RoadTire 

Who has alu chainrings cheap? I figure out it is the middle chain ring that jumps by getting on a hill and standing on the pedals. No jumping or skipping on the small or large chainring. Looking to do a cheap fix. (I replaced the chain, it was 12-1/4 inch! Also the rear cluster.) Bike is a used Raleigh Talus 8.0.

Post # 7 I tried to clarify a bit)

(Sidenote: most of my riding will be low-gear on Singletracks, not much gravel or time will be spent in the large chainring. Also it didn't take the brand new chain long to rust - just a couple rides this winter and bucket wash when done. Sheesh)

Cranks are Shimano Octalink MC361 42 - 32 - 22 T, BCD 104 / 64 mm

Addendum: 2010 Talus, 8 speed. MC361 on the bike specs, but I could only find Shimano Tech docs for FC-M361

cale

If you don't lubricate the chain immediately after washing, it'll rust.

Hmm... where to start looking for rings...32T chainring | eBay

RoadTire 

I haven't had to replace a chainring before, so am unsure about compatibility issues with the current 8 speed triple. Will any 32 tooth 8 or 9 sp chainring with 104 mm BCD work and are there some brands I should avoid?

Tunnelrat81

I know for double road cranksets, it's important to either replace a worn chainring with an OEM one or to replace all the rings together. This is because the ramping/pinning that facilitates smooth shifting is designed to be aligned between the various rings. Even a small road chainring from a double crankset that doesn't have any special ramping needs to be 'timed' properly with the large chainring so as to deliver the chain properly during upshifts. I don't have personal experience with this, or with swapping single rings out with non-oem ones to test this theory. I would have to say that because chainrings tend to not be super cheap, I don't think I'd risk buying a cheap(er) one with the likelihood that I'd have to go back and buy the OEM one afterall. I'd look for a stock replacement if you're sure that's the problem.

-Jeremy

davidad

https://www.amazon.com/Shimano-9sp-ch.../dp/B0011W6M3U

gsa103

I might be tempted to replace the whole crankset. The large chainring shows some pretty significant wear also. Looks like an excellent time to switch to a double, since that might suit your riding style better.

RoadTire 

I see where you guys are going, so I must have phrased my question incorrectly. Mine is 8 sp, though your posts with 9 sp links get the point across, so thank you. (2010 Talus, 8 speed MC361 on the bike specs, but I could only find Shimano Tech docs for FC-M361) I just put on cheap Shimano twist shifters this winter...

BTW: Anyone have the tech docs for MC361 mountain crankset? Or am I just confused my Shimano numbering and titles?

1st question - middle chainring- : Can I pick up any mountain 32t alu chainring BCD 104 / 64 mm, or need to stick with Shimano? Any other considerations, and do you already have a good source for these? I think the answer is stay with Shimano?

2nd question - crankset- : anyone have the tech docs for MC361 mountain crankset? Is it that much better to replace the whole crankset than just a chainring?

RoadTire 

Agreed double would be better I think, but I just put on new shifters this winter.

TunnelRat81 has a vote for all three chainrings to get the shifting right. I really need to go cheap on this if possible. Once I understand the subtleties of this type of repair, I might be able to intelligently rummage through a couple of the co-ops bins also.

gsa103

Some of the Shimano mountain shifters have a little hidden switch to select 2x or 3x. Could always use the limit screws as well. Just throwing some options out there. Especially since 2 chainrings is probably about equivalent cost to a new crankset.

RoadTire 

A bit off topic: this bike has been fun to work on - rebuilt disc brakes are working great, new cones/bearings in the front hub, replaced the shifters with twist-grips. All has been very successful thank to all the input from the folks here on BF. Cheap, labor intensive repairs have taught me a lot.

RoadTire 

I have cheap Shimano twist shifters. The work great so far - no thumb pain. I suppose I could replace the front shifter ...

fietsbob

Octalink was a passing standard Shimano sold to OEM factories for quite a few years , others adopted it to be compatible .
ISIS was a spline system that at that same time, was outside the Shimano Patented Corral ..

so at this Point You have 2 choices A) Buy 2 new chainrings for the 2 larger sizes , & a new chain
3rd inner looks like you didn't do a lot of Pass Hunting so is still OK.

Or B) a whole New Crankset and BB as the Shimano company went on to start another 'standard' that others had to emulate to get some Market Share..

Square Taper stuff , 110-74 seems to stay pretty Future Proof.

RoadTire 

Any brands of chainrings I should avoid, or conversely, brands that will shift well with the existing small and large chainring? I'm thinking of replacing only the middle right now - $$

I replaced the 8 sp cluster and chain this winter - those were trashed. No surprise the middle chainring skips, but I though I would try it before replacing. The guy I bought the bike from really didn't do any maintenance, like replace the chain, hence the worn out chainring. Ugh.

fietsbob

You want the indexing to work as before I would avoid the low end ones without all the ramps and Pins that aide the shifting..

Maybe You can find New spare steel Shimano replacements . ask Your LBS.

RoadTire 

How about getting a crankset and just using the chainrings? Why? Buy what turns out to be the least expensive:

This is half price at USD $29.99, @ ChainReaction Cycles. Good price, the chainrings have the right tooth count and BDC. I can't use the square taper cranks, so just sell them cheap or keep for spares to use when I replace the BB someday with a square taper. If ever.... I tend not to wear things out very fast. I don't remember if I replaced the BB, but would rather not unless I need to.

Shimano Acera M361 Triple Chainset Square Taper - (I wonder what the C in MC, stands for from the original spec)

Rings: 22/32/42
Spindle Interface Type: Square Taper JIS
Spindle Length: 122.5 mm
Chainring BCD: 104/64
Bolt Pattern: 4-Bolt
Crank-FD Type: Mountain Triple
Chain Compatibility: 7/8-Speed
Pedal Spindle: 9/16"
Crank Intended Use: Mountain

hueyhoolihan

if looking for something that works and to spend as little as possible, i'd just buy the cheapest 104BCD 32t chainring i could find and be done with it.

of course if you can get two more useable chainrings and a bare crank that can be resold on ebay for about the same price, well, there is nothing wrong with that either.

RoadTire 

I enjoy puzzling over compatibly options, if you haven't figured that out months ago. Downright educational.

Just realized if I buy a crankset, gotta make sure the ummm..spider? is the same as I have to fit on the large chainring. Right?

hueyhoolihan

good morning!

right.

note that some triple cranks are designed to mount the large and middle chainring to the spider using the same BCD, and the little chainring on a special mount on the spider. other's mount the little chainring on the middle chainring. sometimes they are riveted to it. there may be other methods that i am not aware of too.

DMF 

I've had to replace a middle chain ring too - mine on 9-speed Ultegra - and had many adventures finding the right one. Shimano uses many different thicknesses, and thickess determines where the teeth lie in relation to the upper and lower rings. A generic ring was actually several millimeters off. I ended up buying the Shimano direct replacement and had no further problems.

I wouldn't change to a double on a mountain bike. The geometry is designed for the triple. Stick with it.

There is a thread around here somewhere where I collected info on various rings. I'll try to find it.

Ah, here it is.

https://www.bikeforums.net/bicycle-me...our-rings.html

Feel free to update it.

fietsbob

Well given bike Assembly Lines in bike Factories is where most of the Components Go .. there is some cost advantage to Buying a new crank with the same Bolt pattern
as the one on your Bike , using the chainrings , then re selling the New crankarms ..

wroomwroomoops

Yay for square taper! But I admit, my second most favourite pedal interface is octalink.

To the OP: I am not quite sure why is octalink even relevant to your question. Just get a suitable BCD 104 chainring, and you're golden. Also, don't be beholden to the chainring being made of aluminium, unless the couple of grams you save are so important to you.

wroomwroomoops

Setups with riveted chainrings are typically very cheap (and bad quality). But they are also usually made of steel, so they'll last quite a lot longer than even aluminium 7075.

RoadTire 

Sorry for the triple quote, but it's a pretty good summary. I might get the square taper 8 sp M361, pull the chainrings and put the matched set on my existing Octalink cranks. Assuming the spiders are the same. Then sell the cranks, or save them for when I do replace the BB, or just get bored with them sitting around.

Square taper M361 seems to be on sale for about $25, and the best price I can find for Octalink is $42. (roughly) Gee, what could go wrong? I either loose any cost advantage with lost shipping / return charges or have to order a square taper BB. Oh, wait. I could try to sell or trade the new Octalink crank arms. Forgot about that.

RoadTire 

Well I just ordered a complete crankset on the 'bay for $35, square taper BB. Hopefully the spider is the same so I can just swap the crank arms. The cost of chainrings + the unknowns of compatibility with my existing setup seems risky, especially for the minimal cost savings. If not .... well maybe a good time to convert to square BB - no idea how much life is left in my BB anyhow.


Rephrase that: "Hopefully the spider is the same so I can just use the chainrings and keep my existing crank arms..."

Tunnelrat81

Good luck with the swap, and don't forget to report here of your success or failure. =)

-Jeremy