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MountainBikeReview.com's Forum Archives - Everything Drivetrain
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Short cage, long cage.........what works? (5 posts)
|  Short cage, long cage.........what works? | AndrewMcD
Jan 11, 2004 3:52 PM | | At some point I wanted a new rear derailleur on a bike so I told the LBS to go ahead and upgrade my XT to an XTR. They installed a short cage XTR derailleur that never shifted properly on my Specialized S-Works M4. When I switched back to the longer cage derailleur my shifting problems went away. I've still got that short cage derailleur in a box downstairs and I'm building up a new bike. What components are required to take advantage of the short cage XTR and make it work properly? |
| The cage................ | Mike T.
Jan 11, 2004 5:48 PM | | .....length has no effect on shifting. The only thing it affects is the amount of slack chain that can be wrapped up. |
| Yep, and I've had no problem using short chage on... | f'nætik (aka næstep)
Jan 11, 2004 5:56 PM | | ...11/34 cassettes with triple cranks. Just gotta remember not to shift into small-small. |
| The cage................so what's the advantage? | AndrewMcD
Jan 11, 2004 6:50 PM | | Is there any advantage to using a short cage? Why are they produced? |
| Andrew the cage lengths come with "rules of thumb", and as mentioned... | Bikeless Rider
Jan 11, 2004 7:37 PM | | ...mostly come into play when using certain gears. However, even though I have a fair amount of experience building bikes and generally don't use "extreme" gears, I was noticing some contact between my guide (upper) pulley of an older (about 3-4 years ago) XTR rear derailleur and the cassette (32tooth). The cage was of the more common "middle length" rather than their long cage model. What Shimano told me was that each cage length of derailleur had a specified cassette capacity, as the derailleur's mounting brackets were ever so slightly different between the two models, putting the guide pulley at optimum distance from it's intended range of cassette sizes. This meant that no matter how far I screwed in the B tension screw, there wasn't sufficient clearance between the guide pulley and larger (32 tooth) cassette. I got around this problem temporarily by using a longer, stainless screw, in place of the stock B tension screw. When I saw that the screw was slowly bending from the force on it, I decided to use that derailleur and a 30 tooth cassette on another bike, and get an XT long cage derailleur for the 32 cassette. Reasons like these are why SRAM designed their derailleurs to pivot more in line with the slope of the cassette's gears, eliminating the need for a B tension screw. I don't know if Shimano is still designing their derailleur brackets different for each cage length, but I know they still use the B tension screw, though as long as SRAM is an available option, I couldn't care less.
Don't mean to sound sarcastic, I just hate it when big corporations charge top dollar for overly complex designs, when quite often simpler ones result in an easier to understand and better functioning product for us "end users". |
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