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Upgrade: BB, Cassette, chain, chainrings & crankset
#1
Hey all,

I have an old (around the year 2000) Trek 1000 road bike. The chain, chainrings and rear cassette are long overdue for replacement. I want to replace the crankset and bottom bracket while I'm at it too. I know the current drivetrain has 53T/39T chainrings, and an 8 speed 12-24T cassette. the label Shimano SORA appears on front and rear derailuers

My budget is around $300 Australian (roughly the same US), but I'm getting confused with what compatibility issues I might run into, so these are the things I'm trying to clarify:

1. BB & Crankset compatibility: because I'm buying both, get whatever is recommended for the crankset. I am concerned I'll get a BB that won't fit onto the bike: Are there different diameters & thread types to worry about, or have these things changed little recently?

2. Cassette: I know I should get something that physically fits onto the splines of my current hub, though aside from taking it apart (I don't have tools yet) is there any way to tell what I've got? My assumption is that the thread type and diameter for the rear cassette is standard - do they vary? (I will be getting an 8 speed cassette)

3. Chain: as far as I know, I should be fine so long as I get an 8 speed chain; the 10 speed chains have a different thickness to accommodate more gears on the rear hub.

4. Given the bikes age, should I also consider replacing the rear freehub body (I'm not sure if I'm clear here, I mean replace the unit that the cassette fits on to - I don't want to re-lace the rear wheel.)

At the moment, I'm looking at the following parts (if there are significant constraints based on my concerns then this may not be relevant:
Sunrace 12-25 8 speed cassette (does 'fluid drive plus' mean anything useful?) and a 34/50T chainring.

I realise that I'm making the gears a little lower by doing this, though on the flats I rarely max out the gears and I took on my local mountain with mixed results (I got to the top without walking but it wasn't pretty.) So I'd be looking to make this slightly easier.

Any comments on the above would be appreciated. I have attempted my own research, though I noticed statements like 'on older bikes X system is used without first qualifying the date that was written, which was leaving me fairly confused.

Oh, I'm happy to provide photos of my current setup, though I'm not sure what you want to be looking at - let me know if a couple pictures might help.

Cheers!
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#2
A Trek will have standard "english" threading on the BB. There won't be any compatibility issue there. Note that you might be able to just get new chainrings for the crank instead of replacing the whole thing. But cost-wise, sometimes it's cheaper just to buy a new crank anyway.

On the cassette, as long as what you get is "shimano 8 speed compatible" you won't have any problems. Same on chains, you need an "8 speed chain". I prefer SRAM chains to shimano, but there's lots out there.

You might have some slight issues with the front derailleur going down to a 34 in the front. Derailleurs have gear ranges they're designed to work best with and that might be pushing it a little. I suspect it will be fine and it makes sense to get a better gear range for you, but FYI.

Freehub bodies typically last for decades without a problem so I wouldn't replace it for no reason. But if it's making weird sounds or skips once in a while, then it probably wouldn't be a bad idea. If your rear derailleur has a lot of side to side play or you have trouble getting the shifting adjusted properly, it might make sense to swap that out. But again, I've seen tons of derailleurs last way longer that 10 years so not "required".

Fresh cables and housing are probably a good idea if the old ones are showing any rust, cracks, splitting, etc. Beyond that, my standard "upgrade advice" is "good tires and brakes pads". They have a pretty good bang for your buck ratio in the upgrade game and people tend to put up with old ones that don't work well because they degrade slowly and you don't notice how bad they are until you put something fresh on.
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