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Discussion Starter · #1 ·
View attachment 282962

Any ideas on replacing a crank? I will take it to the LBS but trying to get ideas on what to buy.

Also, if this was possibly caused by a low speed tumble a few weeks back, I am wondering if my handlebars are safe since I landed on them as well that day and again today.

Really having lousy luck with this bike the last month or so.

To make it worse after patching myself up and hopping on the old bike, I realized that was way overdue for a tune-up. So now I need to put a bike rack on to go to the LBS. Plus I did not get to ride today. :(
 

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Discussion Starter · #8 ·
It's really hard, if not impossible, to beat Shimano cranks for functionality per price. Unless you're a weightweenie I'd get whatever level Shimano (DA, Ultegra, whatever) fits into the overall picture.
Thanks. It is definitely a consideration. Bike is all Sram. But the LBS told me that I might be better off with Shimano derailleur due to some other issues.

And I got another rec for Ultegra.
 

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I'm assuming you weren't injured when the crank failed.

Carbon for cranks, bars, and stems is stupid. It's failure mode is very quick so there's a greater potential for injury. Sure, aluminum cranks have failed but their reliability record is much better than carbon and their failure mode is slower, so there's more possibility you'll discover the crack before your crank fails.

Buy an aluminum crank from any of the Big Three and ride happy.
 

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Discussion Starter · #13 ·
I'm assuming you weren't injured when the crank failed.

Carbon for cranks, bars, and stems is stupid. It's failure mode is very quick so there's a greater potential for injury. Sure, aluminum cranks have failed but their reliability record is much better than carbon and their failure mode is slower, so there's more possibility you'll discover the crack before your crank fails.

Buy an aluminum crank from any of the Big Three and ride happy.
Yeah. I fell. And could not figure out what happened. Felt like something locked up. Only about a mile from home so started soft pedaling home with only the right foot clipped in, just in case something went wrong I could get the left foot down. On a steep climb I decided to clip in just for that. And off it came. Sure it broke before but that was a sight.

Just spoke with the LBS, how much of a difference in vibration does an aluminum handlebar make, that is busted too. At least it was the crank that failed. And not the handlebar, say on last weeks 50 mph descent. Ouch.
 

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I'm surprised that no one has recommended another carbon crank and handlebar. When a carbon fiber frame fails, folks are quick to recommend another CF frame. We point out that while CF technology in bicycling is relatively young compared to its metal counterparts, development of higher quality CF and manufacturing are improving all the time. Can we not assume the same for CF cranks, handlebars, stems, seat posts, etc.? Why is it that we only trust CF for certain parts of our bikes?
 

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Discussion Starter · #16 ·
I'm surprised that no one has recommended another carbon crank and handlebar. When a carbon fiber frame fails, folks are quick to recommend another CF frame. We point out that while CF technology in bicycling is relatively young compared to its metal counterparts, development of higher quality CF and manufacturing are improving all the time. Can we not assume the same for CF cranks, handlebars, stems, seat posts, etc.? Why is it that we only trust CF for certain parts of our bikes?
I am thinking of going alloy but not really crazy about additional vibration in the handlebars. Tarmacs are hardly comfy in that respect to begin with.
 

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Thanks. It is definitely a consideration. Bike is all Sram. But the LBS told me that I might be better off with Shimano derailleur due to some other issues.

And I got another rec for Ultegra.
Don't think a Shimano derailleur will work if you've already got SRAM shifters. It will be very expensive to convert over.

As for your carbon crank, this seems like an extremely rare failure, so that wouldn't sway my decision if you aren't too concerned about weight and cost. Otherwise, some very nice aluminum cranks out there. SRAM Rival cranks sell really cheap (like $80) used on ebay (since you said your bike is SRAM equipped). A lot of these are super low mileage from people upgrading for weight (and ego!).
 

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Discussion Starter · #19 ·
No idea why a Shimano derailleur would be any better than a Sram one other than making you have to get new shifters and having a lighter wallet.
Apparently a few of the guys at the shop had the same problem I was having. The Force front derailleur was not picking up the chain enough to consistently shift to the big ring. The mechanic switched a few of those Force derailleurs to Ultegra and they worked. No new shifters needed. So far mine has been ok since the last tune, but if he did it to his own bike with no upside, I do not see the upsell.
 
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