Hey all. I’m lucky enough to be spending 2 weeks in France/Spain cycling in the Pyrenees next month. I’m going in a tour group, which I think will make it even better. Reading through the information the tour operator has sent me, one thing stood out. They are recommending that I leave my carbon wheels (I have Bontrager Aeolus 5) at home due to the risk of delaminating under heat from rim braking. I do have a pair of aluminum wheels (Bontrager RXL) that I upgraded from. Oddly, both wheelsets weigh exactly the same (1440grams). But I just love my carbon wheels, you know? Do you think the risk of carbon wheels delaminating is real or are they just being risk averse? Should I just take the aluminum wheels even though my bike doesn’t look as cool? Or ignore the advice and have the best gear possible for the trip of a lifetime?
Those are mid depth? Have you spent much time with the wheels in the mountains? In crosswinds?
My front is 54 deep and descending at +35mph in strong crosswinds becomes a heavy breaking experience (disc brakes).
Yep, the Aeolus 5 are 50mm. I’ve ridden then exclusively for the past 2-3 years (probably 25,000 miles) in all conditions. I’ve never been bothered with them in the wind. Not much riding in the mountains though.
Sorry to raise another issue, but something else to consider. I never had a problem descending 40-50mph in crosswinds on stock Bontrager box rims, but the first fast descent in strong crosswinds on my ENVE 5.6 wheels saw a lot of breaking (and those are some of the best at dealing with crosswinds). With my disc brakes I’d definitely go 30ish depth if I was doing a lot of mountain riding in NorCal. The steep descents tend to have a lot of wind in the summer.
Thanks for raising it. I was more focussed on ruining my carbon rims than crashing 
Sounds like for going for the shallow alloys is the way to go. Thanks.
I tend to believe that experienced riders logging a lot of time in the mountains would get used to the “above 35mph twitchiness” on my wheels, but I don’t pay enough attention to wheel depth on mountain stages of Giro / leTour / Vuelta to be sure.
Pretty sure the pros use a rim depth in the 30’s for the high mountain stages
Did a ~45mph descent without wind recently, they are fine in those conditions.
I have ridden in the Alps on carbon rims and they got hotter sitting outside the coffee stop than under braking. But you might have heavy rain in the mountains at any time so how do your carbon rims work under braking in the wet? Mine were terrifying.
Love the Pyrenees but they are right. More for the fact that it almost certainly will rain, and having descended Aubisque in the rain on carbon rims I would not recommend!
Take the box rims, they don’t look as cool, but you will worry less the whole two weeks and get to enjoy literally the best cycling I have done anywhere in the world.
I would follow their advice.
Don’t look at Pro’s, they have near unlimited wheelsets ,top mechanics who inspect them and certainly dont use them for as many miles as we do.
Looking a bit faster isn’t worth it if the wheel fails on you, nor if it’s wet and you run into someone or miss a corner.
Your life and health is worth more than good looks and a few seconds gained
I am going to Stelvio end of this month have exactly the same wheels(Bontrager). I will leave them at home while I will be riding with my good old alloys.
Have an epic trip!
One point thats not been raised is the factor of getting replacement spokes in the event of a breakage. I take box standard small flange hubs with box section alloy rims, where I can get a replacement spoke from the LBS. A friend of mine took a pair of Ksyrium wheels away and couldnt get a spoke after one broke, ruined any of his planned rides. Taking good tyres and tubes will make riding as pleasurable as needs be without being paranoid over rim depth.
Take the alloy.
There may be riders in your group that aren’t very confident. You may end up dragging your brakes more than you think.
Crosswinds on a downhill are a possibility and could catch you out.
It would suck to ruin your trip if you mess up your rims. It is unlikely but far more unlikely than with alloy.
Same weight? Want to bring the carbon because the look cool? Just take the alloy. It’ll be a lot cooler to spend your vacation confidently braking with less concern.
+1 for @DingleTower comment. I rode the French and Italian Alps last year and went through the same debate. Took my alloys in the end and didn’t regret it. When it rains in the Alps it rains hard and you cannot always descend the way you normally would - wet roads, slow riders in your group, or traffic holding you up could all conspire to you dragging your brakes more than you would like. And when the opportunity arises and you want to loosen the reigns on a fabulous decent, the last thing you want to worry about is your rim condition!
Alloy !
Long descents on unfamiliar roads, possibility of wet descents, cross winds, etc… go alloy! Without a doubt, you will get better braking regardless of the conditions with the alloy rims.
How was the trip?
too late – but I would have said rent some good alloy tubulars when you get there.
no clinchers on real-deal descents.
Well, it didn’t quite go according to plan unfortunately. It was a 14 day group tour that included my mother. She had a nasty crash descending the Rocacorba on I think day 3 and I spent the rest of the trip in the hospital caring for her. She’ll be ok, but it was seriously scary and will take many weeks to recover physically and a lot longer mentally for her. It was a great experience for the short time I was actually riding and I wish I could have completed the trip.
It’s a shame really since there was a lot of climbing ahead on the tour and while I screwed up the pacing, I did hit some PR’s on the Rocacorba climb. 312 watts for 40 mins 
You can see from the climbing portion that I went out too hot on the first half and couldn’t keep it up on the second half. It was a really hot and humid day as well, so I’m really happy with the effort. KOM owner James Knox is a full 10 mins faster than me which is just amazing and shows the cavernous gap to the pros.