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Derailleur Choice
Shimano XT M786 Shadow+ 10 Speed Rear Mech
or
Shimano XT M781 Shadow 10 Speed Rear Mech
Anyone got the new Shadow+?
If you do, what's your experience with it? Is it worth the extra $20.00?
And while we are at it, can anyone explain what's the difference [performance wise] between a medium and long cage?
Thanks,
Alberto
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Thanks,
I also saw the previous post [a week or two ago] about shadow +
So I think I will try the +
Ta
Shadow Plus is definitely worth the extra $20. The clutch mechanism really helps with chain retention and chainslap noise! (That said, I've actually got the SRAM Type 2, same idea).
Cage length, see above post
No idea on the shadows but my understanding on the difference of cage sizes is to suit either a compact cassette or a large cassette. Ie 12-28tooth vs 11-32tooth
Then again I could be completely wrong
Derailleur length relates to the tooth capacity of it to deal with the variation in gearing you can have.
Say you are running 2*10 38/24 front rings with an 11/36 cassette. You would need a Der to deal with a 39 tooth capacity ((38-24=14)+(36-11=25)=39T
If Running 2*10 with 36/24 and 11/34 Der - then 12+23=35T.
If Running 3*10 44/33/22 with 11/36 then 47T capacity (44-22=22)+(36-11=25)=47T. Note 3*10 systems don't need the full range as you don't/shouldn't use large/large or small/small rings/sprocket combinations - so change the numbers to suit.
Typically long cages run up to 45T, medium 37T though there are differences between SRAM and Shimano. Can't guarantee the following is correct but I believe the capacity of Shimano are long=45T; Medium 33T, SRAM long=43T; medium=37T. However they typically can go one or two teeth higher than rated capacity BUT suspension design and travel can have an effect.
Choose the shortest one that meets your systems capacity.
Can't help with Shadow nor do I know their capacity.
The + is worth the extra $20 and 30grams
If you're running triple chainring you'd probably need the long cage, double or single chainring might get away with the medium cage
Thanks for this.
I'll just have to go do some maths and figure it out!
Much appreciated.
Im running 2*10 26/38 with a 11/36 cassette. 12+25=37T.
So Shimano means long? I'll check what they are rated to!
Thanks again,
A
I've just insatalled a Sram type 2 medium cage with a 40/28 up front with a 11-36 casette. This is slightly outside the reccomended 37T capacity but so far it seems to work fine. Definatley reccomend a clutch type RD, wether it be Sram or Shimano for less chain slap and better retention especially on a hardtail bouncing around on bumpy down hill sections. Just remember that Sram shifters and Shimano derailleurs are not compatible and vise versa.
Quote, "Im running 2*10 26/38 with a 11/36 cassette. 12+25=37T. So Shimano means long?"
In my experience Shimano have a bit of leeway in their cage capacities.
I recently installed a 24/38 - 11/36 XT drivetrain, so my capacity is 39T, slightly more than yours. Shimano rate the meduim cage (GS) M786 at 35T, but I used it and it was fine, and I do use all my gears!
That was on a short travel bike (100mm) so you'd have to be more careful if your bike has significant chain growth due to longer suspension travel. But even then, you can always just add an extra link, and avoid the small/small combo.
By the way, agree with those above that the shadow+ is worth the extra twenty bucks - you'll save that much anyway by not having to buy a chainstay protector...
Worth noting that although chain length is set when in big ring to big ring, you should never be riding like this.
This is Known as cross chaining where you are using Big ring at the Crank and big ring at the cassette. Same goes for small ring to small ring. This can lead to higher chance of chain and/or sprocket failure.
A lot of people do it and many don't realise they are doing it.
When riding in big ring/big ring the derailleur is near/on maximum reach. Not a good thing for the derailleur.
What you say is a reasonable rule of thumb for triples, but remember the OP is running a 2x10, and most mountain doubles have their 'big' ring where the middle ring is on a triple. So, its not such a no-no to use big/big on a double because the cross-chaining is no worse than using the whole of the cassette with the middle ring on a triple. However, it is worth adding an extra link in addition to the big/big +2 rule so the cage isn't under too much strain.
Afterall, I find there's times (races usually) when I just want to stay in the big ring on my double and use all ten sprockets rather than mess about with front shifts. Will my drive train wear faster because I cross chain - yes probably. Will it explode into a thousand pieces because I use big/big - thankfully not!