The rim of my rear wheel broke again, the second time within less than three years. The first time around it was Stan’s XC aluminum rims, the second time it was a rim with reinforced spike holes. The hub (Shimano XTR M9000) is still in perfect condition.
I’m not abusing the rims/bike, I think, but I’m not babying it either. My commute has a some gravel, some cobbles, some paved road, and one set of concrete stairs that I ride. I’d also pull a trailer packed with kids and/or groceries.
Why do I keep breaking rims? Should I opt for carbon rims to get something that is more robust? If so, any recommendations? Perhaps I can get something on the used market as the rear wheel still has a quick release.
When you say commute, is that with a loaded rear rack, and how hard do you pump the tyres up? Just thinking that the stairs loaded, or potholes when loaded for that matter, may not be ideal, and if the tyres are pumped hard perhaps too much of the impacts are transmitting to the wheel?
Stans XC rims are pretty light, and is the second rim similar, other than the eyeleting spoke holes?
Perhaps you need a higher spoke count? Or more of a touring or trail/enduro rim?
I don’t have a rack (yet), just a 40 l backpack. I think the total weight (bike + rider + backpack) is 85–100 kg, depending on how much I cram into the backpack. I am also quite quick as it is entirely flat here.
The Stan’s had fatigue cracks all over the wheel, and the bike shop recommended this sturdier rims to me and laced them to the XTR hubs.
The bike is a carbon XC hardtail, not a city bike. It is very well-specced, the frame is from 2014, but the previous owner tore down the bike in 2018ish and put top-end components on the bike, XTR group set, World Cup suspension fork, etc. I put on XT M8100 brakes and a new stem and carbon bars in 2022 and Rotor 2InPower MTB cranks this year.
The front wheel has had no issues so far. I didn’t think a hardtail would be bothered by stairs.
I’ve seen rims fail in vaguely that way including carbon rims, but they had been used in all conditions, including winter salted roads, which combined with the Alu nipples meant there was galvanic corrosion.
Is it possible you have experienced something similar?
Front wheels rarely give any trouble unless crashed hard - that’s normal. If there’s FS even less chance. You don’t say what the rim is or how many spokes there are, so we have no idea how tough it may or may not be. Regular stairs (= square edged ruts) ridden at speed are going to be hard on the unsuspended rear wheel, and unless you’re super fussed about weight then a 32° (not 32"!) wheel with an Enduro/DH rim and a large volume tyre should hold up way better.
The roads are not heavily salted (unlike where I lived before, my XTR rear mech’s clutch rusted in place), but it is very humid all year around as we next to a lake and there are tons of small lakes and channels crisscrossing the landscape.
I can avoid riding the stairs, but the previous set of wheels failed even without stairs (I took a different route back then).
The first rim failed “everywhere”, the fatigue cracks were all around the entire wheel. I’d have to check where the hole is located, I will update my post later.
Edit: It is a drive-side spoke. And the rim is a Contec Xeta Max, whatever that is.
What tyres, and what pressures? And, was that consistent across the two failures?
As for which rim, as Stephen_Poole suggests, something enduro leaning. But also have it built with good quality butted spokes and brass nipples (better elasticity and less chance of galvanic corrosion, respectively). And if you are running relatively narrow, rock hard tyres, don’t. Go for bigger and a bit softer.
I switched from 2.25” MTB tires (Schwalbe Eacing Ralphs) on the previous wheel to narrower 50 mm gravel tires (Continental Terra Hardpack). I have increased pressures to about 2.0 bar.
The constant is probably the speed, at times I travel at a pretty rapid clip over terrain and cobbles (28–30 km/h when I am by myself and I pack a lot at times (groceries).
It is a pity that I don’t have a thru axle in the rear, because then I’d have an easy time investing in a nicer wheel set.
Commuting, in my experience, can be hard on wheels. I’ve had a few rims fail similarly. I would try a rim with higher spoke count (e.g. 32) and asymmetric rim shape, like a Duke Lucky Star or Stan’s MK4. I use brass nipples to address galvanic corrosion issues on my family’s commuters (baltic sea, lots of salt on winter roads).
I’d start with an offset rim and be careful with the tension. Like a RaceFace ARC or AR. That rim you have looks like 32 hole so that’s not terrible. More spokes is better but you’re looking at a new hub and I don’t think it’s necessary. I’d drop to at least a 2.0/1.8 spoke, if not 1.8/1.5. Have you ever broken a spoke? Use brass nipples, no reason for aluminum.
