Velodrome bike specifications
 

Hello, new to track cycling. Looking at buying a track bike but have a question on bike specifications.

My local velodrome (derby UK with 42degree bank) has a rule stipulating minimum bottom bracket height if 280mm (floor to centre of bottom bracket) and 165mm crank arm lengths, but also in brackets (170mm).

A couple of people have said the cranks must be 165mm or I risk coming off! I.e. the pedal will hit the banking.

I’ve read online that some riders use 170mm so I’m querying why the people I’ve spoken to insist on 165mm (?) they say 170mm is only suitable for riding the black line (pursuit) but I’d argue that the bottom of the bank is the same angle as the top of the bank so why would this matter?

My understanding is that 165mm is preferred because of higher possible RPMs and not to do with the pedal hitting the bank or can you hit the bank with 170mm crank arms? Reason I ask because I’ve seen a lot of track bikes for sale with 170mm but obviously I wouldn’t want to buy one if it’s not suitable.

I just went to their website. If you are new, I would suggest renting their bikes and riding a few times. That would be the best way to get your questions answered.

First, I agree with Scott - rent bikes and ride it a few times.

As you noted, I think the biggest reason for shorter cranks and higher BBs is saftety - to reduce the chances of a pedal strike, which are likely to cause your rear tire to lift and then you slide off the track. (Some will argue it's about RPMs.)

That said, I ride 170s. I have long legs, and my fitter thinks it fits me better. My bike also has a fairly low BB for track bikes though I think it complies with the track mimiums. My home track is also 42 degree banking.

I have clipped a pedal solidly and slipped once. I have rubbed my pedal many, many times. In fact, my straps have clear wear on them from scraping the concrete track. It does take some finesse and awareness to run 170s on my home track.

If you are new, it is probably a better idea to run shorter cranks. If you read through this forum enough, you'll find that most people change track frames pretty frequently in their first few years of riding and racing, as you learn more about what you want and dial things in.

Measuring the clearance between the outermost pedal point of given bike and the floor is the easiest way to compare different bike settings from this perspective.

However, except crank length and BB drop, Q-factor, tyre width/height and low enough speed are additional factors that affect hitting the bank. Two real bikes I ride might be compared.

(1) 291 mm BB height produced by 47 mm BB drop + 22 mm tyre; 172.5 cranks; and ~65-66 mm Q-Factor on the right (Miche Primato, supposedly symmetrical).

(2) 277-278 mm BB height where drop is 60 and tyre is 21 mm; 167.5 cranks; and ~68 Q-F right (Miche Team, asymmetrical, to accept large chainrings on this certain frame, indeed). Some triangle calculations by using the Omnicalculator should prove that hittig the bank at the same angle/speed is more likely in this case, at least in theory.