# Can I overtighten my cranks?



## MisterC (May 26, 2007)

I find lately that, as I ride, my cranks get slightly loose. Wherever I stop I will pull out my multi-tool and I can tighten it down a bit and it is better. I figure I don't have the leverage with such a small tool to tighten it down enough to hold.

Or maybe I need some locktight? I dunno, is this a common problem?

Cranks and BB are Dura Ace. And, as we discussed, I ride brakeless so the pedals see a lot of pressure in both directions.

Tightening something every ride is no big deal but every few miles miles is annoying and I don't want it to get worse.


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## android (Nov 20, 2007)

Dura Ace 7400 series track cranks?

If you didn't correctly tighten them with a torque wrench the *first time* and now they are coming loose on a regular basis, they are ruined.


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## FatTireFred (Jan 31, 2005)

can you overtighten? yes... should you? no. should they be coming loose? no


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## Dave Hickey (Jan 27, 2002)

If either the square taper(7600) or octalink(7710) track cranks are coming loose on a regular basis, it means you rode too long with them loose..

Try loctite but no guarantees


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## cglazowski (Jul 16, 2007)

Try tightening it with a longer wrench before the ride. A multi-tool of which the lever arm is maybe 2-3 inches will need about 150lbs of force to reach the proper torque range. Are you standing on your multi-tool when tightening them? If not, you are probably not reaching the proper torque.


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## Richard (Feb 17, 2006)

If they won't stay tight, then it's likely you "rounded off" the fitting on the crank arm. If so, it's toast.

We see this all the time on cheap "mass-market" (read Walmart) bikes that weren't properly assembled in the first place. But it can happen to the best components if ridden "loose."


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## PeanutButterBreath (Dec 4, 2005)

Square taper cranks have a torque spec that you are unlikely to achieve with a mini-tool. Hopefully you didn't ruin the crank arms, but if they are ridden loose the become irreparably damaged pretty quickly.

This is why it is nice to have a torque wrench (two, really). Even if you don't use it every time (i.e. when you are on the side of the road) you can at least develop a feel for what proper torque should feel like. You will also realize the jobs for which a mini-tool is never going to cut it.


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## MisterC (May 26, 2007)

So angered that I must learn every lesson the hard way.

I didn't install these things but right after I got them home I took them out and they came loose, really loose, like moving around in the BB shell a lot and the arm was "jumping" on every stroke so much that I was nervous and walked the thing home.

So I took them to a mechanic at a different shop (but he owns the shop I took them to originally (Larry)). I figured he knew what was up. So he tightened them to what he claimed was 100 lbs of pressure and said, "You need to tighten these after your first ride."

Well, nobody told me and, to hear it from you guys, no I don't, they should be tightened enough when they are installed. That's why I take things to bike shops, they are "experts".

Should I, or do I have the right to, go to the shop that installed them and tell them they installed them incorrectly and therefore ruined them? I don't know if they will replace them but it's worth a shot if it can be attributed to them. If it was my mistake then I don't want to through a fit just for the sake of it.

Oh, they are 7710.


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## cglazowski (Jul 16, 2007)

Hm, I'd be wary of a mechanic that didn't know the difference between pressure and torque. Torque is a force times a distance, like inches times pounds, hence most bike torque specs are put in units of in*lbs (or N*m, newtons times meters). Pressure is a force over an area, like psi, pounds per square inch. I bet he tightened them to 100 inch pounds, which is about 1/4 of what it should be. Have them tighten them to 400 inch pounds, or if you are riding it hard fixed, i.e. skid stops, tighten them even more.


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## wim (Feb 28, 2005)

*Bad install.*

Dura-Ace 7710s are Octalink cranks and, if installed properly, really don't need to be retightened after the first ride. My guess is that these cranks were improperly installed. It's very easy to misalign the Octalink splines when fitting the crank to the spindle, then hose down on the wrench and put the crank on the road to ruin. The Shimano service instruction sheet carries a caution note to that effect (upper left hand corner). If the splines did get aligned properly, I agree with cglazowski that the crank was tightened insufficiently during the initial install.


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## peyo (Aug 5, 2008)

This is why I have a torque wrench. I tried to get the recommended torque specs from my normal 8" allen key and it was darn near impossible. 

Anyway, you didn't torque it down enough on the first install. As mentioned above, try Loctite but that will not guarantee it'll remain tight from here on out. It seems that with Octalink, you only need to improperly install it once to hose the cranks.

As for the splines lining up, I always remove the dust covers on the self-extracting bolts so that I can see if the splines are aligned before I torque the cranks onto the BB. Then you can install the dust caps with the spanner tool that comes with the DA cranks.


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## MisterC (May 26, 2007)

Well, today was a good day of sorts.

The crank arm is ruined. The spline has this odd step pattern that I will try to get a picture of (if anyone is curious) the guy (well two guys) who checked it out were taken back by it.

I didn't want to ruffle feathers where it was installed nor am I trying to embarrass anyone so I took them to a nearby shop to have them looked at and they confirmed yoru suspicions. So I went to the place of install and told them the whole story and the guy who listened was very pleasant and assured me he would make it right.

Bad news is the part is coming from Shimano and will take a week or so which might as well be an eternity without my favorite ride in these fleeting summer days.

Only thing I am worred about and he didn't seem to be is the other crank arm. What is the chance it has been damaged as well?

Very happy that the shop is taking admitting fault and making it right and that's all you can ask for. Mistakes happen, sometimes they happen to you.

Overall, good day.


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## Thommy (Sep 23, 2003)

Therer are two versions of Shimano's Octalink bottom bracket. I don't recall what your crankset uses right now, but you need to find out and buy some replacement Octalink bottom brackets especially if they are Version 1. Stock up or be forced to upgrade.


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## MisterC (May 26, 2007)

So strange that if you order the 7710 track cranks and the 7710 BB you could be installing incompatible parts


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## peyo (Aug 5, 2008)

Yeah, there are two versions of Octalink. If one of the crank arms is hosed, you should examine the bottom bracket to see if the splines are damaged. 

In any case, it's usually the non-drive side crank arm that gets loosened. I assume that they are open to replacing only one of the crank arms? If that's true, just make sure that the undamaged side is properly torqued. My buddies didn't believe me when I said that Shimano recommends 305-435 in. lbs. for the crank arms.


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## PeanutButterBreath (Dec 4, 2005)

Thommy said:


> I don't recall what your crankset uses right now, but you need to find out and buy some replacement Octalink bottom brackets especially if they are Version 1.


Octalink V1 is for road and XTR M952. V2 is for all other mountain. Versions of both are still being distributed, including the BB-7700 version (V1).

I gather that Hollowtech II might be a tough sell to the NJS. If so, the BB-7700 may be around for quite a while. :thumbsup:


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## PeanutButterBreath (Dec 4, 2005)

MisterC said:


> So strange that if you order the 7710 track cranks and the 7710 BB you could be installing incompatible parts


That shouldn't happen. I don't know if there ever was a BB-7710, but the BB-7700 is the currently spec'd BB for the FC-7710 (http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/road/Dura-Ace_Track.html).

If someone ordered the FC-7710 and then tried to save a little money on a lower spec BB, they could run into trouble with the V1 & V2 options if they weren't aware of the difference.


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## wim (Feb 28, 2005)

Yes, there's a BB-7710. Has v1 splines and fewer seals than the BB-7700. No mismatch with the FC-7710 is possible.

9 times out of 10, an Octalink crankarm gets ruined by just pushing it straight on the BB axle, then tightening. You have to wiggle it on. Then, _before tightening_, you should step back from the bike and see if the crank is exactly 180 degrees out from the opposite crank. If you didn't get the splines aligned just right, the crank's misalignment with its counterpart is easily seen.


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