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Non-shifting 32-tooth chainring for Shimano STX crankset--Any suggestions?

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Non-shifting 32-tooth chainring for Shimano STX crankset--Any suggestions?

Old 07-04-10, 08:59 PM
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Jowdy
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Non-shifting 32-tooth chainring for Shimano STX crankset--Any suggestions?

Howdy,

I'm doing a little project on an old mountain bike, and want to install a 32-tooth chain ring on the crank, nothing else. (And I'll be using four or five sprockets on the rear cassette.)

Of course, I don't want the chain to be inclined to slide off as I'm shifting the rear gears, so I'm wondering if anyone has a recommendation for such a chainring. I've read that most compatible chainrings (like Shimano's something-glide style) are machined to allow the chain to shift easily off the chain ring when changing gears.

So, to distill: What's a good non-shifting 32-tooth chainring compatible with the five-bold pattern of my Shimano STX crankset?

Thanks for your help.

Jowdy
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Old 07-05-10, 01:02 AM
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Do you know what the bolt circle diameter (BCD) of the crank is, specifically for the middle chainring? See here: https://sheldonbrown.com/harris/chainrings.html

I'm guessing 110mm. In that case, the smallest chainring that will work is 33T, which is rare (https://www.sheldonbrown.com/harris/chainrings/110.html). Should be able to easily find a single-speed 34T chainring, such as https://www.universalcycles.com/shopp...s.php?id=16021 Just make sure it is for 3/32" NOT 1/8" chain.

If the middle and outer chainring positions are 110 BCD, the inner chainring spot will likely take 74mm BCD, which can take a 32T. You'd probably want to get a longer bottom bracket so that the new chainline of the inner chainring can be similar to the original chainlline of the middle chainring.

If you do have a 110mm BCD crank, I suggest just using a 34T and adjusting the size of your cogs to accommodate the slightly higher gearing.
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Old 07-05-10, 02:29 AM
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There were some older STX cranks that had unique chainrings. Without a model number or photo, it is difficult to give definitive advice.
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Old 07-05-10, 02:51 AM
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A non-ramped chainring like the one Salsa makes should work out for you. As far as I know STX cranks used a 94/58 bolt pattern.

https://www.universalcycles.com/shopp...7&category=649
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Old 07-06-10, 12:35 AM
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All,

Big thanks for the feedback; this all points me in good directions.

And, Turkey, thanks for the brief breakdown of complexities to consider. It helps as I slowly gain an applicable vocabulary for this stuff.

j
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Old 07-06-10, 10:57 AM
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Originally Posted by Ingleside View Post
As far as I know STX cranks used a 94/58 bolt pattern.
+1
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Old 07-06-10, 01:19 PM
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I also recall STX or STX-RC having an odd pattern... maybe the right BCD for some standard size, but standard rings still didn't fit very well.
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Old 07-06-10, 01:23 PM
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If you go with a Surly, be sure to add a bash guard. If you're not going to add a bash guard, Surly isn't a good choice, look for a beefy aluminum chainring.
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