996

As the title states, I have an older Shimano 600 tri color 8 speed rear hub. I have 7 speed group laying around and don't want to mess with spacers too much. Would it be possible to swap out the current 8 speed hub body for a 7 speed hub body (also Shimano) that I have laying around from that era?

Thanks so much.

Bill Kapaun

It's one 4.5mm spacer, so that's not a big deal.
A 7 speed "should" swap.
If your current FH is removable with a 10mm hex wrench......

You'll want to make up the difference in spacing between the 2 FH bodies by adding an equal amount to the NDS. Somewhere around 3-4mm.
Dish the wheel to center. This is EASILY done. Just tighten the NDS spokes evenly until you get it. probably less than 1 turn, so go in smaller steps.
This step results in a more symmetrical, stronger wheel.

FastJake

It's a LOT easier to just toss a spacer on before installing the cassette. What kind of shifters do you have? If they are downtube, you can run a 7-speed cassette "plus one" extra cog in the back. The shifter will accommodate this if you set the derailer correctly.

With that said, if you want a slightly stronger rear wheel, it's easy to swap bodies. It's best if you have the right-side cone/washer/locknut that goes with the body because they're not all the same and might not play well if you try to mix and match.

996

Got it. thank you for the responses. I have down tube 7 speed shifters (older Shimano ones). The hub isn't laced to a wheel, so I don't think i have to worry about dishing the wheel properly after a swap.

Probably easier just throwing a spacer on OR running an 8 speed cassette and seeing if the 7 speed downtube shifter can work with this... below is a pic of the downtube shifters I have. Also the derailleur. https://imgur.com/a/9grA0UQ

TY.

FastJake

Just keep in mind that you won't be able to remove the body until the hub is built into a wheel. You'll need the leverage of the wheel to loosen the 10mm Allen bolt. Unless you stick it in a vise or something, but it's easy to put major gouges in it that way.

An 8-speed cassette may work ok but the spacing is slightly different and the indexing might run rough at the ends of the cassette. If you want perfect shifting, just get a 7-speed cassette and add an extra cog at the back. Or space an 8-speed cassette with 7-speed spacers. It's best to measure the spacers and make sure the extra thickness is coming from them and not the cogs. But mixing Shimano/Shimano is usually safe.

996

Appreciate the input. Noted and will probably stick with an 8 speed and maybe find some new shifters which shouldn't be too hard.

Thanks!

70sSanO

Just to back up a bit. Does your 8 speed hub fit your bike? Going from 7 speed to 8 speed requires a dropout width of 130mm. Depending on the bike, you can probably spread the frame (rear triangle). This typically not a big deal.

Bit all honesty, messing with $5 4.5mm spacer is going to so much easier than messing with finding 8 speed downtube shifters. Sunrace are pure junk, for $35 you can try Microshift, $50+ will get you a Shimano, and $100 will get you a set of tri-color shifters.

It’s your call.

John

FastJake

8-speed downtube shifters are somewhat rare but still find-able. By the time 8-speed came around most bikes were switching to STI (brifters.)

One of the other workarounds is probably easier, but do what you wish.

Bill Kapaun

If you're going to get new shifters, it'd be an opportune time to make the jump to 9 speed. More cog combinations available.
Shifters & cassette are only slightly more than 8 speed.
You will need a 9 speed chain.

Retro Grouch 

If it was my bike, and I had a 7-speed free hub body, and I wanted to keep the bike 7-speed for any reason, I'd swap out the free hub bodies and readjust the axle spacers and dish. It just looks more elegant.