Crashed... Dented my rim... Safe?
08-24-14, 08:29 PM
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Crashed... Dented my rim... Safe?
I just moved to Boulder Colorado and decided to go on a night ride... Long story short, I hit a curb that I thought was a ramp because I have depth perception issues at night... I was going between 20 and 25mph and I hit the curb pretty much head on. My bike is fine except I threw my rear wheel out of true, tore my new GP4000S that I had on the front (around 300 miles on it), and dented the braking surface of the rim. When I brought my bike into my dorm I inspected the front wheel and I could see stress crazing around the dent.. My wheels are Mavic cosmos (eyeleted spoke holes, double wall alloy rims that closely resemble mavic open sports).. I work in a bike shop so I brought my rear wheel to work and trued it in the truing stand there. When I got home from work I took an old cone wrench and hammer and banged out the dent from the inside surface of the rim (where the rim tape is) and got it fairly flat. The stress crazing seems a little worse than it did before I banged it out...
Here are my two concerns: if I put on a new tire and inflate it to 100psi, is the hook likely to catastrophically fail? (ie will the rim explode?) And if the rim can hold the pressure, can it hold my weight?
Fwiw I'm prepared to replace the wheel/rim but I'd like to avoid it if at all possible
Here are my two concerns: if I put on a new tire and inflate it to 100psi, is the hook likely to catastrophically fail? (ie will the rim explode?) And if the rim can hold the pressure, can it hold my weight?
Fwiw I'm prepared to replace the wheel/rim but I'd like to avoid it if at all possible
Last edited by AlphaDogg; 08-24-14 at 08:34 PM.
08-24-14, 08:36 PM
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99% of the time the answer is yes. Of course it's always a matter of degree, and the specific alloy used, but the odds favor you if you don't see any visible cracking. The rim shouldn't split from air pressure because the damage is limited to a very small zone, and there's plenty of support to either side. Likewise it shouldn't collapse from your weight because spoke tension/rim compression is much more than that.
The acid test, especially in a front wheel is how the braking is. Minor pulsing is OK and will probably resolve with time, but any serious pulsing in a front brake can cause modulation issues and a sudden grab or lockup in an emergency stop. So that's the 1%. If the braking modulation isn't good enough for you to feel it's reliable and predictable, rebuild the front. BTW- equally grabby brakes in back aren't as serious a safety issue.
The acid test, especially in a front wheel is how the braking is. Minor pulsing is OK and will probably resolve with time, but any serious pulsing in a front brake can cause modulation issues and a sudden grab or lockup in an emergency stop. So that's the 1%. If the braking modulation isn't good enough for you to feel it's reliable and predictable, rebuild the front. BTW- equally grabby brakes in back aren't as serious a safety issue.
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WARNING, I'm from New York. Thin skinned people should maintain safe distance.
08-24-14, 09:05 PM
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Anyone know an eyeleted 24h rim that matches the 605ish mm erd of the mavic cosmos?
08-24-14, 09:37 PM
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aren't you jumping the ***?
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08-24-14, 10:42 PM
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08-24-14, 11:24 PM
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You're jumping the hand-carried projectile-throwing device.
You can always buy another Mavic. Maybe a Cosmos, even? It is silly, but I am anal about having my rims match.
You can always buy another Mavic. Maybe a Cosmos, even? It is silly, but I am anal about having my rims match.
08-25-14, 12:15 AM
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Mavic discontinued Cosmos rims at least 8 years ago. The cosmos is basically the same as the Open Pro (605mm erd vs 603mm erd, same profile, same double eyelets).... I'd lace it up with an open pro if Open Pros came in 24h varieties... The Cosmos is basically an Open Pro that came in 24h/28h varieties. The Open Pro only comes in 28/32/36h.
08-25-14, 08:28 AM
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08-25-14, 06:39 PM
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Went and got a new GP4000S2 and threw it on the rim. Trued up the wheel and inflated the tire to 110psi. It's been holding pressure with no signs of impending doom for the past 2 hours. I'll ride it and test the brakes tomorrow
08-25-14, 07:17 PM
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Big Picture question - why are you riding 20-25mph at night if you have depth perception issues at night/
08-30-14, 11:43 PM
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My garmin says I lied. I hit the curb at about 13mph and rapidly decelerated to 0mph
08-31-14, 06:49 AM
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You didn't lie that speed exageration is the average % of inflation for any speed described on the internet forums.
08-31-14, 11:58 AM
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It may be possible to hunt down a cosmos rim, I'm sure there are one or two shops in boulder 
My Cosmic rear exploded when I backed into a car at 40km/h. I was able to get a replacement at my LBS, but that was 6 years ago. It's a pain, and more costly due to the fact that it's a special drilling compared to a regular CXP33 rim, just as your's is a special drilling of an open pro.
My Cosmic rear exploded when I backed into a car at 40km/h. I was able to get a replacement at my LBS, but that was 6 years ago. It's a pain, and more costly due to the fact that it's a special drilling compared to a regular CXP33 rim, just as your's is a special drilling of an open pro.
08-31-14, 12:03 PM
#17
SuperGimp
You have skills I wasn't even aware existed.
What does the brain trust say about replacing spokes if you replace the rim? I was under the impression that was generally a good practice and would open up some additional rim options for you.
What does the brain trust say about replacing spokes if you replace the rim? I was under the impression that was generally a good practice and would open up some additional rim options for you.
08-31-14, 08:52 PM
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09-03-14, 07:59 AM
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