My original post, about my wheel failing during tire installation, was taken down for not being a 'repair question.' Since there were 50+ comments worth of mechanic advice in that thread, I’m archiving the 'illegal' knowledge here. After cracking the rim while using Crankbros Speedier on a tight bead (Maxxis Rambler), I posted a 'lil sob warning over to r/bikewrench which got taken down for not being a question, so I thought I'd at least have ChatGPT summarize their community's feedback here in hopes this is a friendly reminder to just keep working the elbow grease and not grabbing tools when things get hard…
- Directional Stress & Carbon Design: Carbon rims are engineered for specific stress tolerances in specific directions. Using an installation tool to 'pull' a bead on can apply force in a direction outside these design parameters, essentially acting like a chisel on the rim wall.
- The ETRTO Tolerance Trap: Rim/tire combinations can be a nightmare if the rim is at the upper end of the ETRTO size tolerance and the tire is at the lower end. In these cases, even plastic tools can exert enough leverage to cause a failure.
- Bead Holder Warning: Experienced mechanics advised against using bead holders on carbon rims entirely. They take up valuable space in the center channel, actually making the installation harder and increasing the risk of damage.
- The 'Never Lever' Installation Creed: Even with 'install-friendly' tools, the pros recommend finishing the mount at the valve stem to ensure maximum slack. If it’s too tight for thumbs, use padded cycling gloves or talcum powder for grip rather than mechanical leverage.
- Alternative Tools: For those who must use a mechanical aid, the Kool Stop Tire Bead Jack was recommended as a safer alternative that wouldn't have this specific directional loading issue.
Anyway, hope this summary of the other thread can live on and be of use to someone else in the future before you make the same fateful mistake.
Original title and description was: Warning for the Crankbros Speedier levers for tight beads…
Or maybe it’s a story of something else. Feel free to roast me. Not the way I wanted to start my morning.
by Krazykev300
5 Comments
Thanks for the post. Sharing the hidden oops when dealing with carbon fiber can be a bank account saver for us all.
Use no tools for this. I sometimes use a tire lever to start the removal… but this is 95% tool free.
That seems stupid. It’s very much /bikewrench territory.
***Perhaps it’s like Jeapdordy. You didn’t put it in the form of a question.***
“So I just reamed my carbon rims with those crankbros levers, Alex. Can someone answer my question, is this related to the ERTO Tolerance trap, and has anyone had good experience with the **Kool Stop Tire Bead Jack**?”
“And why do Experienced mechanics advise against using bead holders on carbon rims entirely, Alex?”
https://preview.redd.it/7hnazh2v8mfg1.png?width=1500&format=png&auto=webp&s=5b409b90f1bbf025120c6674dae437be1a2825d0
thanks for your feedback.
i use 2 tire irons simultaneously on carbon clinchers to avoid that exact issue to remove the tube; then i pinch the tire beads together with 2 small vise-grips about 3cm apart and push that part into the wheel channel opposite the valve hole, the tire usually goes into the rim with minimal faffing
TBF, r/bikewrench are fascists; they seem to be looking for any excuse to bong posts.