Monoborracho

I have a chance to buy an older Trek 520. After checking the serial # and the vintage Trek site it appears to be a 94 model. It also has other small numbers on the bottom bracket...then larger #'s that say 520 21. The bike component group is Shimano LX. It has a 7 speed LX free hub wheel, and 135mm dropouts on the frame. I like it that it has Deore LX trekking chainrings with 175mm crank arms.

Is it fair to assume this is a 21 inch model?

Would this 7 speed freehub accept 8 speed or 9 speed cogs, assuming I change the shifters? Or is this one of those older 7 speed Shimano freehubs that only accept 7 speed?

Is there a way to tell more about the freehub other than just trying an 8 speed cassette?

knobster

If I'm not mistaken, I do believe you can change the cassette without any problems. I've got a 93 model with the 7 speed stuff and I really like it. I'd say get it and see if you need to change it. Chances are you won't. I think I paid like $200 for mine.

Monoborracho

Thanks, I will.

Svr

Can you see a model number on the hub label? FH-M565 is the eight speed version of that vintage LX group.

Michel Gagnon

I think you should visit two pages by Sheldon Brown:
– this page about cassettes;
– this page about the evolution of dura-ace and other systems.

Assuming you have a Hyperglide freehub body (which I think means 1987 or 1989 and beyond), all freehub bodies may be fitted with 7, 8, 9 or 10-speed cassettes, but... the 7-speed freehub is narrower than the 8/9/10 speed freehub.

So what could you do?

1. Leave it as is.

2. Buy a 9-speed cassette, but keep 8 or the 9 cogs. If I were to do that, I would buy a "low-end" cassette, which is equally durable, but slightly heavier because it's made of individual cogs. I would then remove the rivets and keep the first seven and the last cog. For instance, from:
11-13-15-17-20-23-26-30-34, I would discard the 30 and keep the 34 as a bailout.

3. Lenghten the axle, buy a new, longer freehub body and install a 9-speed cassette. You are likely to have to spread the frame a bit for that.


Two other possibilities

If the only reason you want to change your gears is to get closer ratios, you might be able to do that with a custom 7-speed cassette. Buy two 7-speed cassettes (or one 7-speed and one 8-speed) with the cogs you want, select ratios that avoid duplicates and that give you closest ratios where you want them, and cobble up your own cassette that way.

And if you want to change your drivetrain because your shifters are broken, you could buy new 9-speed shifters and use them with your 7-speed drivetrain by using the alternate cable routing shown on the Dura Ace page.

Monoborracho

I didn't even think to look for a number (duhhhh) when I had the cassette off. I've put it all back together again. Where would the number be located?

Svr

It might be on the decal wrapped around the hub shell. If you've removed the cassette and didn't notice a spacer behind it, it's safe to say you've got a seven speed hub.

jjciiijs

Just my thoughts, but I also have the 520 7 speed and it is the smoothest, quietest and most easily adjustable bike of all because the 7 speed has allot of room for "off adjustment" before you have any problems or noise. I run bar end shifter and tour with it. Great bike but not lite.

Try leaving it for awhile.

Monoborracho

I hadn't thought of that. There was no spacer.

I think I've about decided to just check the hubs, spokes, and rims real good and try the 7 speed for a the summer then decide what I want to do.

wrongdave

I have a 94 trek 520 and it continues to be the smoothest shifting bike I own. I've never even considered "upgrading" it to an 8 or 9 speed. Everything is still original on mine except for the chain, cassette, and rear deraileur (and tires of course). If it ain't broke ...