i use a short cage shimano 105 on my DH bike, it reduces the chain slap and its has more stiffer spring! the trick here why the pros use small cage? MTBIKES cassettes are a little heavier on road cassettes, ryt? cause they are small yet strong. its a set up thingy! to save weight on thier DH bikes. first, a dura ace sprocket, 2nd, small chainring around 40tt, to compensate on the small cogs then short cage roller for less chain. even thou u use small cogs, u must know whats pedaling capability.. ur power to weight ratio of the rider.. its not just about the short cage issue.. but a whole set up issue! i use a 105 roller but a deore 9speed cogs n race face 44tt chain ring... it is because i havent finished the whole set up.. in time ill be using the 40tt chainring ang road cogs... to reduce weight and good pedaling cadence.. at DH runs.. its better to spin than to grind the cranks!!
Post by atomikmatchbox on Mar 28, 2005 8:13:56 GMT 8
frorider is ryt ;D now for the set up thingy mention by pengot, looks like i need to change my whole bike hebigats kasi, set up of dh bikes here in phil. are pagaangan na and im left behind more on redbull rampage ang set up ng bike ko i need to save money again for new dh rigs
peachy is right. shorter cage for small road cassettes and longer cage for bigger mtb cassettes.
i recently replaced my XT deraileur with Shimano 105 using mtb XT 9-speed cassette but i couldnt run the bigger (light) gears (#32 & 28) because the upper pulleys kept hitting the cassette. In the end, had to kill the #32 gear and replace the screw thats screwed against the drop-out (dunno what this is called) with a longer one to keep the pulley from hitting the #28 gear.
i shifted to a short cage deraileur so that it would have lesser probability of getting entangled with my spokes.
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Post by nightcrawler on Mar 29, 2005 20:37:08 GMT 8
is it for clearance to avoid roots or rocks? or is it for shortening the chain to minimize chain flopping during a dh run? to save weight?
yup all of the above. plus it shift smoother.
why is there a short and long cage derailleur? in the first place, and why road bikes use the short derailleur?
There are also long cage front and rear derailleurs for Road bike. This is if you will use a tripple chainring in front. Yes their is a tripple crankset for road bike. So that explains it, if you have tripple chainrings you need to use longer rear dearailleur to compensate for the extreme tension when you use your big chainring and big sprocket (this is not advisable though). I'm exaggerating so we can picture out if you use a smaller rear derailleur..........
In DH we have only 1 chainring so I guess if you can picture out what i describe above, a long cage is an overkill for DH. Thats why they make Short cage for MTB rear derailleurs - for DH.
can we use road bike short derailleur on 8 or 9 speed mtb sprockets? (compatibility issue) and what will be the perfromance?
Most definitely... try checking out at the races you can see people running this set up. I have 105 RD, xt 11-32 cogs and 40T front. This is my set up for the longest time.