7 speed gearing on a 126mm OLN bike

[NorthernMtbr]

I have a 1990 dyantech racing bike that is 126 OLN at the rear. My bike was bought as a frame and built up with a chorus groupset so it doesn't have a 7 speed indexed shimano set up as per the following catalogue.

http://www.retrobike.co.uk/gallery2/v/M ... 0.pdf.html

I currently have a 13-28 freewheel on a campag chorus hub. The catalogue for this campag hub says the max width of the 6 or 7 speed freewheel is 32mm. So if I wanted to go to seven speed freewheel I think I would need a different wheel as the 7 speed IRA freewheel on spa cycles is 34.1mm wide. So another option would be to get a 7 speed cassette hub wheel.


My question is with the bike that I have can I get a 7 speed cassette wheel that will fit and what would be the cassette width and would an old hub like this be compatible with the spline on a new 7 speed cassette? I know I may have to stick with what I have got but If I can get an old 7 sped wheel I may be able to get a better range of gears on a cassette compared to my current freewheel.



Thanks

 

[one-eyed_jim]

There are 126mm 7-speed road cassette hubs around. Shimano made them for the 105 (FH-1055) and Ultegra/600 (FH-6401 HG) ranges. The Ultegra/600 model's nicer, but they're not easy to find: they were only produced for a couple of years before 8-speed became the norm. Either hub will take a standard 7-speed Shimano Hyperglide cassette, or (if you're feeling adventurous) eight ninths of a nine-speed cassette.

You may be able to respace your current hub though to accommodate a slightly broader freewheel. The downside is a little more dish to the wheel, and a little more axle overhang.

 

[beenbrun]

126mm OLN bike

I bought a roberts bike with a rear 7 speed campagnolo hub and it is 126mm. I've measured it with a digital measurer. I'm going to push it out to 130mm OLN so I can sell you the wheelset if you like the look of it? Would you be interested?

 

[NorthernMtbr]

I did wonder about re spacing the hub as there is a spacer between the two lock nuts on the non drive side. This spacer is about 1.2mm thick. To get up to the 34.1mm width of the IRD 7 speed freewheel on Spa cycles I think I need an extra 2.1 mm as my campag hub is limited to a 32mm width freewheel. I would have to remove the spacer from the non drive side and machine about 1mm off the outer lock nut on the non drive side. Then I would add 2.1mm of spacer(s) to the drive side and finally dish the wheel.

Would re-dishing the wheel an extra 2.1mm be okay as I don't know if I could really do this without damaging anything?

It would be easier though to leave it as it is or just get a cassette wheel.
What effect will the extra axle overhang have can it break or is that unlikely?

Beenbrun: What type of hub and wheelset is it?

 

[beenbrun]

It's actually a sachs 6 speed (13-2 but I've re-measured and it's definitely 126mm. It's an old campagnolo hub on a mavic rim.

 

[NorthernMtbr]

Hi Beenrbun, that wheel won't be an upgrade for me so it would be no use as I already have a 6speed chrous freewheel hub. Ideally I would need a hub that would take a cassette.

I now know that my rear derailleur can only go to 28 teeth so I will have to change that as well if I want a lower gear that 28t at the back.

 

[Pionir]

Re:

You can definitely run a 7speed freewheel on Campagnolo Chorus hubs in 126 OLN spacing as that's what I've got at the moment. Getting hold of a 7sp freewheel and getting the old one off might be a bit of a challenge though!

It might be your hub is 6sp only though, in which case a new cassette hub would make more sense. As has already been mentioned the 1055 is 7sp hyperglide. The 6400 hub is 7sp uniglide, 6401 7sp hyperglide.

I actually have a spare 6400 7sp uniglide wheel (13-21) on a mavic module 3 silver rim, into which I've put new bearings and cones/axle this winter which I'm going to be selling shortly. Pm if you're interested

David

 

[NorthernMtbr]

Hi

Thanks for the help.

My chorus group set was bought in 1990 so I think the 1988 manual must be the right one for my parts.

If you go here http://velobase.com/Resource_Tools/CatalogScans.aspx

to the campag 1988 dealer parts catalogue and look on page 35 it says max freewheel width is 32mm and here http://www.spacycles.co.uk/products.php ... 0s112p3087

for the 7 speed freewheel I was thinking of getting the width is 34.1mm. I did see some ultra 7 speed freewheels on e bay but they were NOS in the US and were too expensive. So my assumption was that I can't get a new 7 speed freewheel that is 32mm wide. If this is wrong please show me where I can get one?

I should be able to get the freewheel off as I upgraded from 5 speed to 6 speed last year.

The advantage of a cassette wheel is that I can get a 12 tooth sprocket which I can't as far as I know on a freehweel, plus my lowest gear could be lower than 28.

Regarding your wheel, the rim may be the wrong size and a bit old but I might be interested in the hub.