Square Taper BB limit spacer

[maugurlene]

Hi Relja,
Thanks for your forum and videos, that help me a lot in bike repair learning !
Do you have any idea, what this washer on BB-UN300 is intended for ? No other BB's use this, so why is it there ? Maybe just to force customers to change their chainset when a bit used, and buy a brand new one. A bit annoying for vintage bike repair, I think !
Thanks for your answer
Maugurlene

 

[BikeGremlin]

Hi Relja,
Thanks for your forum and videos, that help me a lot in bike repair learning !
Do you have any idea, what this washer on BB-UN300 is intended for ? No other BB's use this, so why is it there ? Maybe just to force customers to change their chainset when a bit used, and buy a brand new one. A bit annoying for vintage bike repair, I think !
Thanks for your answer
Maugurlene

Hi Maugurlene,

The spacer is placed on the right hand side.

I've explained the proper procedure for installing square taper cranks and the risks of not doing it properly in this article: How to install square-taper cranks.

With that in mind, the noted spacer ring provides a crank arm stop at the exactly same spot (which can have benefits in terms of achieving a desired chainline as precisely as possible), without letting the crank arm ride higher up the spindle under pedalling load and reduce the tightening bolt's preload allowing it to unscrew.

A downside is that with some cranks, the stopper prevents the crank from achieving enough preload so it doesn't get damaged when applying torque (it fits too loosely on the spindle).

When that is the case, the stopper can be removed. It's a press-fit, so can be pried out, without damaging the spindle.

Relja