Bicycle Mechanics - old 7 speed freehub
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I have an old steel Somec - 20, 30 years old with Shimano 600 groupset. It has a 7 speed freehub, which my LBS says is obsolete (really?). Is there still a source for these or only Ebay? Basically, it has 53/39 rings and 12/24 t sprockets, d/t shifters,brazed on hanger for the front mech. and is on sprints and tubs. A couple of sprockets are worn and slip at times so at the least I need to swap them. However, bottom gear is er, too high (44") - bike is in Denia, Spain where the hills are really hard work... So another freehub with a 30t sprocket would be welcome. But I'm fed up with carting 2 spare tubs around instead of a small puncture outfit. Consequently I'm considering swapping the wheels for modern ones with clinchers and fitting a compact chainset 50/34. The front mech can be lowered 1/4", or more with use of a file. Rear drop outs are 126mm but I'm sure 130mm will fit easily. Obviously I'll need to change the front and rear mechs.
So, I have 2 choices, keep bike as it is if I can source a freehub, or go the whole hog and fit modern parts to it ( this appeals most if finance runs to it...) I want to sort out the viability of my options and then obtain the parts here in the UK before bringing the bike home from Denia, possibly September.
Thanks for reading this far, all comments, suggestions welcome.
Lots of versions of the 600 freehub, some were Uniglide, and Hyperglide. I replaced the 600 Uniglide on a wheel I had, with a donor hyperglide freehub. That can sometimes work (they also had a variety of mounting designs).
Short answer, without pulling the freehub, no idea. 7 speed cassettes are readily available, at low cost.
A lot of shops around here have no understanding of older bikes, and have told me everything I have is obsolete. Kind of a standard answer really, if they don't know, "its obsolete, you can't get them anymore".
Spend some time on the Sheldon Brown site, it goes through it thoroughly. In addition, there was a post on here a couple of weeks ago with the oddball freehub attachment.
Here's the recent thread, with the oddball freehub attachment.
07-12-12, 04:47 PM
I'm a big fan of 7-speed -- get a 12-28 cassette and switch to a compact crank and you'll be in business.
Are you sure it's a freehub with cassette and not a freewheel?
07-12-12, 08:28 PM
If your rear hub is 7-speed Uniglide freehub, it most likely uses the 10mm allen fixing bolt and you can swap in a HyperGlide freehub (I did this on a 105 7-speed Uniglide hub). But there's really no need to do that. You can get a 7-speed HyperGlide cassette and grind down the fat tab on the 6 biggest cogs and they will then slide onto the Uniglide freehub. Then use your 12T threaded Uniglide cog to lock them all down.
If your 12T cog is too worn, you can get a replacement here ... http://www.loosescrews.com/index.cgi?d=single&c=Cassette&sc=Loose%20Cogs&tc=Shimano%20Uniglide&item_id=SH%203571210&id=4665176006 . It's a 6-speed cog but the smallest cog is not an index stop and is instead controlled by the derailer limit so it will work as long as the cog does not hit the frame. And you could always grind the built-in spacer down a little to be 7-speed spacing.
Thanks for the replies, I didn't realise there were several different freehubs. I wasn't able to bring the bike home unfortunately, so I don't know which type is fitted. My LBS said it was not a freewheel but a freehub,and not a modern cassette. I never even thought of taking a photo, doh!
Ah well, food for thought and I've a few months to check prices and sources. I'll post again when I've sorted everything out.
07-14-12, 06:54 AM
You have quite a few options: new cassette, partial conversion, full conversion. Full conversion is nice if the frame and rest of the bike justify the expense. I did a budget version for about $350 with mix of new & used. You can keep the crankset and front derailleur. You could do partial, with a newish rear wheel, cassette, chain but keep the old shifters and run "friction" mode, or use 10 speed indexed downtube shifters. Used, NOS, and/or brand new will determine total cost.
07-14-12, 11:52 AM
Also try flipping the worn UG cogs over -- if you always mounted them the same way, then only one side of the teeth is worn. It's not a long-term fix since good UG cogs are hard to find, but it is a cheap and easy fix that works well.
The UG cassette cogs are among the very few that can be reversed without shifting problems.
Alternately, 13-30t and 13-34t, 7-speed HG cassettes are still available. You'd only need a new derailer and longer chain, and your crankset would likely be fine as-is. A 13t threaded cog would replace the splined cog of the new cassette, with almost no chance of chain contacting frame even using the 6sp-spaced version.
GonzoBob is right, the biggest tab on each cog needs to be filed a little after the cogs are separated, but I've also seen the whole cassette filed out at once (held in a vise, using a bigger file).
08-06-12, 10:58 PM
I just went through a very similar situation. I actually ended up with two 7-speed cassettes from members here. One, a NIB 13-23 (the gearing I already had) and a lightly used 13-26 (the gearing I was hoping for). I wanted the bigger sprocket for hills so put on the 13-26, bought a new chain and am as happy as a clam. I seriously considered the readily available HG 13-30 or 13-34 cassettes, but went with vintage UG for the sake of vintage. :D
The absolute cheapest for you would be to simply clean it up, get an HG cassette, file it down, get a new chain and go with it. I think you could possibly play with the derailleur angle adjustment to get it to work with a larger sprocket and cut the cost of a replacement. Sheldon also explains how to do this (http://sheldonbrown.com/derailer-adjustment.html). Park also has a decent rundown with pictures and diagrams (http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur).
Thanks again for the replies. I can't wait to get the bike home and sort out the gears and one or two other little jobs! I will use it then until winter - then decide whether to keep the bike as is or go for clincher wheels and compact chainset...
Dunno if asking Father Christmas will bed of any help...................!!!
A few points to consider:
* HG craps on IG. Definitely a worthwhile upgrade, even if you're friction shifting.
* Pff, your old 600 hub is 'obsolete'. It's a lovely bit of work, and easily upgradeable with a second-hand part you can find for nothing.
* Whether you should upgrade to an 8/9/10spd cassette body or a 7spd HG one depends on whether you really, really want another gear or not; 8spd doesn't wear significantly faster than 7spd (although 9 & 10spd do), but the longer cassette body makes for a weaker wheel for a given OLD, and the shorter cable pull per shift is less reliable and more finnicky.
* If you had a 126mm OLD aluminium frame you couldn't spread and wanted a wider cassette body, this isn't recommended, particularly if you're heavy - but it's perfectly fine if you use an off-centre rim.
* The 5mm spacing of Shimano 7spd is identical to Campy's 8spd spacing, so old 8spd Ergos and RD will work. These are generally more reliable than STIs; easily rebuildable and all that usually happens with them is you need to tweak a bit of tension back into the indexing springs. The best front shifting of any brifter, and it'll work a triple. Remaining with 7spd will avoid the need for a re-dish and maybe a new axle, not that that's a big deal.
* Jtek's various models of Shiftmate allow you to mix and match shifter/derailleur/cassette brands and speeds to a large extent.
go for clincher wheels
Hey, you have tubulars on that baby? Cool!
I heard the go is to throw a little Stan's sealant (for tubeless tyres) in there; I've been thinking about building up myself another set of singles ever since...
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