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Discussion Starter · #1 ·
Hello fellow bike enthusiats.

I have a 1990s Trek zx6000 Easton aluminim bonded MTB. The bike is in very good shape but the chainring teeth are worn very badly and need replaced.

The current crankset is a Sugino Impel 175mm connecting to a square taper BB. The rings are 42-34-24. This of course is a 8 speed.

Now my problem. The only crankset I can find that appears to match all these specs is a Shamino Tourney series. Which I can find in 175mm, 42-34-24 square taper.

There are some different 8 and even some 9 speed cranksets that are of better quality, but are in different chainring teeth counts.

I could replace more stuff, but really everything but the chainrings are in great shape. Would prefer to leave it as original as possible while still having a daily rider. Its sooooo light. :)

I haven't done bike builds (as my post likely readily shows) but I am mechanically inclined.

Any suggestions for a solution to replacing the crankset with a decent alternative w/o overhauling the entire drivechain?

Thank you,

Salty
 

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U sayin' Bolt ?
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You don't have to be married to 8 speed 42-34-24 rings, if you are willing to adjust your front derailleur. You will probably have to tweak it a little bit anyway with a new crank.
 

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Discussion Starter · #3 ·
Thank you for the reply :)

I can adjust and like you mentioned adjustment is likely to be required regardless. I admit, I am a novice here. I do think there is a limit as to what will work reliably.

I am willing to spend around 100 bucks or so, its just that there is so many choicea not sure which would work well but be of good quality.
 

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You can use different sized chainrings, maybe even think about going 2x.

Also, if the teeth are that worn you'll most likely have to replace the chain and cassette too
 

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Discussion Starter · #5 ·
Chain was replaced a while back should be ok. Rear cassette looks pretty good, teeth are still in good shape and are nicely uniform. But, would certainly like to hear more. What would going to a 2x buy me?

Sorry I am a bike mechanic noob. :)
 

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Chain was replaced a while back should be ok. Rear cassette looks pretty good, teeth are still in good shape and are nicely uniform. But, would certainly like to hear more. What would going to a 2x buy me?

Sorry I am a bike mechanic noob. :)
You may be alright with the chain and cassette then, it's just been my experience that replacing a drivetrain part on old bikes often opens a can of worms. You'll know for sure when you put the new crankset on and take it for a ride.

As far as 2x I just like it better but that's down to personal preference, I like 1x even better yet.
 

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Discussion Starter · #7 ·
Is the sqaure taper BB my most limiting factor here?

As far as options, looks like Shimano has a couple, SRAM S600 and SR Suntour which I never heard of. Sugino has an option as well but at 150 its a bit pricey but doable.

Sugino XD600 Cranksets
https://www.treefortbikes.com/Sugino-XD600-26-36-46-Triple-Crankset

SRAM s600
https://www.universalcycles.com/sho...MIyozMu56z4gIVG57ACh2b1QsjEAQYASABEgLnnvD_BwE

Shimano
Acera
https://blueskycycling.com/products...MI6J_06J6z4gIVmbfACh15dAAIEAQYFCABEgJwovD_BwE
Altus
https://www.jensonusa.com/Shimano-A...MI6J_06J6z4gIVmbfACh15dAAIEAQYDyABEgJe0vD_BwE

SR Suntour
https://www.amazon.com/Suntour-Cran...ocphy=1016367&hvtargid=pla-623266475687&psc=1

Not a lot of choices tbh. :/
 

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Also keep in mind that square taper cranks have different profiles that require different spindle lengths so depending on which one you get you may need a new bb as well.
 

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Is your chain and cassette still OK? Rule of thumb is 3 chains last 1 cassette and 3 cassettes 1 chainrings. So at chainring change time you change chain and cassette. If so, this may he the time to upgrade to 1x11 or similar.

I also would look into external nearing BB. Much better choice of good cranks. Your BB may be worn anyway. A Deore BB cost $15 and will allow 24mm spindle crank, which are plenty and reasonable.

Check bike24.de or bikediscoun.de
 

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Discussion Starter · #12 ·
Thank you for the reply.

I am not opposed to replacing chain, BB, crank and cassette. I dont want to replace derailers though.

For the rear cassette, should I remove to check the spline/hub length to see if I can fit a 9 or 10?

If I do chage out to say...a 9 and use a 2x would I need new derailers?
 

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Any change in number of speeds requires new shifter and derailleur.

Honestly. Bite the bullet once and be happy. 2x10 or 1x11 is much better. Don't go to 9 speed... if you make the effort to upgrade, make it count.

Edit: external Deore BB is $8 if you order from the German stores I listed above. Really no reason to stay with the old one.
 

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You have an old bike and it's not worth much but still in good working order. The first question I would ask is how does the current 8spd gearing work for me (not the condition, the actual gearing). If you are good with it, why spend the extra $ to change to 9 or 10 speed derailleurs/shifters/new cables, etc?

As mentioned, usually it's better to replace entire setup (cassette, chain, chain rings) because one new component may not match up with any existing wear on the others. Sounds like your cassette/chain are fairly new so it's worth rolling the dice to try new chain rings and see how it goes. If you still have shifting issues, then you could go after cassette/chain to be 100% new.

There's stuff out there for 8spd...just need to keep looking around and be sure of the current dimensions of your existing components.
 

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Discussion Starter · #16 ·
If the chainrings are all you want to replace, why not just replace them rather than the entire crankset?
Great question and thank you for the reply. The local bike shop said the BCD and pattern was no longer available. Else, I would definitely just replace the rings. I took their word for it, and have not really investigated this route.

Yeah, I really don't want to convert to a completely different drivetrain / derailer / shifter solution. Id prefer to keep it somewhat original. Its not worth much but its a pretty cool bike and like i said, its very light.
 

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Discussion Starter · #17 ·
You have an old bike and it's not worth much but still in good working order. The first question I would ask is how does the current 8spd gearing work for me (not the condition, the actual gearing). If you are good with it, why spend the extra $ to change to 9 or 10 speed derailleurs/shifters/new cables, etc?

As mentioned, usually it's better to replace entire setup (cassette, chain, chain rings) because one new component may not match up with any existing wear on the others. Sounds like your cassette/chain are fairly new so it's worth rolling the dice to try new chain rings and see how it goes. If you still have shifting issues, then you could go after cassette/chain to be 100% new.

There's stuff out there for 8spd...just need to keep looking around and be sure of the current dimensions of your existing components.
The gearing works fine for me TBH. Never had an issue with either more strenuous climbs nor just open pavement.

Agree on the chainrings and will take a look at that and post back what I find.

I appreciate everyone's comments, as you can tell I am not very experienced in bike builds, just riding them :).
 

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Rather than replacing the whole crankset, you could just replace the chainrings. Replacement chainrings for that crankset are still available from several manufacturers. If there is a used bike shop near you or a bicycle co-op, they likely have lightly used rings for that setup at inexpensive prices.

Here is a link to replacement chainrings that should fit your current cranks and setup. Many sizes are available:
https://www.jensonusa.com/Sugino-Standard-Chainring-Silver-110mm-36-Tooth
 

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U sayin' Bolt ?
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Is it the original BB that came with the bike? How many rotations will it spin freely, when you give the cranks a hard spin? Can you detect any play?

If you want to spend $100 and get something nice, I would say converting to an external BB is the way to go. $100 is a competitive price point for nearly every manufacturer for that, now standard, style of crank.

Otherwise, if your square BB is in good shape, you already have an axle. Get that Suntour for $25, and have $75 to put towards some big pedals, nice fat grips, high end tires and/or a saddle. Upgrading contact points is far and away the best bang for your buck.

That suntour isn't light, but it has forged arms and steel rings, so it should last. Suntour is an established value oriented brand.

https://www.summitbicycles.com/product/sr-suntour-xcm-t-crankset-299843-1.htm?variations=213501,213411,213439,214839&gclid=CjwKCAjwiZnnBRBQEiwAcWKfYo_R76z9fTrz2CsSu-40p-xwl6egOdQOLKBcwflcMok0IpImait06RoCDZ4QAvD_BwE
 

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You don't need to stick to 8-speed bits, a 9-speed crank-set will work just fine.

You don't need to stick to square taper. You can use any BB that fits your frame and the chain-set.

You don't need the tooth count to be exactly the same. The big ring is the one to watch. Most front derailleurs will work happily with rings that are a little bigger or smaller, a couple of teeth either way should be fine.

Going to X2 rather than x3 will save you pretty much nothing. You still need the same part count, you're just loosing the granny gear so steep hills will be much harder. Yes, you can claw that climbing ability back but you'd have to change more things to do it. Why bother.
 
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