trustnoone

Good day,

I have a 1992 Specialized Allez with a 7 sp 105 hub. Does anyone know if this is an easy conversion to an 8 sp? I assume a 9+ will need a new hub if not a new frame.

Thanks,

M

JiveTurkey

First, is the 7-speed in the back a freewheel or cassette?
See here for difference: https://sheldonbrown.com/gloss_ca-g.html#cassette

If it is a cassette and there is a 4.5 mm spacer behind the cogs, there's a good chance the hub can be used for an 8, 9 or 10-speed cassette. If not, you'll need a new hub (though maybe you can just change out the freehub mechanism???) as well as cassette.
Or, you can try this (look toward the borrom for "8 Of 9 On 7"): https://sheldonbrown.com/k7.html

If you go the conventional route and use an 8, 9 or 10-speed cassette, make sure your frame can handle it. It must be either 1) 130 mm spaced between rear dropouts or 2) Steel and it can be strtched (do not stretch other materials).

A lot of this info is on SheldonBrown.com, take a look.

If you can use your old hub, all you need is: shifters, cassette, chain and likely a new front derailleur.

Doctor Who

I did this to my Paramount PDG Series 3, which came stock with 7-speed Shimano RX100. I replaced the freehub on the original RX100 hub with an 8-speed unit, and then added a 12-tooth cog. The downtube shifter was replaced with a Ultegra 600 brake/shift-lever. Nothing else was done and it works pretty well.

the beef

Seven's the crappy number of indexed drivetrains. It's eight, nine, and ten speeds which are in general more intercompatible. You'll most likely need a new freehub body.

The old 7 spd derailleur should work fine; derailleurs generally are not too speed-specific. You'll do good to invest in a narrower chain, though - trust me.

Treefox

Did something similar with my ca. 1992 Peugeot, which was seven speed RX100. How have 9 speed Tiagra shifters, 105 RD, FD, Cassette, & Chain. Needed a new rear wheel so I just got a pair of 550s cheap. Also new BB because it was getting a bit rough. Still have the same cranks and brakes.

Doctor Who

No, you don't need a new hub, just so long as you can replace the 7-speed freehub assembly on the hub with an 8-speed unit. The part cost me $24 or so.

And I'm using the original 7-speed chain on the 8-speed system, which is correct. The only difference between a 7 and 8-speed freehub is that the 8-speed unit gives room for the smallest cog.

vpiuva

Changing out the freehub body from 7s to an 8/9/10 is easy. Requires you to remove the axle and the use of a 10mm allen wrench. Clean and repack your hub bearings while you're in there - knock out 2 needs at one time.

Freehub bodies cost about $30, but you can often find cheap new hubs on eBay for even less, & the bodies are the same. I've gone that route, swapped the bodies, resold the cheap hub as a 7 speed & recouped most of the $.

Brian Ratliff

If you have a true 7 speed cassette (if it is an 8 speed with a spacer, you can just remove the spacer and fit an 8,9 or 10 speed cassette on it), you can take a 9 speed cassette, disassemble it, taking the last cog off (the lowest speed cog), and putting it on the 7 speed cassette hub. You would need a 9 speed shifter, which you can still buy from Nashbar and other places, and you'd need a 9 speed cassette which you can disassemble, which means 105 or lower quality. But it works, and you get 8 speeds without having to change wheels. Further, it sets you up for 9 speed if and when you do finally change your hub.

I had this setup for several years on my commuting bike; it worked perfectly, and when I replaced the hub, all I had to do is adjust the limit screw on the derailleur to make it a 9 speed.

BikingGrad80

You can put 8 of 9 cogs of a 9 speed cassette on and get new shifters and a 9 speed chain. True 8/9/10 speeds require a new freehub and redishing the wheel. It also it requires widening the droupous for the wider freehub. 7 speed freehubs are spaced 126mm and 8/9/10 are spaced 130.

trustnoone

I measured my drops. 126mm. Bikinggrad80, would 8 of 9 cogs work for this?

Cheers,

M

the beef

Ah, yes - good call.

Brian Ratliff

It should. The spacing on the cogset is more related to the length of the carrier, not so much the dropout distance.

If you go the route of getting a new hub, it should be okay to just force open the dropouts to accommodate the 130mm modern spacing. When the standard was newly adopted back in the day, apparently the nuts on the ends of the hubs were rounded to assist in the spreading of the 126mm dropouts. Basically, if the frame is any sort of metal, it should be okay. One caveat: if the frame is really stiff in the rear triangle, trying to force open the dropouts might result in a bent axle on the hub. I don't know if this is a real problem, or just an old wives tale. On the bike that I was running the 8 of 9 on 7 hub, I was actually using a mountain bike hub on an aluminum, bonded lug Trek road bike, meaning I was spreading the 130mm dropouts to accommodate a 135mm hub spacing. When I finally upgraded to a true 9 speed road hub and I took the 135mm hub off, there was no sign of a bent axle.

trustnoone

Probably not a good idea with carbon fiber dropouts...

Doctor Who

No bike with carbon fiber dropouts will have 126mm spacing. The only carbon fiber bikes that were that size might have been the early TVT/Look CF frames, and since many of those frames have died from gallic corrosion, I doubt many people are going to run into any problems with trying to squeeze a 130mm hub into 'em.

trustnoone

I measured from the inside space between my drops and they were clearly 126mm. It is a 1992 carbon specialized frame. I may take it into the local shop and see if a new hub will fit without bursting.

Cheers,