Shimano 9-speed to 10-speed

I'm considering upgrading my road wheels to a set that requires a 10-speed Shimano cassette. Before I take this plunge, I'd like to know exactly all components I will need to replace on my 9-speed Shimano bike. My assumptions: Are all these required?

1.) 10sp cassette - REQUIRED for the new rear wheel/hub
2.) 10sp chain?
3.) 10sp rear derailler?
4.) 10sp STI shifters?

Also, I will want to use my existing rear wheel on my trainer. Must I change out the 9-speed cassette (to a 10sp) on that wheel to work properly with the new 10sp RD, chain, and shifers? Thanks.

 

Let me guess, you can get a deal on a Dura Ace (7800-SL or 7801-SL) wheelset? If that's the case, you may just want to wait until you can get the 2008 WH-7850-SL's. Unlike prior year's versions, the 7850's will be backwards compatible with 9-speed:

http://www.cyclingnews.com/tech.php?id=tech/2007/news/08-20

Even if you have to pay more for the 2008 model, you're still probably going come out ahead. Upgrading to 10-speed can be pricey.

But if you were just looking for an excuse to go 10-speed , then you'll absolutely need:
1) 10sp Cassette
2) 10sp Chain
3) 10sp Shifter/brake levers

Nice to have (not required):
1) 10sp crankset. Some people report 10sp chains working fine on 9sp cranks. Other's say the chain sometimes "rides" the inner ring on downshifts. Probably depends on the specific crank.

Not required:
1) Rear derailleur. Both 9sp and 10sp rear derailleurs have the same leverage or "pull", so it really doesn't matter. You can run a 10sp rear der. on a 9sp system, or vice versa. The main difference is the 10sp version is lighter and has larger diameter jockey pulleys which theoretically decreases friction.

 

Thanks for the advice Uhl. You're exactly right. I'm looking at a slightly used 7801-SL set for ~$400. If I were to convert to 10 sp, do you know if I would have to change out the 9sp cassette on my existing rear wheel to work with the 10-speed chain and shifter? Ideally, I'd like to keep my existing rear wheel mounted on my trainer and use the SLs for outdoors only.

 

Yes, you will need to switch out the cassette.

The difference between 10-speed and 9-speed isn't only that 10-speed has one more "click" but the distance between clicks is different. So the cassette needs to match the shifter. Now if you were running bar-end or down-tube shifters, you could get away with it by switching to "friction mode". But that's not possible with integrated brake/shifters.

But with practice, switching cassettes becomes a trivial task. I switch out mine all the time to change gearing depending on the course. I can perform the operation in less than a minute. It helps to squeeze the cogs together when removing and carefully placing it in an undisturbed location while it's off the bike so all the cogs stay lined up. Then when you put it back on you can do it in one fell swoop (as opposed to having to do each cog and spacer at a time).

 

Thanks again Uhl. One more quick question. If I need to buy two 10 speed cassettes, I may as well get two different configurations. I'll likely get a 12/27 and an 11/23. Do I need a seperate chain for each, or can I size the chain such that it will not be too tight or loose with either an 11 or 27 setting?

 

Getting two different combinations is a smart idea. You should just size the chain so it you're able to run the big-ring/big-cog combination (53x27). Not that you'll be riding in that gear for extended periods of time, but you wouldn't want an accidental shift into that gear to hork the derailleur.

If you follow Shimano's instructions for chain length, you should be fine (see attached).

The image is taken from the rear derailleur service instructions. You can find all Shimano's service instructions here:
http://techdocs.shimano.com/techdocs/blevel.jsp

 

One potential cost saver... but at the cost of a cassette, probably not a big enough deal to bother with it. And this is all hypothetical, as I haven't tried it.

When on the trainer, do you shift gears, or do you pretty much pedal along in a single gear? Or maybe a couple?

If you use a single gear, then I would say that you may not need a new cassette as long as your system works in the one gear you use... Even if it takes a click or two on the barrel adjuster, as long as you remember to adjust it back for your road wheels.

You may even be able to tune it so that a couple of gears line up acceptably... As long as you don't spend appreciable time in the gears that don't line up, it shouldn't wear anything excessively.

However, as stated, this only saves you the cost of a cassette. And it does have limitations.