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PostPosted: Mon Apr 28, 2008 11:24 pm 
Old School Hero

Joined: Sat Jan 19, 2008 4:12 pm
Posts: 175
Hi there.
I've seen a lovely Cyclocross frameset for sale. The only problem is that it only accepts a 6 speed cassette due to a small rear spacing. Do you know of any 6-speed Sti levers and also what other options would be out there for me. Is the spacing between the sprockets the same as 8 speed, so could I use my sora shifters if I set the 6 speed rear mech up correctly?

Any advice would be gratefully recieved.
Thanks, Rob


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PostPosted: Tue Apr 29, 2008 12:57 am 
Devout Dirtbag

Joined: Mon Mar 03, 2008 11:02 pm
Posts: 117
Location: Manchester
Generally speaking, what takes 6 will take 7 so it shouldnt be a problem setting the bike up for 7 spd - 126mm to 130mm - as long as it's a steel frame.

Sora is around in 7 spd or you could use your 8 spd and have a redundant click. If you are patient then RSX/RX 100 come round on fleabay ocasionally.

luv'n'stuff

J


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PostPosted: Tue Apr 29, 2008 11:07 am 
Dirt Disciple
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Joined: Thu Dec 13, 2007 11:48 pm
Posts: 17
Location: in the shed
Another option, if its 126 OLN, is to use cassette compatible 7 speed hubs, fit eight of the nine sprockets and spacers from a 9 speed cassette and use 9 speed shifters. By using the stops on the rear mech this will use only 8 of the 9 clicks on the shifters.

Rich :wink:


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PostPosted: Tue Apr 29, 2008 11:58 am 
Old School Hero

Joined: Sat Jan 19, 2008 4:12 pm
Posts: 175
Thanks for the advice guys but this has 120mm rear spacing so a 7 speed hub won't fit. It's aluminium too so there's no way I'll be able to bend the frame?
Any other options?
:?
Thanks, Rob


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PostPosted: Tue Apr 29, 2008 4:46 pm 
Old School Grand Master
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Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5785
Location: Lost in Translation
6-speed road STI levers have never been made.

There were some 6-speed road freewheel hubs spaced narrower than the standard 126mm, but they also use narrower sprocket spacing than a standard six. The Suntour Ultra Six, for example, used 5mm (7-speed) spacing and fit a 120mm frame. They're rare these days, and if this is a bike you plan to use, it doesn't make a lot of sense to run it on rare consumables.

You do have a few options, depending how creative you want to be.

You can run friction bar-end shifters and a 5-speed block, as the bike would have been used originally. 5-speed freewheels are around, new, and probably will be for a while.

You could run a 'Shimpagnolo' combination. Older 9-speed Campag levers, a Shimano mech, and a 5-speed freewheel should work:

http://www.ctc.org.uk/Default.aspx?TabID=3946

Some 7-speed freewheels use a pair of threaded, overhanging sprockets in the 1 and 2 positions. Replace them with a single sprocket, and you have a narrow-spaced 6. This will take some homework to find out what will work and get a supply of parts, but you should be able to get it to fit your frame.

You could get creative with the hub. Hubs have been made with short cassette bodies - for trials use, for special applications like Moultons and the newish Shimano Capreo. Phil Wood made a series of hubs with special, short cassette bodies. You might be able to adapt something to fit into your dropouts. You can then use separate 9-speed cassette sprockets to build a narrow cassette to fit the hub, and use modern indexing parts to shift it. Again, this will take some research (and probably some time trawling eBay) to get a working system together.

You could fit a fixed hub, or a BMX freewheel or cassette hub, or a hub gear, as I suggested last time you were asking. That's probably the simplest solution, but means a single gear (or a reduced range of gears). You can actually cram three sprockets on a Shimano DX BMX freehub...


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PostPosted: Tue Apr 29, 2008 7:46 pm 
Old School Hero

Joined: Sat Jan 19, 2008 4:12 pm
Posts: 175
Thanks Jim. That information is very useful. :D
The Capreo hubs look good but are still 130mm or 135mm wide despite the short freehub body. Any ideas on how this would be shortened?

Also any ebay search tips for these 5 speed freewheel hubs. No luck so far.

Thanks again, Rob


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PostPosted: Tue Apr 29, 2008 8:23 pm 
Old School Grand Master
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Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5785
Location: Lost in Translation
Rsmith wrote:
The Capreo hubs look good but are still 130mm or 135mm wide despite the short freehub body. Any ideas on how this would be shortened?

This is a little technical, and I have to stress also *theoretical*. I was planning something along these lines for an old Moulton, but my plans went in another direction. Capreo hubs are also expensive new, and scarce on the used market.

Here's a pdf of a Capreo hub, exploded:

http://techdocs.shimano.com/media/techd ... 608921.pdf

You can see that the freehub body is unusual in that it mounts deeper in the hub shell than a normal freehub, and has a narrow extension on the right hand end. This extension can be removed, and the thread underneath is the same as for a normal Hyperglide lockring. You can fit six or seven nine-speed spaced sprockets to the remaining short freehub body. That removes quite a lot of width from the hub already. If you need to get rid of more, there are two spacers on the left hand side that are now redundant.

You'll need to replace the axle with a shorter one, and you'll need to do something about sealing the right hand bearing. A normal press-in Shimano dust shield will probably work, but I can't guarantee it.

Quote:
Also any ebay search tips for these 5 speed freewheel hubs. No luck so far.

You can re-space just about any threaded hub to suit 5-speed, but a search for 120mm hub* in Cycling - title and description worked for me:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0220035856
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0254064255
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0217505784
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0249760114
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0229599676
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0213441288

The thing is that this stuff is either collectable (and expensive) or worthless (and not worth the hassle of eBaying). You'd have more luck at a cycle jumble.

To be honest, I really think the only practical route is to go singlespeed, but there's no harm in looking into the other possibilities.


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PostPosted: Tue Apr 29, 2008 9:07 pm 
Old School Hero

Joined: Sat Jan 19, 2008 4:12 pm
Posts: 175
Thanks again for the detailed reply. The new Shimano hubs probably are out of the question. I am mechanically minded so would give it a go, but I think I would have to look 2nd hand as they are a little pricey.
Thanks also for the ebay links, I'll have a look over those now.

You are right though, singlespeed does seem the best (and least hassle) option. I already have a geared CX bike and this retrobike would be used only for recreational use. Definately something to consider.
I suppose if singlespeeding wasn't for me I could, as you said, fit a geared hub.

Thanks again (again), Rob


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PostPosted: Tue May 27, 2008 2:26 pm 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8661
Alternative number 1, use front 3 chainrings only with a 3 spd sti shifter and a single 3/32nd type BMX freewheel on the rear with a tensioner such as a short cage rear deralier.

Alternative number 2, if your feeling flush how about a schlumpf drive ie a 2 speed bottom bracket mounted gear system that you change gear by hitting a button in the centre of the cranks with your heels.

Alternative number 3, a hub gear with automatic gear change as I believe exists in a 4 speed format from either Shimano or SRAM.

Where there's a will there's a way.

Cheers


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