Chainring replacement
#2
Senior Member


Joined: Apr 2007
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From: Munising, Michigan, USA
Bikes: Priority 600, Priority Continuum, Devinci Dexter
Those look pretty good to me, and I think I'd run 'em as they are.
Replacing with another brand should be ok. The bolt circle diameter (BCD) is what to watch for. You need five-bolt rings at whatever BCD fits your crank arms.
Replacing with another brand should be ok. The bolt circle diameter (BCD) is what to watch for. You need five-bolt rings at whatever BCD fits your crank arms.
#4
Old fart



Joined: Nov 2004
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From: Appleton WI
Bikes: Several, mostly not name brands.
What makes you think the rings needs replacement? If they really need replacement, or you want to change your gearing, they can be replaced individually; you just need to match the "bold circle diameter" (aka "BCD") for them to work. It looks like your crank has the two outer rings the same BCD (probably 130mm) and a smaller BCD for the inner ring (probably 74mm).
#7
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From: 961' 42.28° N, 83.78° W (A2)
Bikes: Mongoose Selous, Trek DS
That's what I was referring to, not sure, as a novice, it just looks like about eight potentially troublesome teeth on the third chain ring.
#8
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Joined: Aug 2013
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It's a shift/chain release point. Look at the short teeth where the ring is engraved with the size. Then look at the middle ring in the same area; you'll see shorter teeth there as well. There are none on the small ring because on that ring the chain only needs to shift up and not down.
#9
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From: Pittsburgh, PA
Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!
What makes you think the rings needs replacement? If they really need replacement, or you want to change your gearing, they can be replaced individually; you just need to match the "bold circle diameter" (aka "BCD") for them to work. It looks like your crank has the two outer rings the same BCD (probably 130mm) and a smaller BCD for the inner ring (probably 74mm).

I'm pretty sure the outer BCD is 110 mm, not 130 mm and agree the inner is almost certainly 74 mm.
#10
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From: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
#11
Senior Member
Joined: Jan 2016
Posts: 2,344
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From: 961' 42.28° N, 83.78° W (A2)
Bikes: Mongoose Selous, Trek DS
It's a shift/chain release point. Look at the short teeth where the ring is engraved with the size. Then look at the middle ring in the same area; you'll see shorter teeth there as well. There are none on the small ring because on that ring the chain only needs to shift up and not down.
Much to learn, and, understand. Thanks.
#13
The points don't wear that much.
The valleys get wider, so that the chain gets purchase on fewer teeth at a time.
You can check somewhat by lifting the chain where it is wrapped around the chainring- good condition = little slack,
poor condition = chain lifts away from the chainring (this also reflects on the state of the chain).
Try it on the different rings- the middle gets the most wear typically.
The valleys get wider, so that the chain gets purchase on fewer teeth at a time.
You can check somewhat by lifting the chain where it is wrapped around the chainring- good condition = little slack,
poor condition = chain lifts away from the chainring (this also reflects on the state of the chain).
Try it on the different rings- the middle gets the most wear typically.
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marcpro
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