Arthur Peabody

I need new chainrings (sigh!) for my Shimano Deore triple: 5-arm, 110 & 74 mm. Listings specify gear numbers, most for 10-11, which means a thinner chain, perhaps thinner chainrings? than my 8.

cyccommute 

Yes. The 10 speed ones are moderately thinner but that shouldn’t cause any problems. Chainwheels, in general, are more forgiving about speed anyway. I’m using cranksets from the 90s (9 speeds) with 10 speed rear drivetrains and haven’t have any problems. I have a 10 speed crank on my wife’s bike with a 9 speed drivetrain and, again, no problems.

70sSanO

Yes. My wife is running a 10 speed crank with 8 speed cassette. Because the crank has 10 speed chain ring spacing, I’m running a 9 speed chain.

In your case, you can run an 8 speed chain.

John

Arthur Peabody

Thanks. I shopped and see that 8-speed is going out of style. SRAM makes no chainrings that thin; Shimano makes none for 5-arm cranks. I found 1 Shimano for a 9. Even worse is replacing the 24-tooth 74 mm - I find only 'vintage' Suginos on eBay, none at Jenson or other bicycle vendors. Some people are selling used Shimanos. I'll probably have to get new crank eventually.
8-speed chainrings are 3/32"; >8 chainrings are 5/64"; if they're made from the same material they'll wear out more quickly.

70sSanO

104mm are harder to find, but this might help for your 24t...

https://www.ebay.com/itm/Vintage-New...53.m1438.l2649

John

Edit Added: I have 2 older mtb's and I am running 24/34 (74/110bcd) x 8. I use the Shimano steel rings above and Sugino aluminum 9 speed 34t rings. They have held up well. I have bought extra for future replacements for me or if my kids want the bikes one day.

John

cyccommute 

Check Veulta for chain rings. Lots of different bolt circle diameters.

Arthur Peabody

Whoops! I typoed - I meant 110.

My point is that 'vintage' may mean not-made-anymore, thus unlikely to be found next time.

Thanks. I think they're 5/64"; the 74mm is OOS.

Eggman84

Differences in thickness and spacing of chain rings is trivial in my opinion. The big change was the addition of ramps and pins starting with 9 speed. Why was this necessary. Two reasons. First with indexed front shifting, there was no ability to "overshift" to help the chain onto the larger chainring. Second, starting with I believe 9 speed chains, the pins no longer protrude beyond the outer chain plate; the protruding pins of wider chains snagged the larger chainring, helping to lift the chain onto the ring. Thus ramps and pins entered the picture along with "matched sets".

As to chainrings. Spécialités TA from France makes some of the best alloy110 BCD rings available; inner (for double) /middle (for triples) are available from 33 to 42 teeth and outer from 40 to 54 in the even #s plus a 53. For 74 BCD , they make a 24, 26, and 28. Many others make these small 74 BCD chainrings. The TA chain rings are available from Harris Cyclery as well as Peter White Cycles. Peter has a good discussion about chainrings as well..

vane171

Thanks for explaining that it was the indexed shifting which required those intricately shaped ramps on chainrings as well as those pins that really look almost as just rivets with a lip left on the inside of them where the ramp channels are. I never quite thought of it this far, to connect it with the indexed shifting. I thought it was just to improve chain transition to big ring, but not being able to overshift with indexed shifting makes even more sense.

Arthur Peabody

I saw those Shimanos. I've been dubious about 'new (other)'. Maybe this guy means unused but old style. Will the steel Shimano or alloy Sugino last longer?

delbiker1 

I have various Vuelta chainrings in different BCD and tooth count. They are aluminum, work well, and appear to be durable. I believe it is the SE Plus rings that have ramps and pins. I have a couple of Sugino rings made of steel. They are considerably more costly, have fewer options size wise, and are not ramped or pinned. The steel probably would last longer, but I am not sure the extra cost is worth that. The Vuelta can be found on Amazon, Ebay, Performance bike, and probably others.

hokiefyd 

Unless I'm misunderstanding the shift aids, they definitely pre-dated 9-speed drivetrains. 3x7 systems from the early '90s included the ramps and pins on the chain rings (Shimano seemed to prefer "ramps" or twisted bits of the ring, while Sugino seemed to prefer pins). This may not be the case for road, but's definitely the case with mountain groups. Also -- indexed flat bar shifters do allow you to "overshift" the front derailleur during a shift. You can continue to push the lower trigger lever through and beyond the click -- it'll continue to move the front derailleur. After your shift is complete (which is pretty much instantaneous if your pedaling cadence is reasonable), the derailleur will "fall back" to the indexed point when you release the lever. You can do the same with grip shifters (overshift the front, and then release to the indexed point). STI shifters may not allow for overshifting like this, but flat bar shifters do pretty well with this.

70sSanO

For my mtb’s on sub-30t I’ve used steel rings and I can’t imagine aluminum lasting longer. My 24 is my up ring and the 34 is my down/flat ring.

New other is generally without original packaging, sometimes scratches from sitting in a bin, and sometimes a new take-off.

I don’t know the year of your crank. I think M730 came out in the late 80’s and 4 arm (94/58) cranks in mid to late 90’s. I don’t know how long STX, Alivio, etc. went on as 5 arm 110/74. Needless to say, those Shimano SG-C chainrings might be 20/30 years old. Which means it is 6/7/8/(9?) speed compatible. When they are gone, that’s it.

John