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Discussion Starter · #1 ·
I have a 2010 Cannondale CAAD9-4, SRAM Rival equipped with a SRAM Force crankset (totally stock bike).

I got the bike in May, and after a short bit of riding (maybe 60 miles), I noticed a squeaking from the bottom bracket, after riding up a big hill (standing up on the pedals). It turned out the left crank arm was loose, as I could wiggle it very slightly with my hands. I promptly took the bike back to the LBS where I bought it, and the mechanic tightened the crank arm back down right away, and I left with the bike.

So, now I've put about 500 more miles on the bike. It went back to the LBS for a tuneup/checkup at around 300 miles. This past weekend, on a long, hilly ride (lots of standing on the pedals), the bottom bracket area started squeaking again. I pulled over, and found the left crank to be slightly loose again. I tightened it down with my multi-tool the best I could, and that seemed to fix it for the rest of the ride. FWIW, I weigh about 175 pounds and am not a particularly strong rider - meaning the bike is not abused nor subjected to higher than average loads.

The question is, this being a BB30 bike, could my left crank arm be damaged from improper assembly at the LBS, or can I just tighten it back down and keep riding? From what I've found online with square-taper bottom brackets, the left arm can become permanently damaged if improperly installed/tightened and rode at all in a loose state. The bike probably has 10 miles of squeaky riding on it.

From what I've found for the SRAM BB30 bikes, the crank arm is splined rather than a square-taper press fit. Is this type of connection also prone to damage if pedaled when loose? If so I plan to take it back to the LBS and demand a new left crank arm. If not I'll just torque it down to spec, check it every few hundred miles, and keep riding.
 

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When the LBS re-tightened the crank arm, did they use a torque wrench?

If the splines are damaged, then the crank arm will never fasten down properly. And will continue to loosen up, no matter how many times its tightened down.
 

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Discussion Starter · #3 ·
frdfandc said:
When the LBS re-tightened the crank arm, did they use a torque wrench?

If the splines are damaged, then the crank arm will never fasten down properly. And will continue to loosen up, no matter how many times its tightened down.
Honestly, I have no idea...the guy wheeled it in the back to "tighten it up" and then gave it back to me a few minutes later. I'm thinking that they never properly tightened it on the intiial assembly, which is why it came loose so soon at first.
 

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dirtroadrunner said:
Honestly, I have no idea...the guy wheeled it in the back to "tighten it up" and then gave it back to me a few minutes later. I'm thinking that they never properly tightened it on the intiial assembly, which is why it came loose so soon at first.
Not that it really makes much of a difference to your claim, but initial crank installation on a stock bike is usually done at the manufacturer's facility. However, good shops check crank tightness (among many other things) before customer delivery. So yes, complain.
 

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Discussion Starter · #5 ·
I ended up running it back to the LBS. The mechanic took apart the bottom bracket (in about 2 minutes, no less) and found that an extra plastic spacer had been added that wasn't needed (long story but I wrecked the bike just after getting it and the LBS built it up with a replacement frame - the old frame probably needed the spacer but the new one didn't). He showed me the splines and they looked OK, besides in a few isolated spots where some of the black coloring was worn. He put it back together with some Loctite on the threads and torqued it down.

I'm going to check the torque on it every few weeks and take it back again if I find that its getting loose. Hopefully this fixes it.
 

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No lock tite is required for the Sram cranks. Only grease and a torque wrench.
 

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frdfandc said:
No lock tite is required for the Sram cranks. Only grease and a torque wrench.
Agree. Loctite on a crank fixing bolt is a desperate measure employed by those who are at their wits' end. Finding another mechanic or LBS might not be a bad idea.
 

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Discussion Starter · #9 ·
I've already found another mechanic (me). The only reason I took it to the LBS is to remove any fault from myself if I need a new crank arm (i.e. "I bought the bike from you, you repaired it, messed it up, and are responsible for fixing it). If I work on it myself or take it to another LBS, the current LBS could claim that I or the other shop messed it up.

I really don't like the LBS I bought the bike from, but any future chance of getting a free replacement crank arm, if mine is indeed damaged, will be lost if I take the bike to a different LBS.

I'm taking the bike on a very hilly 50ish miler this weekend and will check the crank bolt torque before and after...
 

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dirtroadrunner said:
I'm taking the bike on a very hilly 50ish miler this weekend and will check the crank bolt torque before and after...
Let us know what you find. And it's good to hear you're taking matters into your own hand. With the internet in general and the helpful people here on RBR, information is just a click away.
 

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The only place to use Loctite on a BB30 set up is the bearings.

Put some green Loctite on the bearings to keep them in the frame. If not, they will come loose and start creaking.
 

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Discussion Starter · #12 ·
wim said:
Let us know what you find. And it's good to hear you're taking matters into your own hand. With the internet in general and the helpful people here on RBR, information is just a click away.
I appreciate the help very much...helpful folks on various forums have taught me much about working on my own vehicles, and now bikes too.

I checked the torque on the bottom bracket before and after my ride...my torque wrench clicked at 38 ft-lbs both times (the BB says 476 in-lbs max, or just shy of 40 ft-lbs). I didn't want to over-tighten it so I left it alone after that. So it seems good for now, but I plan to check it every week or so to make sure it stays tight.

On another note, I enjoyed a great 50 mile rural and scenic ride on the bike, with 3000 feet of ups and downs to boot.
 

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I recently bought a nos cannondale R700 with a Truvative Crank and it appear the internal nut on the non drive side has backed out
 

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bikemagg said:
I recently bought a nos cannondale R700 with a Truvative Crank and it appear the internal nut on the non drive side has backed out

Did you try to tighten it? Does it turn? More information needed to assist you.

Or since you just purchased it, take it back to the LBS since its something that should have been checked and corrected before you took delivery.
 
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