[Solved] Tires Deflates During Workout on Trainer

I have an equipment riddle and I’m hoping somebody can help me solve it.

I work out on a Wahoo Kickr Snap, wheel-on trainer. For the first year or so of use it was great, no problems. Lately, however, I have an issue with my rear tire repeatedly deflating within 10-15 minutes of riding. When I’m not working out, the tire maintains pressure indefinitely, but once I get on and start working out, it goes flat and I have to keep getting off and pumping it back up. I’ve tried different tubes and different tire carcasses. With my old road tire, it would blow out after a few minutes on the trainer, now with a trainer tire it’s slower but still failing. I don’t have this problem outside. And I haven’t been able to identify any sharp objects or burs on the trainer contact wheel or the inside of the rim.

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As noted below, the issue was the old, degraded rim tape allowing the tube to press into the spoke holes. After replacing the rim tape, I’m right as rain.

My initial reaction is that you have too much tension on the wheel…try backing off the tension adjustment knob a few turns and see if that helps.

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Tried that last night. Didn’t help.

check your rim strip on your rear wheel, you likely need to replace the rim strip, when the rim strip starts to press into spoke holes your tube can begin to fail.

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HUH? How do you figure that?

With the Snap, the bike is fully supported by the trainer and axle mount. The forces on the tire are purely from the the tension knob setting that applies the compression action between the trainer roller wheel and your bike wheel & tire. Rider weight is irrelevant with respect to the forces on the tire and trainer.

The tangential aspect that might matter here is the potential that you have relatively high FTP in raw watts and train at higher wattage as a result. That can load the tire more because of the higher resistance levels applied to that tire and tube. But none of that is weight related in the pure sense. Actual power is what matters.

Or perhaps you are more talking about the relationship that weight might have if you are using a simulation like Zwift, Rouvy, Fulgaz and the like? In that instance, your weight as input into those apps and the related resistance applied to the trainer may be higher than a lighter weight rider. Hard to say with the limited info you share. But other than that, it is as I covered above.

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^this.

It’s something mechanical.

It has no effect on the trainer, where it’s suspended by steel posts. I’d wager the tension supplied by the trainer ,to the tire/wheel, is lower than when you ride on the road.

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I’ve no idea what its but before binning the the tube if it occurs again line it up with the wheel and it’ll at least give you an idea of where the problem is manifesting. If the hole is too small to see you’ll need to put some air in it first. Generally, a hole on the inside radius of the tube points to a dodgy spoke, on the outside it points to something in the tyre and two holes (a pinch or snake bite) points to the tube being squeezed against the rim when it perhaps didn’t have enough pressure.

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Oh! I had forgotten about the posts!

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Great suggestion about the rim strip!

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Also, are you using a trainer tire or a regular road tire? When I had a Snap I used to blow tubes regularly. Replacing the rim strip greatly reduced the frequency but they stopped once I put on a trainer tire. Just note that you CANNOT ride outside with a trainer tire so if you go back and forth a lot you’ll either need to change tires frequently or get a separate rear wheel.

My guess is heat. I’ve experienced this with inner tubes that I’ve patched after punctures, they’ll run fine outside but never last indoors, something to do with heat buildup toasting the patches I always thought.

Are you running a decent fan by any chance? If you’re a larger rider you’ll be doing a lot of work and making a lot of heat. And if you’ve got a lot fitter over the last 12 months, making big gainzzz :muscle: then you might be surprised how much more heat you make than you used to, might explain why this now and not before. Especially if you’re stretching those sweetspot or threshold intervals into multiple tens of minutes.

Thanks all. The rim strip suggestions had it. That tape was 12 years old and had gone quite brittle as well as pressed into the spoke holes. Put on fresh tape and got through an hourlong workout with no deflation.

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