Changing from 7-speed to 10-speed cassette?

What do I need to change?

I'm currently running a 7-speed Shimano cassette with down-tube friction shifters. My newer wheels though are to be equipped with a 10-speed Campag cassette.
I got the bigger cassette to help with the hill climbing, but am worried now that I might have to change too much other stuff...

I'm looking around for a new rear dérailleur to match, but want to change as little as possible in other respects:
The front half is currently fitted with Veloce mech & Veloce double chainset/cranks.
I'd prefer to stick to down-tube friction shifters - only partly for the retro value - but mainly because it's the only way I've ever known.

Questions:
1) Is there any reason why my existing shifters won't work with 10-speed cassette & a new derailleur?
2) Does a new rear mech have to be quite a specific kind: ie. 10-speed or a certain cage length? How different are 9-speeds, long cages, etc.?
3) Is 10 on the back ok to run with a double on the front or is it better to go triple on the front (which I guess would also mean a different bottom bracket)?

Is it just me or were old parts not quite so confusing?
Thanks for any info

Old parts are great, that's why we're here

What rear mech are you running now?

What I would do personally is wait for your new wheels to arrive and try all of your existing parts prior to investing in anything new. To attempt to answer your questions:

1. No reason why not. I'm guessing that in maybe a little harder to fine tune into the right gear as they are closer together but again no reason why that cannot be done.

2. Yes and no. Cage length will depend upon your largest sprocket size, if it is below 26t then a short cage mech should be fine. You may get away with the travel of you rold mech across all ten sprockets, you may not. A 10 speed specific rear mech will ensure optimum compatibility but where's the fun in that!?

3. Double is fine.

You will need a 10 speed chain.

Hope that helps.

Ok - that mostly makes sense - thank you.

I currently have a Shimano 105 on the back. The cogs on cassette will be 12 through to 25.

No reason why I can't give them a spin pretty soon...

I didn't realise there was such a thing as a 10-speed chain though!
How does that differ?

It's narrower you certainly won't get away with a 7 speed chain...

105 might do it, give it a whirl and see.

Excellent - that does make sense about the chain.
I changed the chain a little while ago for a NOS i'd had sat in a drawer - i seem to think it was bought for a tourer or maybe a mountain bike which had big cassette.
Can try that this week...
Thanks.

Hi, you might find the spacing on the back too narrow for your new wheel.
130 or 135 instead of 126mm. If this is the case and you have a steel frame, it can be "cold set" to fit your new rear wheel, or "spring" the rear apart everytime you change the wheel. This can damage the bearings if they're sealed.
If you are happy that you will be sticking to a 10 speed, it may be better to cold set. Check out Sheldon Browns website for instructions,

Stu

Ten speed mechs are narrower between the jockey cage plates: although your current mech will travel far enough, the jockey wheels won't be directly under the first and tenth sprocket. Also, the jockey wheels will be too wide for the ten speed chain to sit properly.

135mm is MTB standard, the new wheels will be 130mm, which can happily be accommodated between 126mm dropouts and I've never heard of any damage to bearings: the threaded nuts on the axle will prevent any excessive force being applied to the bearings.

Double or triple, the choice is yours: the number of sprockets isn't relevant, but you will need ten speed chainrings.

If you run anything other than a ten speed chain, you will damage the drivetrain (if it even works): ten speed chains are narrower between the plates and the rivets are flush; sprockets and rings are thinner to suit.

Thanks v much for all the info:
Firstly, the wheels seem fine with the spacing - a little tighter than the old ones, but not so that it feels you're forcing the stays apart.
Second, the chain I have doesn't work, so I'll have to wait until I buy a new chain before I can test my existing mech... They're not cheap are they?! Will let you know how it works & will keep my eyes open fora good deal on a 2nd-hand mech in meantime...

To back up what others have said the very minimum you will have to buy is a 10 speed chain and you will also need to re-space the rear drops to 130. As long as that set up seemed to work I would upgrade to 10 speed brake shifters next just because the shifting will be much smoother and it generally is best to have the cassette and the shifters in the same generation.

The inside of the chain is the same thickness across 7 speed and higher. You might get away with the existing rear mech and 10 speed cassette with enough throw. The only way to know is to try...