Bicycle Mechanics - Chainring questions - pic attached.

Guys,

take a look at the attached pics of the large chainring on my wife’s bike. Hopefully the pics will be viewable. Anyway, I noticed these teeth were badly worn, so I removed the crank with the intention of stripping it and replacing the chainring.

I reckoned she must have bashed the ring sometime as only those teeth were damaged. But, here it gets interesting, the second pic is of the teeth directly 180 degrees opposite behind the crank arm. I think this is now a coincidence as bash damage to those teeth is almost impossible. I studied the teeth either side of the ones in the pics and there is almost perfect symmetry. The chainring does not have the conventional shifting ramps like the Shimano rings have, so I have the idea that these teeth were intentionally machined that way to facilitate shifting. Does that sound the likeliest explanation?

I also noticed that all three rings are riveted together so replacing a ring later is not possible. While I’ve got the crank off here are the questions I’d like answers to if you could help.

#1: Are these teeth intentionally machined or are the rings the product of sub-standard machining?

#2: Being a Suntour rings and cranks, should I scrap them as I get the impression that Suntour is now a no-no when it comes to choosing components. I might be wrong on that but I’ve seen a few threads on Suntour and none were particularly complementary.

#3: The middle chainring also looks messy. There appears to be no symmetry to the teeth and some are machined with unusual shapes. I get the impression that it just isn’t right.

#4: I also noticed the front der cage was about 8mm above the chain so this gets me thinking that the bike was made and assembled by a chimp under the close supervision of a clown. Funny thing is, the bike is a Dawes Edge mtb and it was given really good reviews. Maybe we got the Friday bike or the Monday hangover bike.

Ideas?

1-Some chain rings have a few smaller teeth to help the chain on to the ring.

2-Get some better rings.

3-Look at #1. Same principle or do you mean the teeth are not lined up? Bent?

4-Not set up right. Fix it.

Slainte:beer:

Originally posted by Bokkie

#1: Are these teeth intentionally machined...?

#2: ... should I scrap them ?

#3: The middle chainring also looks messy.

#4: I also noticed the front der cage was about 8mm above the chain ...

1. Yes
2. Yes, if they run roughly, shift erratically, or otherwise bother you.
3. May be intentional or at least harmless
4. Should be 1-2mm above the large chainring

Anyone who shifts properly (spin the cranks under light load) does not need pins, ramps, runt teeth, and other modern gimmicks, but they are at least generally harmless.

To clarify...

Suntour good

SR Suntour bad

The crank and rings are indeed SR.

I think a trip to the lbs is in order to get a better set. I wonder what kind of bb the chimp/clown combo decided to fit? mmmmm!

Thanks for go/no-go advice.

Originally posted by Bokkie
The crank and rings are indeed SR.

I think a trip to the lbs is in order to get a better set. I wonder what kind of bb the chimp/clown combo decided to fit? mmmmm!

Thanks for go/no-go advice. You probably need a new BB to match the crank anyway.

I just purchased a new Diamondback Topanga. The teeth looked like this (first picture, of the original message) right after i purchased it. It was brand new. I rode it awhile, it got worse, my brothers chain would mess up, so we took them back (dicks sporting goods) they repaired them (after misunderstanding by them as to if they were damaged :confused: ) SO to make a long story short. They are horrible, and the rear ones wobble! Are these just crap from the mnf. or are they just so cheap, my 20 or so miles of riding have ruined them? I have completely degreased (with brake cleaner - bad idea??) and re-lubed them each ride, with pedros dry chain lube.