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Discussion Starter · #1 ·
I ride a Trek 1500 and have abou 4,500 miles on it since I purchased it last summer. About 1 1/2 weeks ago I took it to the LBS I purchased it from for a tuneup since they gave me free tuneups for 1 year as part of the purchase. I really wasn't having any problems other than needing an adjustment to the fd. Anyway, after getting the bike back, I went out and rode it and the left crank arm came loose after 5 miles. It had never come loose before. I just figured they forgot to tighten it all the way. I tightened it and rode on. Since the tune up I've ridden a little over 200 miles and have had to tighten the left crank about every 20 to 25 miles. I thought it would eventually be OK. I'm planning on taking it back to my LBS tomorrow but I'm curious if anyone knows what they might have done? It seems like I should be able to fix it myself but I can't seem to get it to stay tight.

thanks
 

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Discussion Starter · #3 ·
CurbDestroyer said:
Take the crank arm off and clean all the threads . . . inside and out . . . All of the threads and all of the bolts. Then put blue loctite on the threads and re-assemble. Use Blue only . . . don't . . . do not use the red kind. The red kind might make it permanent. Use Blue Only.

So where do I get blue loctite? Is that a brand name? I kind of assume that my LBS would know that but maybe I'm assuming too much. If I can do it myself then I've learned something and I appreciate the help.
 

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loctite is a brand. blue loctite is the type of loctite. you can get it at any hardware store.

i doubt the left arm loosening has anything to do with the tuneup, unless they pulled the BB or something. and most shops dont clean up your bike. they just do the work. i would take it back to the shop and tell them what happened, and continues to happen.

what kinda crank you got?
when i got my truvativ bb/cranks last year, after the first two rides the left crank arm came loose. then off. i contacted them and they said if the arm isnt torqued to spec (which it was) the arm would come loose. and because the BB/crank interface uses a tapered spline, teh arm was shot. i wrote back it was torqued properly and they fessed up it was a problem. they worked with the company i purchased th part through and sent me a new left crank arm.
so far, so good.
 

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Discussion Starter · #5 ·
weltyed said:
loctite is a brand. blue loctite is the type of loctite. you can get it at any hardware store.

i doubt the left arm loosening has anything to do with the tuneup, unless they pulled the BB or something. and most shops dont clean up your bike. they just do the work. i would take it back to the shop and tell them what happened, and continues to happen.

what kinda crank you got?
when i got my truvativ bb/cranks last year, after the first two rides the left crank arm came loose. then off. i contacted them and they said if the arm isnt torqued to spec (which it was) the arm would come loose. and because the BB/crank interface uses a tapered spline, teh arm was shot. i wrote back it was torqued properly and they fessed up it was a problem. they worked with the company i purchased th part through and sent me a new left crank arm.
so far, so good.

I have an Ultegra crank. I think the LBS did grease the BB so I'm assuming they pulled the crank arm off. I think I'll let them look at it first in case there's something serious going on here. Thanks for the advice.
 

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weltyed said:
loctite is a brand. blue loctite is the type of loctite. you can get it at any hardware store.

i doubt the left arm loosening has anything to do with the tuneup, unless they pulled the BB or something. and most shops dont clean up your bike. they just do the work. i would take it back to the shop and tell them what happened, and continues to happen.

what kinda crank you got?
when i got my truvativ bb/cranks last year, after the first two rides the left crank arm came loose. then off. i contacted them and they said if the arm isnt torqued to spec (which it was) the arm would come loose. and because the BB/crank interface uses a tapered spline, teh arm was shot. i wrote back it was torqued properly and they fessed up it was a problem. they worked with the company i purchased th part through and sent me a new left crank arm.
so far, so good.
I must have the same Truvativ crank. It used to come loose all the time. ( I mean even more so than it should, I've had a lot of cranksets in my time.). tore it all apart, clinicaly cleaned everything, reassembled using Blue Loc-Tite on the threads and so far, so good.

Like the guy said, It doesn't take put 5 miles for it to come loose, and that's when everything is clean, and freshly torqued down without loctite. You can even re tighten them past the torque recommendations and within 5 miles they will come loose again. I just couldn't believe it since the arm has 2 pinch bolts, along with set screw. That 3 bolts coming loose within 5 miles. There's something wrong there. However the Blue loctite doesn't allow the bolts to back out.
 

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If the LBS let you out the door after not properly re-installing your crank arm, and the crank/BB interface is now deformed such that it won't stay tight after being ridden in the condition they gave it to you, they owe you a new crank arm.
 

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I think the LBS did grease the BB

No, it has a sealed brg. There is no reason they would pull the crank, unless they were cleaning it, and that's not part of a "tune up".
 

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That would be some tuneup

PeanutButterBreath said:
If the LBS let you out the door after not properly re-installing your crank arm, and the crank/BB interface is now deformed such that it won't stay tight after being ridden in the condition they gave it to you, they owe you a new crank arm.
True, but I'm with the Grump on this. It would VERY surprising to hear that the shop had pulled the crank arms off as part of the "1 year of free tuneups" deal. I suspect the loosening was pure coincidence, but the only way to find out is to ask the LBS what they did.
 

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Discussion Starter · #10 ·
OK, I took my bike in Friday. Thye said they didn't pull the cranks as part of the tuneup. They tightened the left crank with a torque wrench. They put a lot more pressure on it then I believe I was doing without the torque wrench. I think I was afraid of over tightening it. They said the cranks need a lot of torque and basically can't be over tightened. The loose crank appears to have been a coincindence. Went out and rode 40 miles yesterday with no problem. I appreciate all of the input.
 
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