[Donkeeboy]

Especially since that tree has got to be the coolest around...I absolutely don't care about what cranks OP runs, but will forever be ruined to all other trees.

It is a cool tree, that’s what prompted the picture. It clearly was popular, the bark was worn from people sitting on the natural bench.

 

[yzedf]

You lose about 3% leverage for every 5mm.
So the difference between 150 and 175 will be about 15% leverage, which translates into a lot of leverage/power loss.
You are going to have to rotate 15% more and going to have to do 30% more pedal strokes.
An hour ride doing 60 rpm's is going to be 3600 rpm's and 7200 pedal strokes.
With 150mm cranks that is going to be 540 more rpm's and 1080 more pedal strokes.
There is a reason most all top XC men racers run 175s and lots of top women XC racers run 175s and almost none run anything lower than 170s.
You lose power/leverage with short cranks and they make you slower.

No you don't. This has been studied over and over again.

For a recent one man test by someone that sells cranks:

Case Study 01: Crank Length VS Power and Cadence - Appleman Bicycles

Good article with links to numerous studies over the last several decades:

Crank length: Forget leverage and power, it’s all about the fit

It’s almost inevitable that every road cyclist will start to wonder about the crank length they are using. It’s a topic that is surrounded by a lot of

velo.outsideonline.com

 

[Grinchy8]

the margin where a longer crank would allow me to grunt max power piston style up a hill is the margin my 50+ knees want to stay far away from.
I don’t have a strava account and could care less how long a ride takes as long as I’m enjoying it and working hard.
When it is too steep to ride comfortably I get off and walk.
I often ride with others, and I can tell you walking isn’t much slower than the hamster wheeling in 30x52. And you absolutely don’t need ‘longer’ cranks to push that gear ratio, you run out of cadence or can’t stay upright against the grade first.
The gears where ‘extra leverage’ would make a difference are gears I’m too unfit to find myself in.

but my knees and hips (shorter cranks means less hip angle) are quite happy with my decision.

 

[Bikedog22]

I ran these 180mm E13 cranks for 17 years on my SS. Not too bad with pedal strikes over the years.

The only reason I pulled them was the bolt started coming loose every 100 yards. I never looked into the cause. Now I'm on on some 175 Turbines I found on Backcountry.

I didn't go out of my way for 180mm cranks. I won them in a race raffle so why not?

I haven't had short 165 cranks since the DH race days with 200mm of travel.

 

[Hurricane Jeff]

Want are the problems that you all are running into using 175mm cranks? I'm 5'11, have a 32" inseam and have been running 175's for as long as I can remember. I've tried 165's, 170's and 172.5's but always returned to 175mm cranks for some reason or another. I'm known to produce lots of power and can spin a very high cadence as well as mash the gears. I do not see any negatives with 175's, which I run on my enduro bike, single speed, XC, gravel and cross bike. I realize that we are different and what works for some, may not work for others.

 

[turnerbikes]

More fuel for the fire?!

 

[ilmfat]

More fuel for the fire?!

 

[turnerbikes]

Un-scientific thoughts on MY SS and MY crank length... I am not sure crank length is as important on my SS as my geared bikes because for all hard work I am standing. My lack of efficiency/lack of power have me standing a lot on climbs, a lot. So, with my hip angle very open, my upper body able to sway up and over the pedals, cranks that might be too long for my geared bike are not even noticed on the SS. Until I sit down, at this point the little bit longer crank length is noticeable. Years back during a period of short crank blah blah blah, I dropped from 175 on almost all my bikes to 170, but one of my SS still has 175 and it definitely feels too long now. 5 freakin mm's. Who woulda thunk it.

DT

 

[ilmfat]

Want are the problems that you all are running into using 175mm cranks? I'm 5'11, have a 32" inseam and have been running 175's for as long as I can remember. I've tried 165's, 170's and 172.5's but always returned to 175mm cranks for some reason or another. I'm known to produce lots of power and can spin a very high cadence as well as mash the gears. I do not see any negatives with 175's, which I run on my enduro bike, single speed, XC, gravel and cross bike. I realize that we are different and what works for some, may not work for others.

When I (5'10") first got my TJ (175s stock), I had some pedal strikes. So I went 170 and strike rate went way down.

Flame me for using bandaids to compensate for poor technique, if you're inclined. Idgaf. I ride rigid. I'll merely reciprocate and point out suspension is a crutch, not a tool.

On the Dartmoor, BB was low. And I had a Spawn 160mm crank laying around. So it went on. But Henchladies have ridden the Primals w 165 and 170 and had no complaints. So the 160 is likely overkill. And feels it when swapping back and forth.

Riding pie plates has killed my power far more than 10 mils of crank length change.

 

[9Major]

I think crank arm length needs to fit you body type and riding style. I'm tall and when I ride my SS, I mash a lot. My trails are punchy and a RPM in the 30s is typical for the punchy climb. I want to torque up them, yanking on the bars. The top speed on the trail is just about where I spin out, So longer cranks arms are better for me. If I was riding trails that I could keep a constant 90 RPM cadence, then shorter cranks might be better.

Geared bike will be different as cadence is more uniform.

 

[Varaxis]

Recall the times you tried pedaling with the seat lowered too much. If you think of that in terms of biomechanics, a reasonable conclusion would be that your strongest leg muscles, made to extend the leg, have much less mechanical advantage when the knee is bent more.

Also, your body intuitively knows that it has better mechanical advantage when the foot is closer to being under the hips when trying to extend it. Try climbing a staircase in a "tucked/crouched/jackknifed" cycling position, with the feet ahead of the body/hips; it's very hard to fight the intuitive urge to get hips aligned straight over the feet.

Try timing rapid ascents up a flight of stairs. Repeat a few times. Notice what technique the body prefers when trying to manage stamina and muscle strain/fatigue. Cycling is a cardio sport, not resistance training.

Anyone who bothered to go through all this, with their brain actually using its critical thinking ability, might be able to link the conclusions with crank length. Bonus if you actually remember taking physics related to mechanical engineering in school, and learned that gears/cogs are levers too.

 

[mack_turtle]

could care less

I automatically disregard anything you have to say.

 

[Grinchy8]

I automatically disregard anything you have to say.

My wife kids friends and coworkers already in that club. Don’t take the internet from me too!

 

[tom tom]

I have ridden short cranks for the past fifteen years. I first started playing with crank lengths as a mountain unicyclist because it was the only way to change leverage ratios other than changing wheel size.

On muni I rode crank lengths ranging from 75mm to 180mm, ultimately settling on 150mm cranks.

Fast forward a few years, I went back to riding bikes and I carried on with the short crank mentality, running 160-165mm cranks on all my bikes and tandems.

After building up a full suspension single speed, I decided to make a crank length change, going from RF 165mm to Trailcraft 152mm cranks.

I’m a few weeks into the change and so far I have felt no loss of power, in reality, I feel like I’m riding faster and my pedal turnover feels quicker.

I doubt I’d ever go shorter, having played with crank lengths for years while riding muni, I found then as I find now, that the ideal crank length is ~150mm.

View attachment 2122350

When I was 3 years old, I had 152mm cranks on my tricycle......But now that I am all grown up, I use 175s!!

 

[ilmfat]

When I was 3 years old, I had 152mm cranks on my tricycle......But now that I am all grown up, I use 175s!!

Our groms had pedal strikes on their tricycles with 152s. So we went 130 and they were much happier.

 

[9Major]

Recall the times you tried pedaling with the seat lowered too much. If you think of that in terms of biomechanics, a reasonable conclusion would be that your strongest leg muscles, made to extend the leg, have much less mechanical advantage when the knee is bent more.

Also, your body intuitively knows that it has better mechanical advantage when the foot is closer to being under the hips when trying to extend it. Try climbing a staircase in a "tucked/crouched/jackknifed" cycling position, with the feet ahead of the body/hips; it's very hard to fight the intuitive urge to get hips aligned straight over the feet.

Try timing rapid ascents up a flight of stairs. Repeat a few times. Notice what technique the body prefers when trying to manage stamina and muscle strain/fatigue. Cycling is a cardio sport, not resistance training.

Anyone who bothered to go through all this, with their brain actually using its critical thinking ability, might be able to link the conclusions with crank length. Bonus if you actually remember taking physics related to mechanical engineering in school, and learned that gears/cogs are levers too.

I found a great technique for better mechanical advantage....Its called standing up...

 

[In2falling]

"A bike cassette provides mechanical leverage by allowing the rider to adjust their gear ratio based on the size of the cogs on the cassette, essentially giving them more power for climbing hills"
"the greater the mechanical advantage and lower the required force to pedal"

🔼Mechanical Advantage/Leverage = 🔽lower the required force to pedal

 

[Varaxis]

"A bike cassette provides mechanical leverage by allowing the rider to adjust their gear ratio based on the size of the cogs on the cassette, essentially giving them more power for climbing hills"
"the greater the mechanical advantage and lower the required force to pedal"

🔼Mechanical Advantage/Leverage = 🔽lower the required force to pedal
View attachment 2122514

Now take this knowledge and apply it to the crank (and wheel size). It factors into the final gear ratio, when you combine crank, chainring, cog, and wheels.

In other words, discussing crank length leverage is akin to arguing cog or chainring size. Going down 10mm in traditional crank lengths (170 to 160) is similar to going up 2t in traditional chainring sizes (30 to 32t).

What chainring did the OP drop down to? 26t? If they were running 30t before, and went from 172.5 to 152, they'd have the same gearing, but would benefit from the better biomechanics and ground clearance with crank at 6 o'clock. RPM increases naturally due to the feet having to travel less distance to complete 1 RPM, due to the smaller circumference. If the feet cover distance at a rate that's no slower...

 

[Varaxis]

I found a great technique for better mechanical advantage....Its called standing up...

You get more efficient at what you repeat. Spending 90+% of the time standing on the pedals will make you a legend at it, contending with people who spend 90+% of their time seated on the pedals. Wasn't there some legendary roadie who did this, despite so many claiming seated was more efficient?

Considering how many people lose noticeable watts going from a slack STA bike to a steeper STA bike, before adapting to the new STA, it's quite impressive that ~150 cranks show no noticeable loss, despite the clear difference in technique. I imagine that once someone gets used to the new technique, they very well might become faster. XC racers have historically been the slowest to adopt all sorts of change that might discount the athlete's 1000s of training hours.

 

[Donkeeboy]

Now take this knowledge and apply it to the crank (and wheel size). It factors into the final gear ratio, when you combine crank, chainring, cog, and wheels.

In other words, discussing crank length leverage is akin to arguing cog or chainring size. Going down 10mm in traditional crank lengths (170 to 160) is similar to going up 2t in traditional chainring sizes (30 to 32t).

What chainring did the OP drop down to? 26t? If they were running 30t before, and went from 172.5 to 152, they'd have the same gearing, but would benefit from the better biomechanics and ground clearance with crank at 6 o'clock. RPM increases naturally due to the feet having to travel less distance to complete 1 RPM, due to the smaller circumference. If the feet cover distance at a rate that's no slower...

Hi there!

I didn’t change my gearing, just changed to shorter cranks.

I rode this morning, cranking through turns, without a thought of pedal clearance, it was so nice 😁

This is an interesting discussion for sure, kinda makes me giggle when folks talk physics and engineering.

Do you all know the difference between a carpenter and an architect?

The carpenter builds the house so it’s structurally sound, architects dream about what the house would look like if cost, physics, and gravity didn’t matter 😍

If you want evidence based knowledge, there’s only one path in this instance ….