Double BB Spacer - ...
 

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[Closed] Double BB Spacer - Will I die?

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A slight chainline issue on my new frame has lead me to come up with the solution of 2 drive side BB spacers, only problem being this is on a 73mm BB shell.

Non drive side crank seems to have tightened up ok but anybody done this before on standard Shimano HT2 cranks?

Will I be dying a horrible fiery death?

Cheers


 
Posted : 03/10/2018 7:26 pm
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If the BB cups screws-in at least 3 full turns then you'll be fine. With my RF Turbine cranks, standard install is 2 spacers under one cup.


 
Posted : 03/10/2018 7:37 pm
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I assume you fitted 2 on one side and non on other side if it's a 73mm ?

I had this issue on my rove when I fitted a triple.

Did exactly this and it's been grand since. Ridden it all over the place about 6000km since.


 
Posted : 03/10/2018 8:00 pm
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@trail_rat

Yes mate, 2 drive side and none on the other.

Thanks for the confirmation 🙂


 
Posted : 04/10/2018 9:50 am
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What you want is chainring spacers not crank spacers.  Otherwise your cranks won't be in the middle...  This may bother you, it may not.


 
Posted : 04/10/2018 9:55 am
 geex
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if you're really worried. Saint HTII cups are deeper (more threads)


 
Posted : 04/10/2018 10:10 am
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My cranks fell off after a few 100 miles when i did the same* by accident as the axle wasn't quite long enough to bottom out and torque correctly (rf self extracting type).

You may find similar.

Your bb will be fine so long as it engages a few turns as the cranks will prevent it unscrewing (by virtue of preventing it expanding)

*1 each side in practice rather than 2 on one side.


 
Posted : 04/10/2018 12:27 pm
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I've done it with an extra spacer as for some reason my XTR M970 cranks wouldn't bottom out. Never did completely figure out why as I even measured the frame and it was n spec.

Just be aware that the spindle might be the wrong length now which might cause issues. GXP spindles the drive side bearing sits on a rised bit of the axle, otherwise it creaks horribly, shimano should be fine as long as it's not miles off and the NDS crank still clamps it properly, raceface use something like the M970 which might be a problem.

Your bb will be fine so long as it engages a few turns as the cranks will prevent it unscrewing (by virtue of preventing it expanding)

Procession stops them coming out, that's why one side is a left hand thread.


 
Posted : 04/10/2018 12:45 pm
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My cranks fell off after a few 100 miles

...

Your bb will be fine so long as it engages a few turns as the cranks will prevent it unscrewing

😐

Procession stops them coming out, that’s why one side is a left hand thread

*cough* "precession" and given that BBs can loosen, it's never a guarantee.


 
Posted : 04/10/2018 1:06 pm
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BB'll be OK but my money's on you ****ing the LH crank within 6 months


 
Posted : 04/10/2018 1:10 pm
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You risk having the driveside BB cup stripping the threads on the shell as it doesn't have a long enough overlap to be stable.  I had a similar problem with setup on an older frame and did as has already been suggested above- Saint BBs driveside BB cups have a much deeper thread and therefore has much more overlap and stability in the frame.


 
Posted : 04/10/2018 1:12 pm
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I can't imagine the drive side BB cup will be an issue, it's designed to be used with 2 spacers when used on a 68mm BB shell after all.

What I am concerned about is the non drive side crank coming loose as it hasn't quite got enough axle to clamp down on.

Guess I'll find out.


 
Posted : 04/10/2018 1:57 pm
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I put 2 spacers on the chain side and none on the other to get a better range of alignment when I went 1x11. This was on a Hope HTII BB and everything has been fine.


 
Posted : 04/10/2018 2:06 pm
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Wow some quality over thinking here.

Molgrips. Good luck spacing my chainrings inwards to the chainstay with chainring spacers - not enough throw on the front mech to get on big ring

1.5mm to the left really is not noticeable, unless your Froome/cav /hoy.

"What I am concerned about is the non drive side crank coming loose as it hasn’t quite got enough axle to clamp down on."

2 spacer in one side rather than 1 on each side should mean that the width between cup faces is exactly the same and ergo clamping space on axle should be the same


 
Posted : 04/10/2018 5:37 pm
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On a 73mm BB shell the normal HT2 spacer usage is one on the drive side cup and none in the non drive side cup, so fitting 2 on the drive side cup will make the clamping space for the non drive side crank shorter than normal, hence the thread.


 
Posted : 04/10/2018 7:21 pm

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