Rear Mech Problem

spennie

Über Member
I'm having problems with my rear mech, i've just put on a shimano deore lx 10 spd rear mech with a new set of shimano dura ace 10 spd bar end shifters. The problem I'm having is, i cant get the highest cog on the cassette or when i can get the largest cog, by adjusting cable tension( cable and barrel adjusters) or the adjusting screws, i can't get the lowest cog. So please can someone give me some advice, on how to cure this problem. ( i use a sram 10spd cassette, which to my knowledge has always been compatible with shimano ).
 

screenman

Legendary Member
I may be wrong but I do not think they are compatible.
 

raleighnut

Legendary Member
Location
On 3 Wheels
^^^^ +1 Dura-ace tends to only like other Dura-ace bits, mind you it is possible to turn the indexing off on the bar ends.
You may need to get a Dura-ace long cage rear mech to match the shifters, or you may get away with a 105 ten speed rear mech (long cage)
 
Location
Loch side.
It is not a Dura Ace issue but Shimano MTB derailers are not compatible with Shimano road shifters. The pull ratios are difference every since 10s-speed. You'll see the words Dynasys somewhere on the derailer. That's French for incompatible.
 

starhawk

Senior Member
Location
Bandhagen Sweden
The Shimano and SRAM derallieur have differnt pull but as I understand it the cassette have the same spacing so if the derallieur and the shifters are the same brand it should work but some derallieurs are not compatible with 3 wheels up front so that may be your problem
 

mcshroom

Bionic Subsonic
It sounds like you have incompatible components.

Shimano shifters had the same cable pull for MTB and Road varients all the way up to 9sp, meaning that the rear mechs had the same cable pull so were interchangeable (rear only, the fronts have been different for a while). Then Shimano changed the actuation ratio of their 10sp MTB mechs so they only work with 10sp MTB shifters.

The Shimano Road mechs still have the same actuation ratio as before, so a standard tourer's way of getting round the issue is to use a 9sp Deore rear mech with 10 speed road shifters.

Why they decided to change something that worked well is beyond me, but I guess with the longer GS road rear mechs reaching 32t they decided that there was little need for mixing and matching.
 

Drago

Flouncing Nobber
Location
Poshshire
Yellow saddle is correct. Shimano MTB and road gear are cross compatible for indexing purposes up to an including 9 speed. 10speed differs twixt the two with different pull ratios, the MTB having a fractional rising-rate in the ratio on the lower gears.

In short you either need Shimmy 10 speed mtb shifters, or a shimmy 10 speed road mechanism. Like with like.
 
OP
spennie

spennie

Über Member
I've been looking at shimano rear mechs, shimano only do the road mechs with a medium cage, but i'm not sure if this would be ok with a triple front and a 12-32 cassette
 
Location
Loch side.
I've been looking at shimano rear mechs, shimano only do the road mechs with a medium cage, but i'm not sure if this would be ok with a triple front and a 12-32 cassette
All derailers have a maximum capacity which is measured in "teeth."

1) First figure out what capacity you require. The formula is as such, for your desired setup: (32-12) + (size of large chainring minus size of small chainring.). You'll end up with a number that has to be smaller or equal to the derailer's maximum capacity. This information is published on the derailer company's website.

This is not to be confused with the maximum size of the largest rear sprocket. This is another limitation that should also be adhered to for perfect shifting but like all things, we tend to push our limits.
 
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