Carbon wheels, why would you bother?
- Thread starter Andrew_Culture
- Start date
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will look forward to your review - just looked on the site and very interested in the carbon 29er wheels for disc brakes
@VamP are you getting disc brake specific wheels, if so which ones??
i'm looking at the clinchers for disc brakes and they say MTB tyres max 65psi, but road Tyres 130PSI - so if i put cyclo cross tyres on which PSI would i use?? they are using the same rim, just different hubs
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No I'm getting regular tubs. Two bikes and 4 wheelsets for cantis is quite a barrier to change, plus I don't really need better brakes.
Cyclocross tyres themselves usually have a maximum rating around 50 - 70 psi, so you wouldn't go higher than that, but for off road, you run them a lot lower than that for improved traction. I go as low as 20 psi depending on conditions.
they are going to be for my 29er - i want to run them for road and topwaths - carbons for cyclo tryes and the current alloy rims for big air moutain tyres for when it gets muddy
our towpaths around here aren't tarmc, they are still very rural
Around 40 psi for that usage, drop another 10 for muddy conditions.
i'm running conti mountain king II for the muddy stuff and schwalbe sammy slicks for the hard pack and bike path communting
so was going to put the sammy slicks onto the carbons for the commuting - and the mountain kings onto the alloys for the muddy stuff
does that sound ok??
nice - quoted wheel weights seem a bit off though, but hey ho
not sure what you mean?
its ok ignore me - bad maths day at work
@Pedrosanchezo @Rob3rt @jowwy @Hacienda71
They arrived today. I'll do the whole photo etc thread once I've eked a bit of time, but first impressions:
The finishing is not as flawless as say my Gigantex rims, however, they are absolutely true, and the spoke tension seems even. They weigh in at 1120g, 50g over the claimed average weight.
The ultra extra light ED hubs (256g) look like a quality item, and while I was led to believe that the seals on them were minimal, they actually don't look too bad. In any case if they require a new set of bearings every season, that will be fine with me!
They are now stretching a pair of Dugasts, and inshallah will be glued up in time for National Trophy in Southampton on Sunday.
They arrived today. I'll do the whole photo etc thread once I've eked a bit of time, but first impressions:
The finishing is not as flawless as say my Gigantex rims, however, they are absolutely true, and the spoke tension seems even. They weigh in at 1120g, 50g over the claimed average weight.
The ultra extra light ED hubs (256g) look like a quality item, and while I was led to believe that the seals on them were minimal, they actually don't look too bad. In any case if they require a new set of bearings every season, that will be fine with me!
They are now stretching a pair of Dugasts, and inshallah will be glued up in time for National Trophy in Southampton on Sunday.
Pedrosanchezo
Veteran
- Location
- Perthshire, scotland
Ooooh racing cross with them! Interested to see how they perform. 1120g is still v light.
http://www.training4cyclists.com/how-much-time-does-extra-weight-cost-on-alpe-dhuez/
unscientific but interesting
unscientific but interesting
RecordAceFromNew
Swinging Member
- Location
- West London
Not if you manage to ride the bike up at a constant speed. Compared to riding on a windless day on the flat, the principal difference is that you will be lifting yourself + bike uphill, gaining potential energy (the formula is dead simple - i.e. mass x g x elevation). Of course in reality it is not possible to ride at a constant speed up the 21 bends hence the 1.8L in the tyre should make a difference - It is however imponderable exactly how much difference could theoretically be attributed to the water in the tyres without a lot more data.
However, it is quite easy to evaluate theoretically and fairly accurately how much slower normal additional mass can cause for that or any climb. Let us use his normal bike scenario, assuming no wind, and given he was climbing Alpe d'Huez which is roughly 13km with a total elevation of 1km. Since he made it in 49' 40" in standard trim, and since it takes about 30W to travel 13km on the flat in a windless day over that time, we can evaluate the mass of him plus his bike, because using the potential energy formula above (and energy is power x time), power consumed to combat the vertical elevation alone is 278W-30W or 248W = mass x gravitational constant at 9.8ms-2 x elevation 1000m / time of 2980 seconds it took him. Hence the mass of him and his bike is give or take 75kg, not an unreasonable number huh?
If we add another 1.8kg to his mass like his water bottle, using the same formula and power, it is also easy to find that the new time = mass of 76.8kg x gravitational acceleration at 9.8ms-2 x elevation of 1000m / 248W, or 3035 seconds which is 50 minutes 35 seconds, i.e. 55 seconds slower. Less than his measured difference of 1 minute 54, but a difference is hardly surprising given power meter accuracy is not great, there might be wind etc.
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