Is a 90s Trek compatible with a new drivetrain from today?
 

I have a old 1995 trek Mountain track 850 that has a completely worn out drivetrain beyond repair. I want to upgrade the whole drivetrain to a 36t SHIMANO ALTUS M2000 2x9 speed groupset.
Link- https://www.aliexpress.com/item/1005...74637964%21rec
Will this work? Is there a better way?

Yep, that will work as long as you have a freehub body that's not 7 speed only. Also, the listing is vague on what shell width the BB they're including is, but it's a safe bet it will be 73mm and match your old frame, just know that you may need to source a different one if that doesn't match.

That said, considering this is really cheap on Aliexpress, there's a good chance that what you'll actually get in the box is cheap copies or falsely badged copies of the Shimano original parts. But frankly, at this price/quality point does that even matter? Up to you to decide. The alternative that would be safer if you care would be to purchase parts through your local bike shop.

I have no way of going to a bike shop to buy the parts or for help because i live out bush. I do not have any verniers to get any measurements unfortunately. Do you know anywhere else online i can get the same groupset? I agree that buying of aliexpress is sketchy but it was the only website i could find that offered this groupset or anything similar.

I see you're in Australia. I don't know if any US bike shop with a good online presence like Tree Fort Bikes ship out there and even then cost might be prohibitive. Perhaps try calling the popular bike shop in the nearest major city and get their advice?

Good point.

OP: if your current drivetrain is Shimano 7-speed rear, you want to check this. Quickest way to confirm is to pull the rear cassette and see if there's a spacer(s) of about 4 mm or so behind it. Or you could measure the freehub body length - if it's about 31mm it's 7-speed only, while if it's around 35mm it's 8/9/10 speed (11-speed is longer, but didn't exist in 1995).

If the OPs bike matches the 1995 Trek catalog, it will be a equipped with a 3x7 drivetrain (Shimano Alivio/STX) as OEM. As per Hondo6 above, it would be a good idea to confirm the size of the freehub before making a purchase.

If the OP can post some pictures of the bike, especially the rear hub and cassette with spacing and any part numbers visible, I'm sure someone here will be able to assist with sorting out what's compatible.

That's a nice enough frameset that putting some money into a new drivetrain can be worthwhile. Shimano's Altus line looks like it has 7-sp offerings as well if you do have the smaller freehub.

While I have no personal experience, I hear that Microshift components are of good quality and it looks like they have a 7-sp MTB group ("Mezzo") that may be worth tracking down for comparison shopping.


https://cimg1.ibsrv.net/gimg/bikefor...7263dbd23a.jpg

Did some further checking.

The Trek doc above says the hubs are "Shimano Acera X Parallex". The only "Acera X Parallex" rear hub I could find reference to was the FH-M290. All versions of that rear hub seem to be 7-speed HG hubs only.

OP: can you find a model number on your existing rear hub? For that model, I think the model number was on a sticker on the hub barrel.

You can remove one cog and spacer from the cassette giving you 8 speeds with 9 speed spacing, this will fit a 7 speed freehub body. If you remove a cog from the center range there may be a down shift that isn’t as quick or smooth as the others but it will work. Shimano cassettes are usually held together with riveted pins, grinding off the heads from the back of the large cog will allow you to disassemble the unit.

See Sheldon Brown article:
https://www.sheldonbrown.com/k7.html#bodycompat

Cheap digital calipers can be had on Amazon or other sources. The more you need to do stuff yourself, the more you need basic and accurate measurement. devices and tools.


Here in the USA, Amazon has a set of digital calipers for $8.19. I would expect the price to be higher in Australia but my guess they will have something similar.

Not having them is understandable. Not getting them is not a sustainable plan.

Very nice photo and great bike to maintain! Good luck with your work.

From what I can see it will work. My concerns are:

There is no specified clamp diameter for the front deraileur, you may need a spacer shim. The pictures appear to show a dual pull unit but I am not certain of this, the description provides no answer.

The bottom bracket is listed as 68 and 73mm shell compatible but does not mention a spacer, if your shell is a 68 you’ll need a 2.5 or 3mm spacer for the drive side.

You most certainly have a 7 speed freehub body but can make the 9 speed cassette work as stated in my earlier post.

Have fun and be sure to post pictures.

Not my bike; it's the OPs. But I agree that it's a very nice bike.

I'm pretty sure the OP agrees too. :)