Lightweight carbon wheels

Mccaria

I have been looking for a set of lightweight carbon wheels for the Etape and similar type rides i.e. typically high mountains with long descents.

Given my riding is not race orientated but long day events it seems to make most sense to go clincher rather than tub.

What I need views on is that there seems to be a lot of comments that clincher carbon rims are susceptible to over-heating and punctures/rim distortion on long descents. Given that the whole purpose of lightweight carbon wheels is for their climbing abilities (which in most cases will also require significanct descending) is this too big a product flaw or does the weight advantage make up for the risk of a wheel failure (which would rather ruin the event !)

Anonymous

The clincher carbon wheel issue with overheating comes from those wheels with an aluminium braking surface, there is no surface area to dissipate the heat...

The Lightweight, edge and reynolds clincher rims are all carbon so supposedly alleviate this issue.

redddraggon

NapoleonD wrote:

The clincher carbon wheel issue with overheating comes from those wheels with an aluminium braking surface, there is no surface area to dissipate the heat...

The Lightweight, edge and reynolds clincher rims are all carbon so supposedly alleviate this issue.

I think you'll find 100% CFRP clinchers will suffer from the problem more due to the low thermal conductivity of the resins.

Wheels with alloy braking surfaces tend to be alloy rims with CFRP fairings anyway, so there's little difference with normal alloy clinchers re: heat build up.

Tempestas

Any manufacturer worth considering will have tested their wheels to exceed the limits you put on them.

I read a while back that on longer descents tyre pressure can increase by as much as two bars under braking, this is factored in when stating maximum tyre pressures on wheels. For instance, Lightweight state 116psi/8 bar for their clinchers and are tested up to 12 bar (plus a further 2 bar for heat). http://www.lightweight.info/eng/lr_stan ... tails.html

When spending that sort of money though I would suggest emailing the manufacturer with any queries you may have, they can usually put your mind at rest.

inseine

If light weight is your goal I'm not sure carbon clinchers are the best choice. If there deep rimmed they'll be heavy and if they're not then alloy would be as light. Carbon rims and big decenst are not an ideal combination. Which wheels were you looking at?

Tempestas

inseine wrote:

If light weight is your goal I'm not sure carbon clinchers are the best choice. If there deep rimmed they'll be heavy and if they're not then alloy would be as light. Carbon rims and big decenst are not an ideal combination. Which wheels were you looking at?

Heavy? Are you sure?

http://www.wiggle.co.uk/p/cycle/7/Light ... 360042547/

1095g a pair

I must admit though, carbon does have a unique feel when braking so block choice is important and weather can be an issue. An alloy braking surface adds weight though...so catch 22

inseine

When he said lightweight I didn't realise he meant Lightweight! :oops: The lower case 'L' sent me off track. You really can't be seen grovelling up the last climb on a set of those.

Mccaria

Sorry for any confusion - it was lightweight with a small "l".

Definitely looking for light climbing wheels . Recently been looking at the Xentis squad 2.5 and the DT swiss RRC 570f + 680R combo and also considering buidling a light set with DT Swiss 240 hubs and Edge rims . These wheelsets come out at circa 1200-1300 in weight and are available in clincher form.

What intrgues me about light, shallow rim carbon wheels is that these wheels are clearly designed to minimise weight, which will have most advantage in mountainous territory but seem to carry a high potential downside of puncture or the rim failing on a long descent.

redddraggon

Mccaria wrote:

What intrgues me about light, shallow rim carbon wheels is that these wheels are clearly designed to minimise weight, which will have most advantage in mountainous territory but seem to carry a high potential downside of puncture or the rim failing on a long descent.

The issue is overstated. Get your braking technique correct, and you won't suffer from any issues. It's dragging the brakes that causes the rim to overheat, and there's really no need to drag the brakes.

markos1963

redddraggon wrote:

Mccaria wrote:

What intrgues me about light, shallow rim carbon wheels is that these wheels are clearly designed to minimise weight, which will have most advantage in mountainous territory but seem to carry a high potential downside of puncture or the rim failing on a long descent.

The issue is overstated. Get your braking technique correct, and you won't suffer from any issues. It's dragging the brakes that causes the rim to overheat, and there's really no need to drag the brakes.

Got to agree, whats the point of dragging your carcass up a mountain only to spend the descent braking and worrying.

Pokerface

markos1963 wrote:

Got to agree, whats the point of dragging your carcass up a mountain only to spend the descent braking and worrying.

To prevent death from going over the side of a cliff at high speed.

APIII

Light, shallow rimmed carbon wheels may be fine for going up the hills, but you need to make sure they're stiff enough for descending. You can lose a lot of time going downhill, if you're nervous about the cornering ability of your wheels.

Tempestas

inseine wrote:

When he said lightweight I didn't realise he meant Lightweight! :oops: The lower case 'L' sent me off track. You really can't be seen grovelling up the last climb on a set of those.

My bad too :oops:

Seems I saw 'lightweight' and assumed 'Lightweight'...

Hard to suggest/comment on other wheels without knowing your weight and riding style, and budget of course.

I agree with other posters with regards to shallow carbon rims being ok up hill, but feeling vague and fragile going down the other side. It is a tricky balance...

markos1963

Pokerface wrote:

markos1963 wrote:

Got to agree, whats the point of dragging your carcass up a mountain only to spend the descent braking and worrying.

To prevent death from going over the side of a cliff at high speed.

I was agreeing with Reddragon about dragging your brakes down a hill. I see so many do it on rides and then they come up to me later and ask how I go so fast downhill. Perhaps its 30 years of motorbike riding thats done it but I'm a firm believer of doing my braking all in one go rather than constant feathering.

Mccaria

"Hard to suggest/comment on other wheels without knowing your weight and riding style, and budget of course. "

Weight 180-185lbs
Riding style. Wheels are not for racing but sportives/consistent paced riding and will be used in Alps/Dolomites. Going uphill, concentrate on tempo rather than pushing a big gear and going downhill the priority is to get down safely rather than quickly !
Budget no real limits, but probably wouldn't go above £2k.

Tempestas

That's a nice budget, it's a shame you don't want to go over the £2k price bracket because one of the biggest things I noticed on my Lightweight's was descending, they are balanced and the gyroscopic effect is reduced and the steering feels really precise. I also use Nokon cables, these free up the front end and also improves the steering.

Before the Lightweights I built a pair of FRM hubs onto some medium section carbon rims using CX Ray spokes, these were good but are only really ok for dry weather due to the minimal hub seals. I think FRM hubs have an 85kg rider limit though. These would come in well below your budget and give you a nice choice of rims, maybe a 40mm front and 60mm rear...but make sure you use a good wheel builder

inseine

To be honest you'd do as well on a pair of Dura ace cl24s or similar which come in around 1380g and £550. They are strong, light and reliable. No rider limit as far as i know (you'd struggle on some of the lightest wheels).
I have some Tune hubs with American Classic rims which had Sapim x-ray spokes which failed a couple of times (they were 1250g) Had them rebuilt on other spokes and they're now 1350 but solid as a rock. I'm 58kgs. You'll not notice 100g here or there, but you'll be walking if you break a spoke.

sherer

my friend bought some deep section carbon tubs and they overheated on a descent and caused the tire to go. Not very nice.

Problem is you need to practice on them to work out how to do a 20 min descent and us amateurs might not be the best at that.

Tempestas

inseine wrote:

To be honest you'd do as well on a pair of Dura ace cl24s or similar which come in around 1380g and £550. They are strong, light and reliable. No rider limit as far as i know (you'd struggle on some of the lightest wheels).
I have some Tune hubs with American Classic rims which had Sapim x-ray spokes which failed a couple of times (they were 1250g) Had them rebuilt on other spokes and they're now 1350 but solid as a rock. I'm 58kgs. You'll not notice 100g here or there, but you'll be walking if you break a spoke.

Strange you say that about the CX Rays, I did a lot of research due to my size, I am a 90-95kg track sprinter so wanted a strong spoke, the CX Ray is sold by Sapim as suitable for DH, so was good enough for me to use on the road and crits.

Pulled from Sapim's site:

Usage : RACE, TRIATHLON, MTB, DOWNHILL
Weight : 278g (64 x 260 mm)
Fatigue test / wheel revolutions : 3.500.000
Strength on middle section : 1600N/mm²

Now, if any wheel is built poorly or ridden with uneven tension you will get spoke failure, hence why I mentioned finding a wheel builder who knows what he is doing.

inseine

Now, if any wheel is built poorly or ridden with uneven tension you will get spoke failure, hence why I mentioned finding a wheel builder who knows what he is doing.

Good point and I didn't tell the whole story. The wheels are from xx-lightbikes in Germany and they seem to have a good reputation plus the wheels were superb when they arrived, totally true and evenly tensioned. trouble was that thay were 3 cross on the rear and the spokes were overlapping the heads of ajoining spokes which lead to a kink in the spoke and a weakpoint. I decided to have them rebuilt because this seemed like the source of the problem in my view (I'm no wheel builder) and they are fine now. Probably the spokes were fine. I don't break spokes normally (ever).

Tempestas

Makes more sense now, it's little things like this that a good builder takes into account when spec'ing up a pair of wheels.

inseine

Makes more sense now, it's little things like this that a good builder takes into account when spec'ing up a pair of wheels.

Quite. If i was right with my diagnosis it seemed like a school boy error. Nice wheels otherwise.