trail_monkey

I just got my rear wheel built this afternoon for my 85 Panasonic. I am going from the stock 126 mm freewheel rear hub to a 130 spaced cassette hub. I ordered all my stuff and mistakenly thought I had an original 8 speed rear hub and it turns out it was a 7 speed cassette hub. The hub in question is a Shimano Exage rear hub (part number FH-HG50) from an early Trek road bike maybe late 80s early 90s vintage? My first reaction was just to get online and order an 8 speed Shimano rear freehub body and bolt it on. Then as I talked to more "experts" I was being led to be that it wasn't such an easy task. So I called Shimano directly and talked to a nice young fella who himself has restored vintage bikes. I gave him the part number off of the hub and he said it would be difficult to find a rear freehub body for that. he explained that the splines that engage the body that are machined into the hub itself are not the same from hub to hub. Bummer. I thought the interface would be universal on all cup and cone shimano hubs. I am at a loss. The wheel is finished......Trued,tensioned,stress relieved, taped and tire and tube mounted with no cassette. Should I just send back the 8 speed cassette to where I bought it and buy a 7 speed cassette? Is there hope for finding a compatible 8 speed freehub body for this hub? Google searching online gives mixed opinions. Some people say "Yeah we used to do that all the time at the shop". Others say "No it won't work". If I would have know all this was going to come about I would have just built my new wheels using my original hub but I hate to back out now that it is done.

jimmuller 

drop a PM to pastorbobnlnh

TenGrainBread 

I would just use a 7 speed cassette. Cassettes are cheap and there's not much difference between 7sp and 8sp gearing-wise.

The only reason I would think of trying to change the freehub body to 8 speed is if I REALLY REALLY wanted to use some indexed shifters that only work with 8 speed.

trail_monkey

If I stick with 7 speed, did I gain anything by going to a different hub? Stronger axle? What concerns me is parts replacement down the road. If a freehub blows up (probably won't) I doubt I can find a replacement hub as easy as I can buy a new 7 speed freewheel. But I don't feel like wasting my money anymore so I will probably end up exchanging my 8 speed cassette for my 7 speed. Just a bummer is all.

agmetal

You can always put a spacer behind a 7-speed cassette on an 8+ speed fh body

EDIT: Never mind, I mis-read what you said

nlerner

I've changed 7-speed freehubs to 8-speed free hubs, and I believe your Exage hub is an eligible candidate. If you haven't already, see Sheldon Brown's instructions. The issue I encountered is that I needed a longer axle or to re-space/re-dish so that chain when on the smallest cog would clear the inside of the dropout.

Chrome Molly

Like he just said

If you have to re-dish the wheel then I would just stick with 7 speed. With a UG cassette going 8 of 9 on 7 would probably not be easy but possible with the right spacers.

trail_monkey

Winner winner...lol. I found this..https://www.modernbike.com/shimano-h...3-34t-cassette

Maybe this is a better way to go. I didn't realize a 7 speed cassette came in these kind of ratios.

CliffordK

Take an 8mm (or was it 10mm?) Allen wrench and pop the freehub off.

There are a lot of similarities between older Shimano freehub bodies, up to 8/9/10. The 11s are different

trail_monkey

Yeah I am at a dilema. I just noticed that the freehub body has a tiny bit of play. Not much but maybe a mm or so. If it is going bad then I may be screwed in the future trying to find a replacement. If however I used my original hub and the freehweel crapped out, I can find replacements everywhere dirt cheap. I have a 135 spaced deore mtb 7 speed freehub in the shop from a 90s MTB. The freehub looks the same externally but I have no idea if the race spacing is the same internally etc. Maybe only one way to find out.

trail_monkey

Edit I just went out and swapped the 7 speed freehub Body from the deore rear hub to the Exage and it was a perfect match plus it has less free play. I will keep the original for a spare should I ever need it. I never thought there would be so many discrepancies between shimano hubs. Damm!

Jeff Wills

I've played with swapping 7 and 8-speed freehub bodies on various Shimano hubs. They aren't all cross-compatible. In particular, bodies from "road" and cheaper mountain hubs have less space from the last cog to the surface where the cassette body meets the hub body. On more expensive "mountain" hubs the body is recessed into the hub a bit more, sealing this area a little better.

Good to hear your swap went well.

trail_monkey

I didn't measure anything. The freehub looks the same as the original. It fit on the hub the same. I spins fine. After pre loading the bearings the axle is the same spacing. The only difference I can see is that it does not have the external threads on the hub splines so it is a newer hyperglide. This freehub is off of a mid 90s Deore rear mountain bike hub that was a 7 speed cassette. Is there anything I should inspect closer that I might have overlooked?

rccardr 

Yes- Are the two freehubs the same size (length)? If so, you just swapped a 7 speed UG FH for a 7 speed HG freehub. I only say this because you mention that the Deore FH was also from a 7 speed. Could have been a wider 8-9-10 speed length with a 4.5mm spacer behind the cassette, but I;ve also owned 7 speed HG freehubs. Just measure and see (shorter ones are around 31mm, longer are around 34-35mm), or try to put an 8-9-10 speed cassette on it to see if it's long enough.

trail_monkey

Yes I held them together and they are the same length. Both freehub bodies have a "built" in shim at the back. In other words the spline machining stops short of the rear. And my original freehub body had the master spline (one spline wider than the rest), just like the Deore freehub body I used so they are both HG freehubs according to the Sheldon site anyways. The first HG bodies used these threads so that you could still use UG cassettes. I personally have never seen one of these early cassettes so I am unfamiliar with the treading on the outer cogs. I am just going off of what I read on Sheldons page.

rccardr 

Ah. Well then it is likely that almost any 90's road freehub would fit your hub shell and give you the 8-9-10 speed HG cassette spacing you desire.

trail_monkey

I am thinking that is so......But after doing research it seems as all I gain by going to an 8 speed cassette is the 11 tooth outer cog. My bikes soon to be running a Sakae 52-40 front crankset. I don't have the legs for any more than a 13 or 14 small cog with a 52 front ring so there is no need. The rest of the cassette should be similar. I might as well just get a 7 speed cassette.

Pompiere

Not exactly the same issue, but when I found myself with a 8 speed wheel and 7 speed shifters, I adjusted the high stop on the derailleur to lock out the 11 tooth cog. Shifts fine on the remaining 7 cogs, and with a 53 chain wheel, I don't need the 11 cog.

Falcon3

My 105 hub of the same era was an easy swap for an 8speed free hub. Cost about $10. Can you remove your freehib and post some pics of what it looks like?

trail_monkey

It looks like this one even the splines on the back are identical.Shimano SLX Free Hub Body > Components > Wheel Parts > Freehub Bodies | Jenson USA

rccardr 

Just remember that with a cassette you're only limited by your imagination and a few restrictions. You can have an 11, 12, or 13, small cog, and up to a 34 large cog, depending on what your RD will play with. So if you spend a lot of time in the flats, an 11-12-13-14-15 bottem set of cogs would be very handy. Ride in the hills a bunch? Try a 30-27-24-21-19 big end, since that's where you'll be a lot of the time. Somewhere in the middle means a mid section of 16-18-18-19 will give you a lot of choice on a windy day. You can usually find cogs at one end or the other of the spectrum either used or at the coop.