Yesterday I had a XT shadow mech mangle itself into the spokes, so I'm in the market for another. I'm not about to ditch all the drivetrain in one go, but might be convinced to do it in bits if I can keep using some of the old gear or use 10 speed stuff as needed before the switch. Thinking back to the 8 to 9 switch you could do it with just shifters, cassette and chain. Is it the same this time? Specifically:
Will my 9 speed chainset work for 10?
If I bought a 10 speed chainset, would it work for 9?
Will a 9sp mech work for 10sp and vice versa?
Anybody know yet?
From what I understand the 10 speed rear MTB mechs have a different accuation ratio to the 9 speed ones. So in theory you won't be able to use a 10 speed mech with a 9 speed shifter or a 9 speed mech with a 10 speed shifter. I am sure some folk will get it to work but Shimano say it shouldn't be mixed.
Surely the indexing is controlled by the shifter not the mech, so the mech should work with either.
By that thinking you should be able to mix Shimano and SRAM shifters with rear mechs but you can't. It is not quite as simple as that I am afraid.
Shimano actuation does not match SRAM on the rear mech but because 10sp cassette occupies the same space as a 9sp thus the distance the mech moves is the same - its the spacing between the cogs thus its the shifters that would be the limiting factor.
So are we saying that one click of a 9sp shifter pulls a different length of cable to one click of a 10sp? And then presumably one mm of cable pulled would move the jockeys on a 9 and 10sp rear a different amount sideways? What about the front and chainset/mech/shifter compatability?
As I understand it, the total amount of cable pulled between top and bottom gear is the same. ie, if an 8 speed shifter pulls 4mm of cable a gear, a 9 speed shifter pulls 3.5mm or some such (numbers are hypothetical), resulting in the same total pull between all the gears.
All Shimano rear mechs use the same multiplier ratios (ie, movement of mech vs cable). So an 8 speed Alivio mech moves the same distance for the same amount of cable pull as a 10 speed XT or Dura-ace. The differences are in how well controlled the movement is - obviously more speeds needs closer tolerances on the mech.
As a result, you can run a 9 speed mech on an 8 speed drivetrain perfectly happily. The jockey wheels & cage are happy to work with the wider chain. I'd be surprised if you can't use a 10 speed mech with a 9 speed setup.
Have a look here:
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946#Shiftratio
Change the cassette and shifter and you'll be able to go to 10 speed. It wouldn't surprise me if a 9 speed mech worked reasonably well with a 10 speed cassette and shifter.
You can also do strange tricks with the cable routing to change the multiplier ratio:
http://www.sheldonbrown.com/dura-ace.html#alternate
With road kit it used to depend on the cassette spacing i.e old Campag and Shimano 7 speed had the same spacing as did Campag 8 speed, but not Shimano 8 speed. So 7 speed Campag and Shimano and 8 speed Campag all worked?
10 speed chainrings can be slightly narrower than 9 speed.
http://www.highpath.net/highpath/cycles/info/rear.html
Don't you mean this link?
http://www.highpath.net/highpath/cycles/info/cranks.html
Derailleur chains are the same internal width, they vary in terms of their external width. Chainsets tend to vary a little in how far apart they place the chainrings in order to optimise shifting - ie, 10 speed rings may be a smidge closer together than 9 speed ones. 9s are closer together than 8s.