Moving to shorter crank lengths

[satanas]

People vary a lot. Some are sensitive to crank length, and others don't notice quite big changes. So, the only way to find out what suits *you* is to experiment, and that will take time and/or money. You may need to adjust the gearing when crank lengths change, or not.

FWIW, I started on 170mm BITD, then had 180 on the first MTB (never got used to them), then 175mm a couple of MTBs later, after which I decided to try and split the difference with 172.5 on the road bike and felt instantly at home. Since then I've been using 172.5 on all bikes with freewheels, including MTBs where possible. With 170 it's easier to spin stupidly fast but torque is lacking, and with 175 there's more leverage but less comfort and spinning is harder. For me - YMMV! - 172.5 is the best compromise. Along the way I also tried 178 briefly on a MTB (good for climbing steeply off-road, but terrible trying to spin on the road), and 165 on a fixed gear commuter (no power, reverted to 170 for fixed); 172.5 on fixed felt like my legs were going to be torn off.

I can see using shorter cranks to facilitate a TT/tri position, or for pedal clearance on DH MTBs, etc, but not so much elsewhere. The only way to know for sure is to try a range of cranks, and to find which ones are too long and too short for you and what you're doing!!!

[ViperFFM]

180cm
84cm inseam

165 cranks on all bikes because of the better hip angle; no more weird feelings down there

[warthog101]

184cm tall.
Raced tts on 177.5
Faster for me.
Ride 175 on my roadie.
Tried 172.5 and climbed marginally slower.
Perhaps I could try them again or go smaller but cbfed.
175 is comfortable and works for me.

I'm the same height, and use 170mm across on road and gravel, 165mm on TT.
It's very individual.
The only way to really find out what works for you is by testing - riding hard for sustained efforts.
I got a lot of practice and data when racing TTs so it was very easy to tell shorter is fast for me.

Yeah I found the opposite, shorter definitely slower for me on TT.
I climb slower on them too.
Still able to spin a 175 at mid 90s cadence and the hip angle wasn't causing me problems.
It is individual it appears.
Had a quick look though, Filippo Ganna, Rohan Dennis, Tony Martin, (Fabian Cancellara 177.5) all tt'ed on 175 and they seemed to go alright.
I no longer race apart from the occasional gravelly but 175 still works.

[tmanley]

I'm not sure if this makes much difference, but I'm pretty tall, 187cm, so I'm well within the fit window for 175s.

Where did you find the fit window? I'm 198cm so 175mm cranks might even be small for my height!

I'll share my experience - I'm 207cm and used to ride 180mm cranks. Now riding 175mm and they feel much better - for my TT bike I'm going to try 170mm.

[vgcl]

I'm 1.88m with 87cm inseam (6'16" / 34.25"), and I need a lot of saddle seatback to compensate my short legs. Always used 175mm because it's what came in the bikes my size. I think it feels to large and don't cope well with saddle far back that I need. I'm building a new bike and thinking about skipping the 172.5 and going directly to 170... What do you guys think?

[StanleyM]

in effect...crank length is just a gear ratio change mechanically speaking. If your strength and joint angles are fine at your chosen crank length, all is well.

[ViperFFM]

If you dont have any issues; dont change it.

Moving to 165mm eliminated some pains in the dick area for me.

[vgcl]

If you dont have any issues; dont change it.

Moving to 165mm eliminated some pains in the dick area for me.

I get some pain/discomfort in this area after training, and tightness when spreading the legs. It's similar to the pain you are describing?

[TobinHatesYou]

in effect...crank length is just a gear ratio change mechanically speaking. If your strength and joint angles are fine at your chosen crank length, all is well.

1) Raising the saddle and even pushing it forward slightly will likely allow you to keep a flat back without your knees knocking against your chest at TDC.
2) Shorter cranks afford you a couple degrees when pedaling through corners.
3) Shorter cranks are stiffer and lighter
4) Shorter cranks are less likely to have chain and chainstay clearance issues. I have to add a minimum of 2mm in pedal spindle washers with Garmin Rally/Vector pedals so the threaded portion doesn’t hit the chain in 52x11.

The extra leverage of longer cranks is an advantage is in standing starts…and only for an instant.

[Mr.Gib]

I miss some things about my 175mm cranks. I was always comfortable with that length but decided to go to 170mm to profilactically protect my knees (there's a lot of bad history there). What I miss most is the leverage during out of the saddle efforts: powering over rollers, some sprint situations, some climbing situations. OTOH, I do enjoy the additional comfort in lower aero postions that shorter cranks provide. And the knees have been good for the last decade.

[TobinHatesYou]

My 5s power is exactly the same on 165s with my cleats slammed backward as with 172.5s with cleats in a more neutral mounting position.

I'm considering trying out Croder Spirit crankarms+spindle in 150mm or even 145mm.

[TobinHatesYou]

I'm considering trying out Croder Spirit crankarms+spindle in 150mm or even 145mm.

Decided to test the limits and ordered 140s. I suspect it will end in tears, but there’s only one way for me to find out. In my head, I think I can at least go down to 155mm though. I’m 177cm with an 80cm inseam and excellent hip/back flexibility. With longer cranks and a short saddle height, I definitely feel hip impingement at the top of the pedal stroke. I tend to compensate by putting less weigh on my ass and more on my hands and legs.

[Hexsense]

subscribe to the topic.

I have an idea to order Ti gravel bike, which allow custom geometry.
Currently, I run 165mm crank on all bikes (road, gravel, XC) and I don't have pedal strike on road bike with 74mm drop.
So...
With tall gravel tire, maybe, if I go 155mm crank I could get away with 90mm bb drop on the gravel bike. That's an option.
But let see other's feedback on shorter crank first.

[TobinHatesYou]

subscribe to the topic.

I have an idea to order Ti gravel bike, which allow custom geometry.
Currently, I run 165mm crank on all bikes (road, gravel, XC) and I don't have pedal strike on road bike with 74mm drop.
So...
With tall gravel tire, maybe, if I go 155mm crank I could get away with 90mm bb drop on the gravel bike. That's an option.

I can pedal strike easily with 165s on a bike with 70mm BB drop, though I also run my Garmin Vectors/Rallys with either 2-3mm in pedal spindle washers depending on the bike. I had to replace one DS RS body because I shaved away so much material that the battery compartment was no longer sealed and the yellow o-ring would squeeze itself out the hole.

[Hexsense]

Eh well, maybe 85mm drop then.
On road currently I use Speedplay.
So, Gravel bike's spd with mtb shoes which has walking tread would have less cornering clearance, even with 155mm crank.