cbr shadow wrote:
I went out on my regular group ride this past weekend and couldn’t keep up with the group on descents when there was a strong crosswind. The crosswinds were catching my Roval SL45 wheels and making me wobble all over the place. I like these deeper wheels for other conditions, but the crosswinds are making me use my brakes when others don’t have to.
I’m considering something like FLO 30 in the front, FLO 45 in the rear. I know it’s common on TT bikes, but I haven’t seen a smaller aero wheel in front on road bikes before – is there a reason this is less common on road bikes? My understanding is that the front wheel is what is mostly affected by the crosswinds.
Would this be a decent upgrade from the Roval SL45’s?
This is for a Specialized Venge.
A few thoughts on crosswind stability for you.
1. Front wheels cause more stability problems than rear wheels because they have a steering axis (your handlebars/head tube). When wind hits your front wheel it can cause the front wheel to turn, which can cause stability issues, and for lack of better terms, scare you. The depth of your front wheel, and the shape of your front wheel both contribute to the instability. In most cases, the deeper the wheel, the more unstable it becomes. With respect to wheel shape, wheels that produce a high amount of yaw torque (a fancy way of saying the wind causes your handlebars to turn) are also less stable. Some of the most modern wheel designs have taken not only aerodynamics into consideration, but also yaw torque. As an example, our design algorithm included yaw torque as a parameter. This is because we know stability is important, simply because a fast wheel that is nearly impossible to ride, will slow you down because you can't control it.
2. The depth ratio of your front wheel compared to your rear wheel matters when talking about stability. As your rear wheels gets deeper with respect to the front wheel, your center of pressure moves towards the rear 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 create more rear area with a deeper rear wheel, the center of that area moves backwards. As your center of pressure moves backwards, you reduce the force on your front wheel, and in turn increase stability.
For you, I think a 30/45 would be a good combination. If you are having a hard time controlling a 45mm front wheel, your next best bet would be a 30mm front wheel. Pairing that with a deeper rear 45 also helps improve your stability. The only thing to remember is that the front FLO 30 is an all aluminum wheel, and the rear FLO 45 is an all carbon wheel. You can ride these as a pair, just make sure you get the brake pads right.
If you have any additional questions please let me know.
Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling