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-   -   Bent middle chainring tooth (https://www.bikeforums.net/bicycle-mechanics/1273459-bent-middle-chainring-tooth.html)

fieldspring 05-28-23 11:34 AM

Bent middle chainring tooth
 
I have noticed a bent over tooth on the middle chainring of my 1999 specialised rockhopper mtb and wondered whether it is supposed to be like this for chain pick up purposes ? Otherwise I will attempt to straighten it as it seems to be causing interference in the lower gears - in the smallest chainring and higher rear sprocket gears a clicking and causing of a jumping sensation whilst peddling . Does anyone have any ideas ? Thanks

soyabean 05-28-23 12:48 PM

It prolly rolled over a curb, I see it all the time.

Vise grip and eyeball it.

Andrew R Stewart 05-28-23 06:08 PM

Except I prefer an adjustable wrench if it can fit. Andy

Bill Kapaun 05-28-23 06:14 PM

IF it's a "shift aid", they'll typically be "several", evenly spaced around the circumference of the ring.

alcjphil 05-28-23 06:25 PM

It would be vanishingly rare for a tooth on a middle chainring to be bent. Teeth on big chainrings often hit things as you ride over obstacles however

Andrew R Stewart 05-28-23 06:26 PM

Agreed. I can't count the "broken off teeth tops" I have fixed over the phone with a customer:) Andy

soyabean 05-28-23 08:49 PM


Originally Posted by alcjphil (Post 22905118)
It would be vanishingly rare for a tooth on a middle chainring to be bent.

Wanna bet?

JohnDThompson 05-29-23 06:23 AM


Originally Posted by soyabean (Post 22904863)
It prolly rolled over a curb, I see it all the time.

Unlikely on a middle ring, at least without damaging teeth on the outer ring as well.


Vise grip and eyeball it.
That usually works, and if it doesn't, you're really no worse off.

soyabean 06-01-23 12:54 PM

4 Attachment(s)
Why does everyone think curbs are perfect with straight edges?

And for those that didn't know, rocks in the park are also just as imperfect.

Hondo6 06-02-23 08:38 AM


Originally Posted by soyabean (Post 22909343)
Why does everyone think curbs are perfect with straight edges?

And for those that didn't know, rocks in the park are also just as imperfect.

"Unlikely" doesn't mean "impossible". But since the typical chainring spacing is about 5mm - and the large chainring protrudes farther towards the ground and is outboard - it would almost certainly take an incident involving relatively unusual geometry to damage a single tooth on the middle chainring without also damaging the large chainring next to it.

Yeah, it could happen. But that's not a bet the proverbial "smart money" would make.

fieldspring 06-02-23 12:48 PM

Thanks
 
Thanks for all comments to do with bent tooth on middle chainring. I decided that it had been damaged and bent due to some incident, though we could not remember what it would have been. Took the chainrings apart and hammered the bent tooth flat and the shifting and clicking has been resolved- hoorah ! Must have been a freak accident. Just goes to show that sometimes the unlikely event can be the cause of a problem even though our rational minds are telling us otherwise.

Pop N Wood 06-03-23 06:56 AM

I've bent all sorts of chainring teeth when the chain gets hung up shifting under power.

Just bend them back, replace the rings when they wear.


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