddle. I really didn't like it. On a TT bike, I'd definitely put super short cranks on no questions asked. But on my road bike it wasn't for me.
That's great you gave it a shot though because it may have helped! Your mileage will definitely depend on you as a rider and your riding style.
I been riding 165 mm for like 9 years your totally right alot better going shorter
The only dimension that cannot be changed is, naturally, the one bike fitters totally omit. If you get this dimension wrong your bike will never go in a straight line without you constantly correcting it up to 30x per minute.
Do you mean like when you're riding with no hands? I do notice that my bike pulls to the left a bit
I'm 185cm and use 165mm on all my bikes. Going from 170mm to 165mm reduces the force on the knee joint by 9%. It makes zero sense to go above 165 unless you are being paid money to race.
That's awesome! Glad to hear it's been working out for you.
I went to 165mm from 170mm (5'9'' individual) and ajdusted the saddle height accordingly. Guess what? No more left sided knee pain and I'm holding a 10rpm higher cadence (85-100) much more comfortably.
Oh and btw my pelvis in more stable despite not having any real issues with hip impingement, so... Less saddle chafing and less friction = more comfort.
I wish more bike fitters were a little more informed and knowledgeable regarding crank length here in Italy... They kinda seem to be stuck in their own ecosystem XD
I bought a fatbike which came with 170mm cranks. It felt very different initially but became more comfortable over time. When going back to my MTB I had a hard time with the 175’s so switched it to 170. I built a gravel bike with 170’s and now my road bike feels weird with its 172.5.
The missing part in this debate is that crank length is proportional to the rider. Tadej Pogacar's 165s and his saddle height scaled to mine for example would put me on 180 mm cranks.
Cranks for the smallest riders ideally need to be 140-150mm, and up to ~180mm for the opposite end of the spectrum. Currently, the availability of crank arms and limitations in gearing don't allow this. A 30T low gear at 170mm needs to be 36T at 140mm, and this isn't possible with most road parts.
Hopefully we will see a wider range of crank lengths in the future so everyone can have the same riding experience.
The standard lengths should drop the 2.5 mm increments and progress like 150, 155, 160, 165, 170, 175, 180. Shimano DA currently is 160, 165, 167.5, 170, 172.5, 175, 177.5.
Also reduces toe overlap w/ front wheel…?
It absolutely does. For many riders it won't be enough to eliminate it, but it can help.
You nee to select women’s bike for that.
Good but can your app estimate the angle differences by shortening the crank by, say, 1cm? That would be useful because new cranks are expensive especially if you’re on Red or other…
hmm, but you need to accelerate upto any rpm, so I think you'll definitely feel it being more difficult getting upto speed, on shorter cranks.
But your pedal velocity increases which would help with accelerating up to a desired RPM.
Myth 2 is not busted… a shorter crank does increase the pressure required to generate the same power - therefore it does make the “gearing” higher. I do agree that with the number, and range of gears we have on bikes makes this mostly irrelevant, but not nothing.
We talked about this in Myth #1 though. Among commonly accessible crank lengths, the biggest change you can make is from 175mm to 165mm. The power increase of 175mm vs 165mm was .35%. It's not a significant enough number to require that much more power where your gear range couldn't compensate for it. Most riders wouldn't be going from the largest crank to the smallest crank either, so the differences would become even less significant.
Another myth to be busted: there is no torque loss on shorter cranks. The torque generated at the hip transfers 100% to the pedal spindle. We mechanical engineers learn this on the second semester. What change is the force reaction, which is what we feel. There is no such a thing as horizontal pedal and a vertical force pushing it down. Things are moving and the torque must be delivered across the whole pedal circle
People who experience "torque loss" were able to deliver the torque effectively on the longer cranks, and now they shorter crank likely reduced the hip extension thus reducing overall power. On the other end, people with shorter legs would not deliver power effectively on top and bottom of the pedal stroke on long cranks, went to shorter cranks, and everything improved. There is no better or worse. There is the better for you.
It’s physics and optimal biomechanics yeh?
And what about tall gays ...> 190cm ? .... .. 165mm. 🤔
Shorter is relative to the rider. Lots of riders at 190cm on 165mm on TT and tri bikes, but what works for you is personal.