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I’ve been playing with the idea of converting my 9 speed XT drivetrain to 10-speed (I’m convinced that in a couple of years, 9 speeds will be gone).
Its a confusing mess. The cassette is the easy part, it just falls in place, and the 10 speed shifter trigger also is easy.
But I’m really confused with the derailleur, chain, and chainrings.
It seems to me that the 9 speed derailleur should be able to handle the new cassette. The Large gear is still a 34 tooth unit so it isn;t being asked to stretch any further than it used to, and the limit screws can be opened up enough to let it move over the gears effectively. The movement is largely controlled by the trigger, not the derailleur itself.
The chainrings also seem like there should be no difference. But Shimano clearly lists a 10 speed "dyna-sys" chainring for the XT770 crank as well as a 9 speed unit. I don’t have one of each in front of me, but it seems unlikley that there is really much difference. If both bolt to the 770 crank arms, the lateral spacing would be very similar it would seem to me. Perhaps the outer rings might be machined asymetrically to narrow the gap, but the center ring still needs to be in the center — right? What would eb the actual difference?
Similarly, the 10-speed chain should be a no-brainer — 10 speed chains are narrower, that’s a given.
But Shimano says that the only chain that will work with the 10- speed dyna-sys stuff is a dyna-sys chain. I’m told that it is unlikely that I will find satisfactory result with a standard 10-speed chain. Why?
Has anyone done this conversion? I’m just wondering what I’ll run into.
I have a new 10 speed XT cassette on the workbench, along with the 10-speed XT trigger, and a new XT 773 (10-speed specific) rear derailleur (which doesn’t really look too different from the 9-speed version). I have a couple of new Dura-Ace 10 speed road chains. I do not have 10-speed specific chainrings, and I’m beginning to doubt the need for the whole conversion process.
Any thoughts before I unbox everything and dive in??
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Hmmmmm.
Well, here’s what I’ve done so far.
I replaced the 9 spd shifter with a 10 spd varient. That was easy. There are two little screws that hold it to the bar clamp, and I unbolted and rebolted. Externally the 9 speed and 10-speed XT shifters are identical.
I pulled the old cassette and replaced it with the new 10 speed one.
I pulled the 9 speed derailleur and replaced it with the dyna-sys 10 speed type. The mounting point for the shift cable is quite different on the 10-speed variety and it appears to alter the geometry a bit. The cage and parallelogram on the two derailleurs is otherwise identical, but the 9 -speed doesn’t move quite as far from low to high as the 10 speed one does.
I attached a new Dura-Ace 10 speed chain that I had on the bench since the tech spec for the shifter said only that it needed a 10-speed chain.
No good — the road chain doesn’t work properly. I don’t know if it is the chain’s fault, or if the "dyna-sys" thing requires something special. I also don’t know if the chain-rings — regular old "Mega-Sys" types from a Shimano 770 crank might be to blame. The 10-speed rings are a bit narrower at the gear teeth it appears.
The problem right now seems to be that the chain is not be moving properly over the lower guide pulley and it makes the chain jump a bit as the chain passes over it on the way through the pulley cage — and yes, everything is properly adjusted and the Park Tools derailleur hanger "checker" says the hanger is on properly — keep in mind that everything in the 9 speed setup worked perfectly.
I have a Dyna-Sys chain and replacement 10-speed chain rings on the way. The Shimano guy I talked with said there was no difference in the 770 and 770-10 crank arms or bottom bracket.
I’ve looked carefully at the 10-speed specific front derailleur and I really don’t see a functional difference in the two. I’m opting to retain the current front derailleur.
Right now, I’ve spent about $475 on this changeover. I have the 9 s-peed rings, chain, rear derailleur, and shifter which I can probebly get a hundred bucks or so for so my total cost for this project is gong to be around $400.
It remains to be seen if it is worth it. Right now, I’m guessing that it probably is not. But its been a fun project, and I’ve learned a bunch of stuff, so there has been some return on my investment already.
Plus — I have a kinda unique bike that I feel good about.
Stay tuned — I’ll let you know how it turns out.
(by the way — for those of you who have ever wondered — I put the old 9 speed derailleur on my 10 Speed road bike along with a 11-34 casette just to see if I could do it. The local mechanic said no, but I find that it works perfectly aslong as it is the 9 speed derailleur and not the new dyna-sys 10 speed. It didn’t work with the road bike’s shifter. So for those of you who might have wanted "mountain" gears on your road bike — here’s an option)
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