Very confused re Wheel/hub/freewheel/cassette....

jimmyhorns

To cut a long story short, I am trying to make one good bike from two 'bad' bikes.

I want to take the shimano rsx gearset from a GT ZR4000 and put it on a British Eagle tourer from the 80's as a commuting bike.

The main reason for wanting to do this is that I dont like taking my hand off the handlebar to change gear, and I like to be able to change gear and brake at the same time. There is a side issue of the brake hoods having perished on the british eagle.

The british eagle is a 126mm dropout at the back, and the GT a 130mm - I plan to cold set the frame, and am not too worried about this.

I 'think' everything else will swap over easily in terms of fitting and that the travel on the brake levers will be acceptable.

The thing that I really dont get, and now need to know about is the rear 'gears'. I say 'gears' as I really dont understand the correct terminology, with things sometimes being interchangable either the words or the items in use!

Originally I had hoped that I would simply be able to swap the tyres over on the rear wheel, and use the rear wheel from the ZR4000, however the rim is too narrow to take the 700C 32 tyres that I want to fit.

So I am now in the position of either needing to build a new rear wheel which will work with the rear rsx derailleur, or modifying the existing rear wheel to take the wider tyre. I had thought about just swapping the 700 rim over from one bike to the other but unfortunately the spoke count is different 32 vs 36 so I cant do that. The shifter is a 8 speed version.

Please can someone help explain what I need in terms of the parts and their names.

Thanks

James

James

ugo.santalucia

Are you sure the rim is too narrow?

Best way to try is to put the tyre on and inflate it 30 PSI over where you would be happy to use it... so if you plan to use it at 60 PSI, pump it up at 90... if it stays on the rim then it's going to be fine, if it pops off the rim, then it's not fine.

If the rim is not fine, you could re-rim the rear wheel. so find a rim with similar internal diameter (ERD) and swap it over. Mavic make some reasonably priced touring rims... the A series A119, A319 etc

cougie

Are you trying to put 700c onto a 27 1/4 wheel ?

jimmyhorns

ugo.santalucia wrote:

Are you sure the rim is too narrow?

Best way to try is to put the tyre on and inflate it 30 PSI over where you would be happy to use it... so if you plan to use it at 60 PSI, pump it up at 90... if it stays on the rim then it's going to be fine, if it pops off the rim, then it's not fine.

If the rim is not fine, you could re-rim the rear wheel. so find a rim with similar internal diameter (ERD) and swap it over. Mavic make some reasonably priced touring rims... the A series A119, A319 etc

I did a bit of research and I didnt think that you could get a 700 32 onto the same rim as a 700 23 - its a mavic wheel which came stock on the GT ZR4000 and looks very slim indeed. Is it worth getting the tyre off and measuring the internal rim measurement?... I guess it might be

Thats a nice tip for checking whether it will work on those rims, so will give that a go too - just seems like a lot of tyre to be supporting over a thin rim....


If it does work I am still going to 'need' to change the cassette / freewheel (I dont know which it is or what the difference is if I am honest). The granny gear is way to small for the steepest incline on the commute

jimmyhorns

cougie wrote:

Are you trying to put 700c onto a 27 1/4 wheel ?

Both wheels are 700C one is a 23, the other a 32 in terms of tyres.