short cage deralier with mtb casette

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edwin veal

Likes Dirt
i have just recently bought a 105 rear deralier and also a mtb casette but when i first tried to fit the casette the derailer hit in first gear.
has anyone had this sort of problem before and if so how did you fix it?
i was thinking i could go and get another hanger cnc machined but i was wondering if there is anything else that can be done.
thanks for any sugestions
 
Daver

Daver

Kung Fu Panda
adjust the p-tension until it doesn't hit, and make sure the cassette is smaller than a 28 tooth big cog
 
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edwin veal

Likes Dirt
i found several referances for an 11 28 but have heard varying results about them
but your probably right i might have to swap the casette over to something else
what would you think of getting a new hanger machined?
 
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Rik

logged out
Doesn't sound like a bad idea, but is it worth the time, effort and money?
you could almost do most of it by hand if you could be bothered, then just make sure the thread is drilled and tapped dead straight.
 
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edwin veal

Likes Dirt
i dont know wether its worth it so i am trying to guage what people think
i have seen 105's work fine with a wide block but some hangers are different
 
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lupine128

Likes Bikes and Dirt
i try and never allow a road derailier to be used on anything bigger than a 28 if it can possibly be avoided.
the road or short cage derailiers are only designed to have so much extension in them. more than a 16 or 17 teeth spread in total will over extend the the mech, and it will break. sooner or later, and probably sooner cause it's not meant to do it.
you will also have clearance problems because a road mech is designed with minimal clearance between the largest cog and the jockey wheel. the physical distance between the two is quite alot smaller than a MTB derailier. just adjusting the tension screw out will give you a little more clearance, but will make it a lot harder to get the mech to shift properly.
best bet is to work out what gear ratios you really use, and swap to a road cluster. then swap out the chain rings on the front (or ring if you run a chain device) to get the ratios you need. that way you won't eat your mech to often, and will have a more usable spread of gears to ride. it's a bit of stuffing around, but well worth the efort for the result.
 
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edwin veal

Likes Dirt
thanks you guys
i originaly wanted to get a sunrace 11-28 then couldnt get one so i had a look at the dnp in the same ratio but heard that the 11tooth breaks so i avoided that then my lbs recomended that i just stick a wide block on and now i have this problem
i came up with 2 ideas one being to make a new hanger and lenghtn it and the other is to make a braket that sits between the derailer and the hanger and sits on the stop for the b adjustment and gives me a bit more play with this adjustment
(sounds beter when you can see what i mean)
 
wombat

wombat

Lives in a hole
edwin veal said:
make a braket that sits between the derailer and the hanger and sits on the stop for the b adjustment and gives me a bit more play with this adjustment
(sounds beter when you can see what i mean)
Click to expand...
Wouldn't it be simpler just to get a longer p-tension screw? Of course, either way you'll risk placing excess tension on the spring.
 
bazza

bazza

look at me
i have just locked my tiagra rear deraliur out of the top gear, and if she starts playing up after that i lock it out of the next highest gear. it works. she is starting to creak pretty bad atm though.....time for some attention. but yeah, you usually dont need your top gear anyway so just lock it out and save your deraliur the trouble.
 
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edwin veal

Likes Dirt
lupine128 have you ever had any experiances with a short cage breaking like that?
All the deralier needs to do is have the side to side range (wich it does) and if i am making a new hanger the only abnormal stress is placed on the hanger not the deralier as it is doing its normall job and because the new hanger is made of steel not brass it will take the stress
 
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Rik

logged out
A steel hanger? :shock:
I hope you enjoy the sound of a derailleur being ripped off... even if you do offset it enough to fit a 32t cog, there's still risk of things going pear shaped.
 
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lupine128

Likes Bikes and Dirt
don't forget that a cerailier goes thru extension, as well as side to side movement.
i've seen derailiers come apart from both. mostly tho the return springs (which is what makes the damn thing work in the first place) just flog out and break.
i've also seen them come aprt at the cage joins because of over extension.
if you really want to do it, why not just go to a road bock at the rear and adjust your front chain rings to get the ratio's you want?
 
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