170mm Vs 175mm Cranks

Main Mountain Biking Single speed

When I first built up my Red Rocket Single Speed, I used 170mm cranks. I emailed a few guys and they all seem to give me some scientific and mechanical input as to why the 175 would be better. But I didn’t listen.

During my first ride, I didn’t feel any difference at all. So I stuck with it until my next ride, a 12 miler. Man, by mile 4 I was already worn out from spinning too much with the 170. I was completely miserable the whole ride.

So yesterday I finally swapped out the cranks for a 175mm set and boy I can feel a HUGE difference in the power, cadence and my energy. I can REALLY tell that the 175mm makes a big impact on my riding.

Now I’m wondering if 180mm would be better…as Jeremy likes to say, “Bigger is always better.” Kinda makes me wonder if that goes the same for crank arms…

RL Policar

RL Policar is an avid mountain biker and the Editor In-Chief of MtnBikeRiders.com and BikeCommuters.com. Between the two sites, he's published well over 4,000 articles (and growing).


10 thoughts on “170mm Vs 175mm Cranks

  1. you have Strong knees!! 180mm cranksI can’t ride cranks longer than 170mm on any bike.

  2. crank length is usually more for proportioned to your leg and what you’re used to. smaller cranks are better suited for spinning (i.e. road)

    going between bikes with different crankarm lengths a lot can feel wierd.

    you might be better off with 172.5

  3. The important thing is that you don’t have long legs…and I’ve seen photos. If you were endowed with walking sticks like Gabriella Reece or a pro NBA player, I’d say go with 180s. Otherwise, stick to 170/175. Believe me, all the differences you felt were in your head.

  4. Let him go to the 180’s and he can put some $ in the orthopedics bank account.

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