Bike Forums - Chainring Help

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Files

09-04-18 06:39 PM

Chainring Help

So I replaced my chain today because it was worn out. But I noticed that the chain is loose at some parts and tight at others of the chainring. I recently got a new wheelset and cog so the chain and cog are new so does that mean the chainring is the part needing to be replaced?

JohnDThompson

09-04-18 06:57 PM

Quote:

Originally Posted by Files (Post 20547097)

I noticed that the chain is loose at some parts and tight at others of the chainring. I recently got a new wheelset and cog so the chain and cog are new so does that mean the chainring is the part needing to be replaced?

Either the chainring isn't perfectly round or the mounting places on the crank aren't perfectly co-axial with the bottom bracket. Sometimes you can minimize this by changing how the ring mounts on the crank spider (see the section on "Centering chainrings" in this article: https://www.sheldonbrown.com/no-derailers.html). You might not be able to get it perfect, but some amount of off-centeredness is seldom a problem unless it is so severe it allows the chain to derail.

seamuis

09-05-18 07:57 AM

So you replaced the chain and rear cog but not the chainring, correct? If I understand what you’re saying, common sense would dictate that your cog isn’t round. I would check that first, by swapping my rear cog out for an old one and then checking it. Because if you didn’t change your chainring and you didn’t have this problem before then it couldn’t be the chainring causing the issue.

REDMASTA

09-05-18 08:16 AM

Very common, I wouldn't worry too much about it. You can try chasing the problem and installing a different cog, chainring, or even the crankset; any of those being off just a little will cause it. Or you can just set the chain tension at the tightest point and you're gtg. It won't cause any problems long as you're not dropping the chain as John already stated.

CBee	09-05-18 10:43 AM

I’ve been looking everywhere for one of these aarn chainrings. Anybody have a line on one?https://cimg9.ibsrv.net/gimg/bikefor...57ff948cd.jpeg

REDMASTA

09-05-18 12:07 PM

Good luck. You can get on the email list at 44rn.com but they don't restock them very often, and when I'd finally get a notice they were sold out before I could order. Recently picked up a used B&W camo edition in good condition from someone on the pedalroom marketplace. They pop up there from time to time so that's probably you're best bet. The bike I originally wanted to use a black Aarn chainring on I ended up just getting a Lattice instead, it's similar and pretty nice too (they also come in silver).

https://cimg2.ibsrv.net/gimg/bikefor...d8cf1c6c5.jpeg

CBee	09-05-18 12:58 PM

Quote:

Originally Posted by REDMASTA (Post 20548600)

The elusive aarn... Guess I shouldn’t get my hopes up.

CBee	09-05-18 01:04 PM

Anybody ride one of these? I kinda like the old school box look of it.https://cimg3.ibsrv.net/gimg/bikefor...3a682b572.jpeg

seamuis

09-05-18 03:05 PM

Quote:

Originally Posted by CBee (Post 20548747)

Anybody ride one of these? I kinda like the old school box look of it.https://cimg3.ibsrv.net/gimg/bikefor...3a682b572.jpeg

I’ve ridden the 3/32” 130bcd version
https://cimg4.ibsrv.net/gimg/bikefor...8faf13c90.jpeg

CBee	09-05-18 03:09 PM

Quote:

Originally Posted by seamuis (Post 20549022)

I’ve ridden the 3/32” 130bcd version
https://cimg4.ibsrv.net/gimg/bikefor...8faf13c90.jpeg

Looks good. What did you think of it?

seamuis

09-05-18 03:43 PM

Quote:

Originally Posted by CBee (Post 20549030)

Looks good. What did you think of it?

I replaced it with a larger ring. (The one pictured is 55) it’s a good ring overall. I actually quite like the ‘W cut’ teeth profile. Felt quite stiff and performed fine. Nothing special about it i suppose but a solid choice if it’s your style, and as a bonus can pretty regularly be found relatively cheaply, NOS on eBay. One thing I did notice though, is that the forging wasn’t as good as the later ‘SG’ type rings like those on 74XX series. You could see it on the side/edges of the ring as a rather rough surface. But in fairness that was typical of a lot of 70s era chainrings, as I’ve had plenty of old campy rings that looked the same. Less refined is how I think I’d describe it.

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