I’m racing for the first time on my Hed C2 rims. The recommended pressure is 80-100psi. I train at 80psi. I know with my mountain bike, a 5psi increase makes a world of difference in speed (faster) but reduces traction. Would racing with my Hed C2 rims at 100psi make me faster on the road?
Thanks
Would racing with my Hed C2 rims at 100psi make me faster on the road?
Thanks
I don’t think anyone actually knows the answer to the question above, so I think you’ll have to simply try to test it out for yourself using the best tools you have available and go from there. A power meter, a windless hill and a stopwatch should help.
I can tell you though that on rollers, the C2 rims are no different than any other rims: more pressure=less rolling resistance.
The general trend on the road seems to be that as you increase tire pressure you decrease rolling resistance until you reach a certain point, at which increasing the tire pressure significantly increases rolling resistance - it is better to be on the safe side and lose a little speed then be on the other side and lose a lot of speed. Some people also claim the optimum pressure is where the tire deformation is around 15% IIRC that is why the optimum pressure is different based on rider weight, bike weight, F/R distribution, tire width, etc.
Thanks. It made sense to me that more pressure more than likely means lower rolling resistance, but it’s much less noticeable on the road when compared to MTB.
I am sure that there are some people here that can speak to this much better than I can, but you have to watch out in regards to how increased tire pressure affects speed, and this relates more to the tire than to the wheel. You are 100% correct in that increased tire pressure will make you faster, but it is to a point. As you increase tire pressure beyond a point (by tire) the contact patch between tire and pavement can start to elongate front to rear which will actually give you more resistance. In addition, higher inflation may cause the tire to bounce around more depending on your weight.
All that being said, if the tire inflation range is 80 to 100, I think you’re fine @ 100.
A possible test for this would be to inflate tires to XX, and ride with constant power (erg mode on a CT perhaps) and see what your speed is and do comparisons at different pressures.
I’d be very interested in others views on this as well.
Two questions in line with the OP’s question: a) Do any manufactures publish rolling resistance figures? b) Is the manuf. recommended tire pressure based on optimum rolling resistance or the max that the tire can be safely inflated to?
a) Do any manufactures publish rolling resistance figures?
If they don’t have data, they don’t know how bad it is and the marketing guy can say how great it is - they don’t want to know.
b) Is the manuf. recommended tire pressure based on optimum rolling resistance or the max that the tire can be safely inflated to?
should be based on optimum rolling resistance, the max pressure will most likely not get you very good rolling resistance, unless you are on a wooden velodrome or something.
Thanks. It made sense to me that more pressure more than likely means lower rolling resistance, but it’s much less noticeable on the road when compared to MTB.
Well, one of the reasons I suggest using whatever tools are available to test this out is that the butt dyno isn’t always that well-calibrated.
For instance, here’s one guy’s take on MTB and rolling resistance:
http://www.schwalbetires.com/wider_faster_page
There’s no doubt that 20psi can feel slower, but his results seem to suggest something else, even on a relatively smooth surface.