vvill’s N + 1 Pointless Prize
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N=16 Rockfords Salsa Vaya
3/14/2016
https://www.strava.com/activities/516814994
Yep, another Vaya. Like Gina’s, Kathleen’s Vaya is rigged for commuting/touring with big tires, full fenders, and a very upright position. I’m amazed at how much that upright position impacts reach. This top tube felt short even though it is actually a 54cm. Normally, if set with my preferred saddle to bar drop, I am too stretched out on almost any 54. No such felling here.I also really enjoyed the smooth, clean, grit free drive train. The Viaje’s need (another) good clean after yesterday’s 115 mile gritty rain ride!
Late to the discussion but I just assumed that a skinnier tire was faster because less material was touching the road so less friction. As usual, I know F— All about bikes.
@Subby 136702 wrote:
Late to the discussion but I just assumed that a skinnier tire was faster because less material was touching the road so less friction. As usual, I know F— All about bikes.
This might be over-simplifying, but I think the gist of the argument is that there is the same amount of material touching the road *at the same psi* (i.e. contact patch area is same), but on the wider tire the contact patch is spread out more width wise vs length wise on the skinnier tire (so shape is diffetent). And the former is faster for some reason.
This may be a completely wrong understanding.
Edit: Here’s an article explaining the physics of why a shorter/wider contact patch rolls faster: http://flocycling.blogspot.com/2011/11/flo-cyling-contact-patch-why-wider-is.html
QUOTE=Subby;136702]Late to the discussion but I just assumed that a skinnier tire was faster because less material was touching the road so less friction. As usual, I know F— All about bikes.
That is only part of the equation. And that variable is only true when the road is perfectly flat and the tire is perfectly round. Both physical impossibilities.
The primary thing that causes slightly wider tires to be faster is there is less deflection upwards and sideways of the bike and you when you hit objects. And by deflection I mean vibrations you can feel and by objects I mean 0.25 cm irregularities in the road surface. Of course you must balance out the mass of the tire, the frontal area for air resistance, and the overall surface rolling friction. So an huge tire will end up being slower.
And there are more variables of course, beyond frontal area, the tire shape and tire & rim shape are more important to air resistance. Then there are the the hard to measure variables, such as your fatigue caused by a too small tire increasing vibration. Michelin, Continental, Trek and Specialized have all researched this a lot the last few years, and it is why so many race teams switched to 25s and 28s.
@hozn 136703 wrote:
This might be over-simplifying, but I think the gist of the argument is that there is the same amount of material touching the road *at the same psi* (i.e. contact patch area is same), but on the wider tire the contact patch is spread out more width wise vs length wise on the skinnier tire (so shape is diffetent). And the former is faster for some reason.
This may be a completely wrong understanding.
I was trying to check this out and ended up with a black eye and a bruised cheekbone.
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