Your Bike Rack Might Be Damaging Your Carbon Wheels
TNot long after my friend Gina outfitted her Pivot trail bike with a new set of DT-Swiss carbon wheels, she took it to a bike shop for a tune-up. During the service, the mechanic noticed distortion in the front rim, so she emailed DT-Swiss’s USA office and was told it was most likely caused by exposure to exhaust while transporting her bike on a hitch rack.
That got me thinking. I had noticed something similar happening to my carbon wheels. Twice, after just a 10-minute commute, the rim closest to my car’s exhaust was warped or buckled.
Until now, neither Gina nor I considered our car’s exhaust, specifically the location of it, to be the culprit. And if we didn’t know, it made me wonder how many other cyclists aren’t aware of this potentially dangerous issue. Gone unnoticed, a damaged rim could fail mid-ride and cause a crash. With more riders using hitch racks and carbon wheels, it’s time to raise awareness about this possibly
life-threatening combination. So I did some digging.
I reviewed several owner’s manuals and found nothing related to exhaust. I also contacted wheel and rack brands to find out if they’re aware of the issue, and if so, what steps they take to warn riders. Mark →ordan, a representative for Reynolds, said, “I have not heard any buzz that it’s a common problem for Reynolds.”
And yet some wheel and rack makers do inform users about possible effects of exhaust heat. Enve warns, “Ensure that the rim is well outside of 45 centimetres away in any direction from the exhaust pipe of the car. Similarly, the rim must be out of the direct path of the exhaust, even if it is further than 45cm away.” Russ Fogle, Lead Product Engineer at Rocky Mounts, agrees that it’s a known problem with all bike racks, but says, “Unfortunately for us as rack designers, each model of car has its tailpipe in a different location, pointed in a different direction. If we were to design a rack to avoid one car’s exhaust, that would just move the rack into the path of another car’s exhaust.” And yet, several companies stated it’s more of an issue with trunk racks or hanging a bike over a bakkie tailgate.
But if there’s one common thread, it’s rear-facing exhaust tips. “Rear-facing exhaust tips that line up with the bike rack and lower portion of the rim can do the damage,” said David Agaptio, tech services and warranty manager at DT-Swiss. Fogle suggests adding turn-down tips to redirect heat away from your rack and bike. Another solution is to add a riser or swingaway kit that safely spaces the rack away from the exhaust. My solution? I switched to a rack that positions my bikes higher up and further back. Gina was able to replace her rim at a discount through DT-Swiss’s crash-replacement programme. One new rack and three new wheels later, the lesson wasn’t exactly cheap for either of us. But if our experience can help others avoid the same issue (or even prevent something way worse), then in the end, it’s pretty much priceless.