Update old bike - potential issues

[RuralSpaceman]

I have an old Specialised Cirrus which has a stupidly low brake hanger between the seat stays, preventing the use of tyres of section bigger than 25. I would like to transfer the components - mixed bag but triple chainset / 8 speed, 105 brakes and good wheels - to an old Raleigh frame which has better clearance but unfortunately also has bolt-on wheels. The Raleigh has some Shimano kit on it so at least it's metric.

I haven't measured the seat tube diameter nor the BB spindle lengths or distance between rear drop-outs yet so I don't know how similar the geometries are but I do anticipate a few problems.

1) I know that the Raleigh will need a new hanger to accommodate the derailleur from the Cirrus but what happens at the non-drive side? I imagine that there is a lot of scope for the q/r wheel to be installed squint unless there is a clear place for it to anchor in the long horizontal drop-out.

2) How do I know what length of BB spindle I need. No doubt they won't be the same length on both bikes so how do I work out how to accommodate the triple in place of the current double as well as preserving the chain-line?

3) How do I work out how long the chain should be?

If there are any other issues that I should have anticipated or questions that I should have asked (apart from "is it worth it?") , please let me know - ideally with bright ideas about how to get round them, thanks! Otherwise, I'm sure that I'll find plenty along the way to keep me going.

Thanks,
Stuart

[mattsccm]

i wouldn't worry about the drop outs. Either just ensure that the wheel is straight before you swing on the Qr or pull it right back. Many bikes with that sort of drop out had a small adjuster screw but many (more ?)don't.
Poke around the junk bin of bike shops and you will find the hanger you need. Its like the one fixed to the mech in your pic but that one is permenantly fixed on. You use the normal mech bolt to screw the mech to the hanger. The hanger than is held in place by the axle and QR. Some hangers have a small bolt that guides it in place. You may have a need to fiddle with the axle length but I would cross that bridge later if needed.
Before you spend too much time on it just look for that hanger.

[531colin]

Will your existing brakes reach the rims in the other frame?
Swap over the chainset and BB as a unit.....its the chaunset that governs the BB length, not the frame.

edit...gear hanger will dictate position of wheel in slot......just line it up centrally.

[RuralSpaceman]

Thanks - good info to get me started. Might take a few days to get into gear on this and the "will the brakes reach the rims ?" question did cross my mind this evening - there's a difference of about 1 cm between the distance from the seat stay brace to the drop-outs from one bike to the other. If they work okay and I can get a hanger - sjs sell something that looks like it might do the job - then I'll get the Raleigh BB out and measure up the Cirrus spindle length (old cup and cone BB so not for re-use) so I can get the right sized cartridge BB.

We'll see. I'm sure I'll be back to this thread or a close relative. Thanks again.

[PBA]

When I swapped to a different mech hanger, I bought two and put the other on the non-drive side. It does nothing more than locates the QR... If the new mech hanger is the same as the existing mech fixing you could just saw off the bit you need from the existing mech. In theory you shouldn't need to do it as the QR should be tight enough to hold the wheel where you clamp it. My problem was that it used to move when I pushed on the clamping lever!