4

Why are they used only in the back if there is no risk of winds at all?

  • What happens when the wheel turns sideways? – Daniel R Hicks Jul 1 at 23:13
5

Because it's not permitted under UCI regulations.

Rule 1.3.018 applies, which includes this section:

In track competition, including motor-pacing, the use of a front disc wheel is only permitted in the specialities against the clock.

Disc wheels are commonly used in the sprint qualifying round (i.e. the flying 200 metre TT).

  • 1
    The follow-up question would then be: Why do UCI regulations allow rear disc wheels, but not front disc wheels? – cmaster Jul 2 at 6:52
  • 5
    I can't answer for the UCI technical commission but if I had to guess it's because the handling characteristics of a front disc wheel makes them less suitable for rapid response to steering input, a trait desirable in mass start and match racing (IOW it's a safety consideration). Using a disc on the rear doesn't affect steering response. The difference (slowness) in steering response of a front disc was my experience when using them on the track. Apart from individual timed events I used them during team pursuits. – alexsimmons Jul 2 at 8:04
  • 2
    As to there being no wind, while that's true in an absolute sense, it doesn't mean a bike and rider experiences zero yaw at the track. You experience wind yaw when in the turns, and when entering a turn a rider experiences a change in yaw angle which also contributes to handling issues with a front disc. On average the yaw experienced on the track is a few degrees. Timed events are ridden under controlled and predictable conditions with inherently less risk than match and mass start races. – alexsimmons Jul 2 at 8:11
  • I would add to the answer what you wrote in the comment to set it as resolved, as cmaster commented I wanted to know the reason behind. Thank you @alexsimmons – nck Jul 20 at 10:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.