Jim’s Tech Talk
By Jim Langley
The question that we’re tackling today is related to our article last week which included tips from the rack company Küat.
Another Important Bike Rack Use Tip
Reader Ken Stevens asked:
“What about the issue of hot car exhaust damaging carbon fiber rims as per wheel company instructions such as on my Zipps: Do not expose Zipp wheels or rims to hot vehicle exhaust or allow the rims to contact any vehicle exhaust components.”
Our Reply
Thanks a lot for raising this costly mistake Ken and sharing what Zipp said. It’s just as dangerous for tires and the tubes inside as it is for carbon components.
How hot are tailpipes and exhaust?
According to JD Power online, “Typically, the car exhaust pipe(s) reach a temperature of 400-500 degrees Fahrenheit. But some performance vehicles might have temperatures in the range of 800-1,000 degrees Fahrenheit.”
Even more dangerous for your bike is the exhaust gas, which can be hotter still than the tailpipe, up to 1,200 degrees °F or more depending on the engine, according to other experts.
If you’re interested in a demonstration, I found this video informative:
When do rubber (tires) and carbon (rims, components) start to become damaged?
Searching for a range of temperatures to give you, it was obvious that the answer to this question is much simpler. Because, even the low end of the exhaust system and exhaust gas temperature range, is plenty hot enough to ruin your carbon wheels, frames and tires. The resin inside carbon components begins to degrade at 212 degrees °F, while tires could soften at 356 degrees and tire casings (sidewalls) at lower temps. Here’s a resource to learn more about rubber products: https://rubberandseal.com/at-what-temperature-does-rubber-melt/.
So what should you do?
The key thing is to be sure that the bikes and all parts of the bike are never touching any part of the exhaust system and they should absolutely never be low enough to be in the direct path of the exhaust gas exiting the tailpipe(s).
Hitch racks are attached to the hitch. I would think that the engineers design hitch racks to hold the bikes well above the tailpipe. But, it’s possible that the hitch on a vehicle might have been added on after the car was sold and it’s not in the usual spot, so it’s always up to you to check and be sure the bikes are up and out of harm’s way. With some hitches you might need to raise the rack with an adapter.
The Riskiest Racks
In my experience looking at bike carrying vehicles while criss crossing the USA many times in our RV, and while attending loads of bike events, the racks that are more problematic are strap-on trunk/hatch style racks. These have to be adjusted to avoid the tailpipes and the strap adjustments, if not correctly connected, can slip letting the rack drop lower from the weight of the bikes.
Even if the straps are adjusted properly and the straps hold and don’t slip, another common issue I see is that people don’t understand how to mount bikes to these racks. Maybe the rack didn’t come with directions? I’ve seen bikes hung with the wheels and tires directly behind the tailpipe.
If the bikes are not on the rack as intended by the rack designer, the bike or tires may end up next to the exhaust which will likely result in serious and expensive damage when they get where they’re going. So with these types of racks you want to pay attention and use care when mounting the rack and the bikes to it. Plus, you should stop on longer trips to check the rack and make sure it and the bikes are staying put.
Please share your experience
It would be interesting to hear about damage to bikes from the exhaust system. I’ve seen melted and burned tires and a carbon rim. I can’t recall ever seeing a damaged carbon frame from this mistake, but I bet it’s happened. I hope this reply to Ken’s great question ensures you always keep your bikes safe.
Lastly, here are some excellent rack use tips from a reader
How To Safely Transport Bikes on RV Racks
For years, I’ve used bike racks and covers on both Class C and Class A RVs, logging well over 100,000 miles in diverse weather conditions and on all types of roads without issues. My success stems from a reliable method for securing bikes and protecting them with covers. Below is my approach to ensure safe and damage-free bike transport.
1. Secure the Bikes Effectively
A high-quality, well-engineered, heavy-duty bike rack is essential for safe transport. However, don’t rely solely on the rack’s built-in attachment points. To ensure maximum stability, I use the following techniques:
• Ratchet Straps for Extra Security: In addition to the rack’s attachment points, I use ratchet straps to firmly secure the bikes to the rack and RV.
• Toe Straps for Wheel Stability: I secure the bottom of each bike wheel to the rack’s wheel tray using toe straps. This prevents vertical movement and keeps the bikes steady, even on bumpy roads.
• Regular Inspections: Before each trip, check all straps and attachment points for wear and ensure they’re tightly fastened.
This combination results in a rock-solid attachment, minimizing movement and reducing the risk of damage to both the bikes and the RV.
2. Protect Your Bikes with Proper Covering
Covering your bikes is critical, especially for high-value models or those with sensitive electronics. Exposure to road debris, rain, and UV rays can cause significant damage.
2.1 Shield Sensitive Components
For bikes with electronics (e.g., e-bikes with displays or battery packs), I use kitchen plastic wrap, such as Press’n Seal, to tightly cover any components that cannot be removed during transport. This creates a water resistant barrier against moisture and dust.
2.2 Use High-Quality Bike Covers
Invest in a high-quality, weather-resistant bike cover that fully encloses each bike. If a single cover isn’t large enough, use two covers: one placed under the wheels facing up and another over the top facing down. Secure the covers together assuring the top cover overlaps the bottom. Use bungee cords or straps to ensure a snug fit that won’t slip down during transit.
2.3 Prevent Billowing with Netting
To eliminate drag, noise, and wear from loose covers, I use cargo netting (commonly used for pickup truck beds) to hold the covers tightly against the bikes and rack. This is key. The netting prevents billowing, reduces wind resistance, and minimizes abrasion that could damage the bike or cover. Ensure the netting is taut and securely fastened to the rack.
These tips were kindly provided by a reader who signed his comment as “Bill W.” Thanks a lot for taking the time to share your expertise with everyone Bill, appreciate it!
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
Racks can be convenient, however I prefer to transport my bikes inside for security and protection from the elements and road debris. I never had an RV, but we used to have a camper van and I arranged it so the bikes would stay inside even while slept.
When we had a boat we occasionally took our bikes with us when we would sail to Santa Barbara. Safely securing our bikes in the V berth of a sailboat was a good trick.
I currently have a pickup trick and our bikes ride inside a camper shell. We don’t sleep in this truck so there’s never a conflict.
I use old tubes to secure bikes and covers to racks and for many other tie-down requirements. Yes, it is the less expensive and visually challenging option but it is effective.
great way to recycle!
I use a Kuat rack on my EV. No exhaust=no problem.
I found a great solution. I bought an EV!
I have had 4 bikes on my Honda Crosstour, internal combustion engine, 2 on bike, higher than exhaust and two up top. Handle RAGBRAI fine.
A long time ago I read that if bike wheels/tires are near the exhaust pipe, you should wrap the part of the tire/wheel near the exhaust pipe with aluminium foil.
My friend’s rear-hitch bike rack on his station wagon is designed for a taller suv, so their bikes site quite low relative to the car bumper and I suggested this to them.
See an auto parts store for an exhaust tip that lets you aim the exhaust a different direction. Low cost, effective, easy.
With reference to securing,at every stop, nature break, gas, food, etc. check each bike that it is still secured. Things happen on the road.
Thanks for the tips everyone, good stuff!
Jim
Jim,
I have a 1UPusa bike rack. One of the main reasons that I purchased this brand, is because of how well built it is. All metal and no plastic. Bike is secured well. 1UPusa sell direct. You can go from one bike to four on the trailer hitch style carrier. I do not have bike cover, but would look into one for traveling a longer distance.