173 v. 178 Crank Arms?

[Matthew Williams]

Hi everyone,

I am considering switching my crank arms. My existing arms are 173; I’m thinking about going to 178. Here are the existing specs:

Bike: Appaloosa 58cm with 700c wheels
PBH: 90.5
I’m 6’ tall and I have long legs.

Here are my questions:

1: Will 178 arms work on my bike, or will I not have enough ground clearance?

2: Why was the bike originally built with 173 arms? Is it a standard/average size, better ground clearance, better fit for the average user, toe-hitting-the-front-wheel, or another reason?

3: Is the 173 v. 178 difference so minimal that I won’t notice it?

As always, your experience, wisdom, advice, and opinions are appreciated. Thanks, everyone.

[brendonoid]

I have 180mm cranks on my 58cm Appa and 178mm on my 57cm appa. Clearance is not a problem with the caveat that I run 29x2.1 tyres and don't do crazy single track on those bikes. Crank length is 100% personal preference and opinions will vary wildly.

Biomechanics says shorter cranks should be 'better' but I've seen experts also disagree on that. It is a rabbit hole to go down but there is a lot of info out there.

I've tried a lot of stuff over the years and have found I prefer shorter cranks on road bikes and longer cranks on off-pavement bikes, which is counter intuitive but has more to do with posture/hip angles and personal preference.

[brendonoid]

Oh and don't forget to adjust your saddle height by the same amount you adjust your crank length.

[Mackenzy Albright]

I'm 6' 1" give or take with a 89.5pbh. 've ridden 165-180mm cranks. My preference is typically 165-170. I like the pedal clearance and prefer higher cadence riding. I generally get used to whatever I am riding though. No science based or anatomical insight, but I feel like outside of marginal gains and maybe physiological anomalies ones body will adapt to whatever. 

I wouldn't over think it. If you want some new cranks and got the cash, why not give it a try. 

[Garth]

Save your cash . 

I'd ask why are you considering longer arms ?  

My experience with longer cranks(up to 185mm) is that they didn't live up to the promise the crank length theories based on leg dimensions claimed. Theories are theories after all. The opposite way works for me. Foot further forward of the axle and much shorter arms(150mm) works brilliant for me. Ease of leg speed and leverage. I'm not alone in this discovery of course, it's just that it doesn't fit into any of the en-vogue formulas, so few bother to challenge it. 

[Stephen]

My experience with crank length is that it is not very noticeable. I think I have the 173 silvers on my appaloosa, have 175's on my ram, and also have 165's on another bike. I ride flat pedals all the time and tend to adjust my foot position slightly throughout rides, probably more noticeable clipped in. At this point I'd say I'm partial towards a shorter crank (I like the 165-170 range, personally I would'nt go above 175) to avoid more pedal strike, but it also depends a little on the bike. Shorter cranks raises your saddle a little, but again, its all very slight. I think I've even seen Will in a riv email say that crank length doesn't matter that much/don't overthink it..

for reference I'm around 6'2 with a 92ish pbh, I ride the 60cm Joe. 

-Stephen 

[R Olson]

Matt,

There's a long thread on the i-bob group site on this topic as well.  I just bought some longer cranks (my PBH is 91 and I'm 6'2") - riv is selling 184's now, so I got some.  I went form 175's to 184's, so a bigger jump that what you're looking to do.  It's slightly noticeable.   I do like the longer ones better, but it's probably personal preference.  Most noticeable aspect is a slightly lower cadence, which I personally like, but it doesn't make that much of a difference tbh.  I had 178's on a 58 cm appaloosa I used to own so it should fit fine (if memory serves, I think I actually sold that frame to you several years ago, lol).  Currently, I have 178's on my Clem L (in addition to the 184's on my Roadini) and don't have any problems with pedal strike.  Just don't pedal through corners.

Ryan

[Brett Callahan]

Is toe overlap an issue for you on this bike? Would it be if you added fenders? Do you ever intend to add fenders? 

I think the other arguments in this thread, both pro and con, are articulate. Personally, I hate to overlap and would make my decision based on whether this will make it a problem, or worsen a problem. 

[D D]

I’ll second Brendan’s input. I’m also running 178s on a 55cm Appaloosa with 700c wheels in the 2 inch range. No problem with clearance. 

Dustin

On Apr 13, 2023, at 12:55 AM, Mackenzy Albright <mackenzy...@gmail.com> wrote:

I'm 6' 1" give or take with a 89.5pbh. 've ridden 165-180mm cranks. My preference is typically 165-170. I like the pedal clearance and prefer higher cadence riding. I generally get used to whatever I am riding though. No science based or anatomical insight, but I feel like outside of marginal gains and maybe physiological anomalies ones body will adapt to whatever. 

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