Originally Posted by
Robert A
Thank you for both posts. What's the rationale for lighter riders avoiding wider tires? Too much air volume per pound of weight?
Since you have ridden Shamals, do you think the narrower rim (17c) makes it any less desirable than the wider alloy competition (HED/Ardennies, Easton/EA90, etc.) which run closer to 18c-20c?
In a way, your question about wider tyres (i.e. tyres with a bigger air volume) is framed from slightly the wrong direction - the real argument is about tyre pressures and whether lower pressures are desirable, which wider tyres facilitate under certain circumstances.
Part of the problem that has long been around is that a good many consumers (and plenty of mechanics, too) see the max pressure on the sidewall as a target, not a maximum. Lighter riders should always have run lower pressures (professional race mechanics have known this for donkey's years) as one way to consider a pneumatic tyre is as part of a suspension system - providing a significant part of the "rebound" element. The rider forms a significant part of the damping element. The more rebound you have (the higher the tyre pressure, amongst other things), the harder the damping (you) has to work.
A bigger air pocket allows a lower pressure with a reduced likelihood of pinch punctures / damage to the rim sidewall - but a lighter rider rider compresses the tyre sidewall less, so in my opinion, tyre size could and should be proportional to rider weight.
Rim width can to some extent dicatate tyre profile - the 23, 25, 28c description is slightly misleading in that it is an experession of the size of the tyre casing itself - the actual profile the tyre adopts can be dictated by several other factors, though, the lay up of the case, the type and thickness of the tread etc ...and the width of the rim. A wider rim tends to produce a less "balloon-shaped" tyre as the bottom edges are not so crimped in by the width of the rim. Wider rims, C19s and C21s can't always mount a 25c tyre in safety, according to the current ETRTO specification, so the user has to factor rim width in against minimum safe tyre width, alongside of brake clearance ...
Because I haven't been all that seduced by the "wider is better philosophy" of tyres (being reasonably light for my height - 6 foot and 154 lbs at the moment, more like 148 when "properly" in shape), I don't find the C17 any kind of handicap. I run Shamal Mille Two-Way-Fit (2WF), with a 23c on the front, a nominal 24c on the back, with tubes - and find the comfort, speed and handling completely to my satisfaction. I tried a set of Hed Ardennes and couldn't, even with my "Grade 1 rose-tinted specs" on, find anything in them I liked better than the Shamals (or for that matter, the Bora WTOs).
NB Not all the Campag C17 rims can be run with 23s though they can all be run with 25s.
Zonda C17s are 25c minimum, Sciroccos, Khamsins and Calimas likewise. Shamal non 2WF have not been tested with 23cs, nor have Bora 35s or 50s in either version. Bora WTOs have in all versions and they're fine (they are also tubeless ready).
It's maybe worth saying that rims with a solid floor (ie not drilled for access to the spokes, so needing some type of introducer - in Campag's case, a magnetic implant that is used to place the nipples ) and a wider profile tend to be torsionally stiffer than their fully drilled betherin - so if ultimate torque transfer is what you are after, wheels with a rim of this configuration could be ideal. A wider rim is generally torsionally stiffer than a narrower rim of equivalent depth because the cross-sectional area is greater and rigity in a tube is a function of the square of the cross-sectional area.