10 speed cassette question
 

I need to replace my cassette and chain.

I am currently using a 9 speed front and rear D with a 53/39 front chainring. Can I upgrade to a 10 speed cassette and chain without having to upgrade the entire drive train?

If I understand correctly the 10 speed chain is narrower and should work on the rear d, but I am unsure of shifting on the front D.

BTW I am running downtube shifters.

I am sure this has come up, but a short search in the bar revealed nothing.

If your downtube shifters are indexed for 9 speed, then I don't think they will work with 10.
If you are using downtubes in friction mode, then you should be fine.

Yes and no mostly no. The derailleurs and crank are probably fine but the levers (at least the right) definitely would need replacing, or of Campagnolo, switching to 10s indexing cams, probably about a $75-90 job. The levers set the indexing which the right would have to be a part of any switch to 10s.

With Campagnolo the only other differences are front chainring separation, but it isn't critical, and FD cage width also non critical. With Shimano, I'm not sure that the 10s and 9s derailleurs share the same cable response ratios (someone please confirm either way), but otherwise it's the same story as Campy.

The levers aren't inexpensive so this can be a costly upgrade, and is something you'd need to think about.

If you continue to use downtube shifters all you need is the new cassette, chain and right side (rear) shifter. Your current crank, front derailleur, left side (front) shifter and rear derailleur will work as is.

10sp
 

Unless you are desperate to go to 10sp, then I would look for much better deals on new/lightly used 9 sp stuff.

as others have said, the indexing of 9 sp vs 10sp is off.
If you are friction shifting, then it would be OK.

I belive the spacing from 8sp to 9sp was the same, but that's a mute point as you would have only had 8 of your new 9 gears! :0

I've heard that 10-speed + friction shifting can work, but it's really touchy...

7-speed 4 lyfe! :p

They are friction. So then I would just need to "dial in" the shift? But, if the chain is narrower then wouldn't the front d shift funny. I assume the 10 speed chain is narrower and the 9 speed front d is wider to accommodate the wider 9 speed chain.

Not enough difference to matter.
My rain bike has 10 speed drivetrain, but I'm using a "6-speed" front derailleur AND crankset from 1985. Works perfectly.

Awesome thanks guys/gals.

I've seen instances where a 10sp chain is narrow enough to "skate" on the tips of the small chainring instead of dropping into the teeth, effectively putting the bike into neutral (cranks turn, chain remains stationary). That can be dangerous, so if you encounter that problem, you have a case where the chainring spacing needs addressed in one fashion or another.

In the bigger picture, if you want 10sp because it has a gearing option you really want and can't get on 9sp, then it's worth looking into. But if 9sp is getting the job done, you might want to stick with 9sp here.

I spend a fair amount of time worrying about how I'm going to keep 9 speed when my shifters wear out:) I have 2 sets of Ultegra 10 speed shifters in the garage but I don't want to go there!!

Campagnolo 8/9 speed derailleurs with a conventional B-tension screw (2000 and older) instead of the adjustment on the lower body have a different actuation ratio and won't work with 10 speed.

They do.

Thanks Drew, on both updates. I tend to discount 1st generation 9s because it's been a while and most are out of the pipeline. Anyway, we ended up replacing so many of those RDs because of upper body cracking. on the 2,000 production