Shorter cranks for my Radial 360

I went for a nice 10.5 mile ride today on my Radial 360. I’ve been all-muni all-the-time lately so it was a pleasant change of pace. I completed the ride in an hour flat, but I was wondering what I could do with shorter cranks (currently has the stock 150s). I use this uni exclusively for road/distance rides.

In the back of my mind is setting up this uni for the Ride The Lobster 2008 race.

How hard is it to adapt to the shorter length cranks? How much harder is it to climb hills with them?

I’d like to hear from the distance riders among us for suggestions on length, brand, Q-factor, etc.

The ones I’m considering are these, in a 125 length. They look nice and light, and they’re very reasonably priced. They have a Q-factor, but it seems minimal. Should I consider even shorter ones?


Those are the exact same cranks I ended up using on my homebuilt 29er. I got 'em in the 152 length and the quality seems very good. As for length, I can’t really say. I just bought a Nimbus 36 w/ 150s and that feels OK to me. I’m not the best climber so I don’t think I’ll be going any shorter for a while. The 150s that came with the Nimbus are perfectly straight thus keeping the Q-factor to an absolute minimum. It’s got the extra wide hub and I’d hate to have my feet any further apart. I’ve read lots of post from people who ride 36" unis with 125s and even 110s. Let us know what you end up with.

My 29er has 125mm cranks. It honestly took about 5 minutes to get used to them. I’ve never rode a 36", so it may be slightly different. Your first mount will feel extremely weird. When I first mounted my 29er with 125s I rode a very wobbly 10 feet and then fell. After that, I knew what to expect and rode fine. I had to relearn idling which took about 10 minutes.

Mostly your cadence will be a little low for the first day, but after that you’ll be completely used to it and will love your new found average speed on the 36.

Get these. i have the 125’s on my coker and they are very light and very nice, and they are 4 dollars cheaper!


Hmm. That is an excellent suggestion. I think I’ll have to do that. No Q-factor at all on them? Should I go for the 114s?

About 25mm, I guess.

To really know you’ll have to try them out. I’d start with 125s, then give them plenty of rides to get comfortable with them. That’s the shortest size I’ve used on Coker, but some top riders use shorter. It depends on personal taste, brakes or not, and the hillyness (hilliness?) of your terrain.

I’d also go for the non-Q cranks. That’s what I’m used to.

Heh, heh. I’d say you were a funny kid, but we’re the same age.

Sounds right.

You could go for 40mm cranks like Brian MacKenzie uses on his Coker.

yebbut…that’s practically a BC.

My friends coker has 110s on it. I really really like them. Maybe you should try 114s for more hill climbing ability.

does anyone make 120s?

On my GB4 36, I’ve experimented with four crank lengths: 150, 170, 140, 130, in that order, although I’ve gone back and forth with the 150s a couple times during the mix. I’ve kept detailed records throughout on both Average Speed per ride, and Average Top Speed per ride. Here is the net of all that, in chronological order, followed by my recommendation:

Crank Length…Number of Miles…Average Speed…Average Top Speed
130…264 (plus more)…10.11…14.08

Key Learnings:
–Shorter crank lengths help you go faster, both on average and in top speed
–Spending some time riding long cranks helps your spin technique, which makes you faster when you go short again (JC theory, confirmed)
–Every time you go shorter, focus on the same training rides, and keep working the hills until you can climb the same steepness with your shorter cranks you could do with your longer cranks. It WILL happen if you persevere.
–The long cranks like 170 are best for climbing ONLY when you’re on hills that are not steep enough to require you to stand out of the saddle. And with longer cranks, the steepness you can take before that happens is steeper than with shorter cranks. But once you have to stand up, 140s or 150s rule. The 170s are harder to get full circle.
–Just go shorter…you will adapt. I ride 130 more than anything now, although I still like 150 or big climbing days. I was lucky enough to get a set of PDC’s tri-tapped Kookas, so I can switch lengths easily mid-ride. I go back and forth between the 130 and 150 all the time. I’ve used the 170 once, and don’t see it much in my future.

Hope this helps.

Ok, for normal use I use 90mm cranks, when it’s windy or more hilly terrain I switch to 102’s, when I trained for Switzerland and when I’m training in the Velodrome I use these lovely 80mm Alu koxx cranks: I couldn’t find them on, must be out of stock.

Don’t be scared to use short cranks, I always advise people to buy a whole set of these cranks: because then you can really find your favourite size, say you like 114’s best, then you can look for a more expensive alu crank if you want. If you buy the more expensive 125mm/114mm crank now and find out you didn’t like them you spent 14 euros for nothing. Also, the lighter cranks reduce the rolling mass of your coker, when you have a heavy wheel it wants to keep rolling, you’ll have to do less, in theory. My advise is to try out the standard steel cranks first, start with 125, and go shorter till you think “Thats it!”



Myth Busted!

That might be true if you’re going downhill on very short cranks without a break, yes. On the flat, no. With my 80mm cranks it’s impossible to get the same top speed as on my 90mm cranks, I have done 39.3km/h on a downhill but on the flat it’s near impossible. Average speed is much better, if I had used 80mm cranks instead of 90mm cranks on my record attempt I wouldve probably gone a km further. Accelerating is also more difficult on shorter cranks, logically.


You are an animal. Those lengths certainly make me less worried about going down to 125s!

Cool. I’ll just get the 125s and ride’em.

Dustin & Tom - are you guys planning to Ride The Lobster in '08?

I don’t understand. I know you know what you’re doing. But first you said short cranks are not faster, and then you said the above.

Tom’s point was that shorter cranks are faster, unless you start getting super-short. Too much of a good thing, and all. I currently have 140s on my Coker, which I put on for the San Francisco tour (steep hills, but paved). They’re great on the hills, but lousy on the flats. I need to put my 125s back on. I’d try shorter ones, but I don’t like going on flat rides. I really need a MUni Coker and a road one.

What he said was that short cranks are faster in top speed too, what I’m saying is:

Short cranks:
Top speed: Slower
Average speed: Faster
Accelerating: Slower

Longer cranks:
Top speed: Faster
Average speed: Lower
Accelerating: Faster

Long cranks:
Top speed: Slower
Average speed: Slower
Accelerating: Faster

My vote is against ever messing with steel cranks.

About a month ago I ordered my first 36 inch uni, a Nimbus 36 with airfoil wheelset, when they first came out in the U.S. Much to my chagrin, the wheelset came with Bicycle Euro steel cranks. (I paid more money to get a wheelset with a lighter rim, so why did UDC include heavy cranks? What sense does that make?) So today, I finally bothered to swap the steel cranks for some aluminum cranks, both 125mm. I was amazed at how much snappier my Nimbus 36 handles. Granted, I still struggled to climb the ~20% grade sections of road on my way up to my new home. Someday I’ll nail them…

My problem is the opposite. I ordered nice aluminum cranks, but my Radial 360 is as heavy as a Mack truck. I have Nimbus 36er envy.

Not sure why you felt the need to grab attitude on this discussion. It isn’t about a Myth, as what I said is true for me. It doesn’t appear to be true for you, which would have seemed to be a simple thing to say in letters of normal size and weight. Also, my comments were under the heading of “Key Learnings”, not “Key Laws of Physics”. They were learnings that applied to me from the riding I did, and they were supported by accurate data, again that applied to me from the riding I did. Perhaps I should have qualified that a bit better, by using the words “I” and “me” instead of “you”.

There may be a point of diminishing (or negative) returns on the shortness vs. top speed issue. You are riding much shorter cranks than I am, and I would imagine at some point (maybe 80mm?) they’re just to short to get much leverage on, so while you can spin smoother, you can’t apply enough muscle power to reach the top speed. That would make sense, but I don’t think that logic applies in the 130mm to 170mm range. Or at least it did not apply with me.