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MountainBikeReview.com's Forum Archives - General Discussion
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So I screwed up big, please advise me! (14 posts)
|  So I screwed up big, please advise me! | saltybiker
Mar 28, 2003 6:59 PM | | Ok, so I sent my shock away to be serviced. I then decided to take my bike apart and give it a good cleaning. So fast foward to me reassembling my chain rings and I striped one of the bolts or socket rather that holds on the small ring. So I have three that hold and one that doesn't. So I need a new crank arm, right? The kicker is I just put in a new square taper bb. I have Deore Hollowtech cranks now, and was planning to upgrade to XT when they broke. Well I broke them. Should I try to find some old square taper LX or scrap the new bb and get the new XT? If there is another way to solve the stripped socket I would love to know, thanks
saltybiker |
| re: So I screwed up big, please advise me! | Philber
Mar 28, 2003 7:06 PM | | I think you can drill it out and put a heli-coil in it. It's basically a threaded plug. I've never used one, but I've heard they work very well. |
| You will never go wrong with XT | CCRiderKY
Mar 28, 2003 7:16 PM | | You deserve it! I have used Deore, LX, XT and Race Face. XT rocks! Go ahead (if financially able to swing it) and step up to the splined interface and new XT cranks. You will never have buyers remorse.
Just my $0.02 |
| Agree, Helicoil or Timesert first... | næstep
Mar 28, 2003 7:45 PM | | ...which should be withing the capability of practically any automotive shop if none of your LBSs can do it, or...
...skip XT and go with the LX splined. Pretty much the same damn crank at 1/2 the cost.
næstep |
| Are you sure | Will
Mar 29, 2003 4:14 AM | | The chain ring bolts are kinda odd. Very fine thread. Are you sure you can get a Helicoil for it. I've used them before but only in standard metric sizes. |
| "Coarse" and "Fine" inserts available... | næstep
Mar 29, 2003 9:03 AM | | I believe the chainring bolts are M6, just don't know the TPI or if they fall into the "fine" or "super-fine" category.
næstep |
| don't worry about it | crimethinker
Mar 29, 2003 6:26 AM | | If you still have 3 good bolts holding on the small ring, just screw in the stripped one as tight as you can make it (assuming you can get it to at least stay in the crank) and ride. I rode an old sugino crank years ago with that same problem and never regreted it. What do you have to lose? |
| don't worry about it | bikerboy
Mar 29, 2003 6:29 PM | | I agree. I have the same problem right now with my old Diamondback, except its a 5 arm crank which with one bolt missing might be a little more secure. But I say assuming that stripped or cross threaded bolt will stay, keep it. There isnt a whole lot of side to side deflection on the small ring anyways. Most of the force you get is when you are shifting from granny to middle and thats going to pull that rung towards the flange of the crank arm mount surface. So just go out and enjoy your ride knowing how much money you didnt spend on those new XT cranks. |
| Problem solved. | saltybiker
Mar 29, 2003 10:21 AM | | I went to my lbs and explaned what I did and walked out with a new XT Crankset and new es-70 bb. They only charged me 169.00 for everything so I think after I am done being angry at myself for stripping the crank, I will be very happy and excited about my new stuff. Thanks for all of your responses.
saltybiker |
| DOH! | næstep
Mar 29, 2003 12:54 PM | | Do yourself a favor and spend $20 on a torque wrench. I'm sure you'll enjoy the new crank, but the key to keeping the Shimano splines quiet and trouble free is proper torque on the crank bolt.
næstep |
| Yeah, that's a big 10-4 ... | Philber
Mar 29, 2003 3:18 PM | | When I installed my cranks, I just reefed down on 'em, like I usually do. They kept squeaking and then coming loose on the first two rides. Fortunately, Cook had an 8mm key on his multi-tool (I didn't on mine, but I do now), so I was able to keep riding, but stopping every 15 minutes to tighten them was a drag. When I torqued 'em properly with a torque wrench, they never came loose again. Lesson learned. |
| So is the goal to.... | saltybiker
Mar 29, 2003 4:39 PM | | get them super tight or to a recomended torque? If so what is the reccomended torque. Thanks again.
saltybiker |
| Recommended torque... | næstep
Mar 29, 2003 5:04 PM | | It'd be pretty tough to overtorque these enough to snap the bolt head off, but with these new hollow design they're using it may be possible.
Recomended torque values are 36 ft-lbs on the crank bolts and 50 ft-lbs on the bottom bracket. You can download installation instructions from http://shimano-europe.com/cycling .
Even if your LBS did the install for you, I'd double check the torque anyway. Not a slight against LBSs, but I've never seen a shop wrench with a torque wrench in hand, and tiny bolts have a habit of being overtorqued while big bolts are usually undertorqued.
A sure-fire way to ruin a crank interface is to ride it loose.
næstep |
| Recommended torque ... | Philber
Mar 29, 2003 8:56 PM | | Often, too tight is worse than too loose. That's because too tight can compress the metal and contribute to a stress fracture or riser. Too loose and it won't stay tight. Too tight and it might break. It's not hard to deform a lot of bike parts by over-torquing and thereby weaken them and the interface. You don't need to worry about most non-drive train parts (shifters, levers, cable anchors, tube clamps), but when it comes to critical parts (cranks, stem, rings) and certainly anything disc-brake related, a torque wrench is your best friend. |
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