robegan99 wrote:
Canadian wrote:
ironslave wrote:
Do any of you put a wheelset on like that? Say a zipp 808 in the front wheel and a 404 on the rear wheel? What is the advantages or disadvantages of doing this?
Thanks Your biggest disadvantage would be stability. Here's an explanation.
1. Your front wheel connects to a steering axis—your fork and handlebars—and as a result, is affected more by crosswind than your rear wheel. Crosswind not only pushes your front wheel side to side, but it can also turn your wheel left to right just like your handlebars do. You feel the effects of crosswind more intensely the deeper your wheel gets. Having the wind turn your wheel while descending in the aero bars at 40mph is an unsettling experience. Riders in this predicament often sit up on their hoods to control their bike. Doing so, takes their body from an aerodynamic position and puts it directly in the wind. Your body is the biggest source of drag on your bike. If you are sitting up on your hoods to control your bike, you are losing time.
2. The depth ratio of your front wheel compared to your rear wheel matters when talking about stability. As your rear wheel gets deeper in comparison to the front wheel, your center of pressure moves towards the back end of the bike. To visualize this, imagine you were looking at a picture of yourself riding your bike from the side. If you had to find the center of the "area" you create, that would be your center of pressure. As you increase rear surface area with a deeper rear wheel, the center of that area moves backward. As your center of pressure moves backward, you reduce the force on your front wheel, and in turn increase stability. I like this explanation. But is there a tipping point to where putting the center of pressure too far backwards becomes a disadvantage? If not, why isn't everyone running super shallow front wheels, with discs in the rear?
I can't really see a case were too much rear pressure is a bad thing. I think the point of no return is going too shallow on your front wheel and losing time as a result.
For example, most people can confidently control a 60mm wheel in most wind conditions. Being overly cautious and using a slower front FLO 30, when it's not required to maintain control of your bike, would be crossing the point of no return.
Does that make sense?
Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling