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Tensile bb + Tensile cranks = bad fit


sideburn2

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Anyone ever had this problem?

Tensile isis bb and Tensile optimum crankset

Was fitting my new cranks and bottombracket and could not even get the cranks far enough in on the splines so the bolts could reach the threads?

Had to hammer the cranks in with a mallet and then finally the bolts reached but literally screamed as i turned them in

Appreciate any kind of input, hope to solve this with a new bb, sucks though

 

// Patrik

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New cranks will often be really tight on splines - usually just a LOT of grease is the key, on both the splines, the inside of the BB threads, the crank bolt and under the head of the crank bolt too.  Tapping the cranks on with a rubber mallet can be fairly common with some new cranks.  It's a good sign though, it should mean the cranks last longer and don't end up developing play - if they went on easily it'd be more of a concern.

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Hi! Thank you for the reply

Ive had multiple isis cranks, never had this issue with middleburns etc

My concern is that there is only about 8-10mm of splines inside the crank, i would like to bottom the crank out against the bb, i feel like there isnt enough to spread the load for hard riding, shouldnt be this tight

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How much grease have you used?

Usually the cranks won't bottom out fully against the stopper on the crank arm.  There's a very slight taper on the cranks that should stop that from happening.  If they're super worn they will do, but not all will.  I've had a few combos in the past (Try-All cranks on a Trialtech BB) where there was a bit more of a gap, but without seeing a photo it's hard to say for sure if it's 'right' or 'wrong'.

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Thank you for your replies! I have used plenty of assembly-grease, i have never experienced this before, as you can se from the bolts i can only lock the crank with about 2-3 mm of thread before im afraid that i will strip the bolts, you can see where it stops on the locktite

And you can also see more than half the splines still to go inside the crank when mounted on the bb

20170106_095624.jpg20170106_095418.jpg20170106_095617.jpg

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Took some reference pics of my cannondale with middleburns, i even have to hammer the crank in so the bolt can reach the threads on the bb on the tensiles

Edit: i just tried the tensile crank on the fsa isis bb on my cannondale and vice versa, and confirmed that the cranks is the issue, which sucks, the middleburns slips right on the tensile bb and the bolt locks it snug, but i have to hammer the tensile cranks on the fsa also to get the bolt to reach the threads... f#ck

 

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If the Middleburns are older they will have worn in a bit so they will fit better.  I've seen people with new cranks that sit a similar distance away from the stopper and they've worked out fine - you just need to keep on top of making sure the crank bolt is tight when you're out riding.

You'll be able to get a lot more torque through the crank bolts if they're greased too.  It looks like the bolt is dry as are the threads in the BB, so that won't be helping you get them tighter.

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There is no way the crank sits "fine" on the splines just 25-30% of the way, but i can see your point and loads of people would probably just go with it and tighten as they go and the cranks got worse and worse, i have compared the middleburns splines to the tensiles and the middleburn had a machined recess between the splines while the tensiles doesnt, and on the splines on the bb the recess are a radius, so im pretty sure thats why they wont fit, i will file the recess carefully until the tensiles fit snug on the bb as i would like, really shouldnt be like this but hey, i gues ive been lucky before with all my other cranks

Thank you Mark for the feedback!

// Patrik

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Cranks will always bed in, so you will always need to re-tighten a new pair of cranks regardless.  As mentioned before, ISIS splines sit on a taper so they won't/shouldn't totally bottom out on the end of the spline on the BB axle either. 

As before, you'll probably be able to tighten the crank onto the BB a lot more if the bolt is actually greased too.  It will be feeling way tighter than it actually is simply because of that.

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