|Fewer spokes make pedalling noticeably easier in a peleton?||Scy|
Jun 9, 2002 8:56 AM
|I'm looking for a new set of wheels and am trying to decide between light wheels (<1600 grams) and low-spoke count wheels (~1800 grams). |
I ride near the middle in a pack of at least a hundred riders. In this situation, I believe the aerodynamics of the wheels with respect to air resistance from the front is not that important (I realize this issue is disputed). I am not interested in aero rims.
However, I haven't heard much disucssion about the effect of the spoke count on rotational air resistance. With all other things being equal (rim profile, spoke gauge, spoke profile), how much difference would, for example, a 20-spoke wheel make compared with a 28-spoke wheel. Have there been any objective studies done on this.
Also, on this board I once read that paired spoke designs such as the Shimanos and Rolfs actually create more air resistance. Any truth to this?
Jun 9, 2002 3:50 PM
|Going from a 36 to a 24 might be worth 0.2-0.3 mph (0.3-0.5 kph) out in the open. 28 to 20 might be worth 1/2-2/3 of that. Those numbers assume that you are already in a good aero position. In a group, you are most likely not in a good aero position, but then you don't need to be. Who you are sitting behind will have a LOT more effect than taking out some spokes. If you are riding in a crit, where you are constantly braking for turns, then light weight trumps aero, especially in the wheel (rim/tires) department. If you are climbing, then weight is weight whether it is in your wheels or your water bottle. And, a light wheel that saves it's weight in the hubs is no better than shaving the same weight somewhere else, even in a crit.
Regards paired spoking, I believe the wind tunnel tests showed that the paired spoke wheels have nothing to offer over conventional wheels with similar spoke counts. Recognize, however, that there are many brands and models of wheels showing that they are the fastest in the wind tunnel. They can't all be fastest, so this suggests that perhaps there are ways to tweak the test/data to make your design look better. There is no standard protocol for bike wind tunnel testing, so it is hard to compare results/claims.
Jun 10, 2002 8:12 AM
|As Kerry suggests, I'd bet that any difference would not be measureable, and would be dwarfed by other factors. The spokes might matter when fully exposed to the wind, but I doubt they have any effect when drafting mid-pack.
On a scale of 1-100 of things to be concerned about in racing, with 100 being fitness, 75 being body weight, etc., I'd say spoke count is about a 2.