9 &10 speed comparability help needed

[njec]

Hello. I am thinking of getting my old bike up and running and have a few questions. At present I have a early triple shimano 105 groupset 9 speed. My rear wheel is done for and I have a dura ace wheel to replace. Only trouble is the 9 speed cassette does not fit the hub.
1. Can I leave the 10 speed cassette on and just limit to 9 cogs
2. Will I now need a 10 speed chain
3. Would like to change chainset, at present square taper 68mm bb can I do straight swap over to different bb for modern chainset.
Thanks

 

[lpretro1]

1. Yes
2. Yes - thinner chain for 10spd
3. Yes - new ones use Hollowtech II type bottom bracket which just screws into where the existing bb goes. It is a good idea to have the bb part of the frame faced if it has not been done to ensure the bearing fits correctly - if not flat then you can get premature wear. LBS should be able to do that for you for a small number of pounds.

 

[accountantpete]

Hi

Have you got a 7800 hub (with deep splines) and is that why the cassettes won't fit?

The answers are:

1) No - the spacing is slightly different.

2) If you are still running 9 speed then you won't need a 10 speed chain.

3) Yes it's a straight swap (presumably English thread). You presumably want a Hollowtech chainset so just need that and the appropriate Hollowtech BB.

 

[njec]

Thanks for quick response.
I want to use the 7800 DA wheel which is 10 speed everything else is 9 speed.
As for me getting a new chainset can I get a 10 speed even though everything else (apart from wheel & cassette) is 9 speed?

 

[accountantpete]

Thanks for quick response.
I want to use the 7800 DA wheel which is 10 speed everything else is 9 speed.
As for me getting a new chainset can I get a 10 speed even though everything else (apart from wheel & cassette) is 9 speed?

9 and 10 speed chains are more or less the same except they made the outer plates a bit thinner on the 10 speed. So you can safely use a 10 speed chain on a 9 speed system.

As I said earlier - they reduced the spacing for 10 speed cassettes (but kept the overall width the same) so you will have problems using a 10 speed cassette with 9 speed shifters.