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Rear derailleur mystery - Help please
Help please.
Last week noticed my rear (LX) derailleur cable hanging way out at right angles and the outer braid was broken. I assumed I had snagged it on something as the cable had been pulled back from the bars and got it replaced. (Which was expensive after the tune et al.)
Just back from a ride with a new inner and outer cable and the same thing just happend - noticed it was pulled back after one rough fire trail section with no chance of a snag. By end of the ride the outer braid was broken. Has been working fine previously 12+ months now. Happy to upgrade to an XT shadow that removes that big ring of cable but want to ask if anyone has had similar issues to try and figure out why.
The only thing I can think of that's changed is that I am using more large front ring & top gear than before and I do hear a lot of derailleur slap against the frame??? Or the spring in the derailleur has gone soft and its flopping about?
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The cable outer which is plastic, ages and gets brittle over time. When it is cut to length 'old' outer will crack slightly lengthways with the cable.
The force of changing gears (and maintainig tension) can result in the 'old' cable splitting from these cracks, and the steel strands can push through.
Cheap cable outer is particularly prone to this. The replacement cable you used could have been old stock or the lesser quality stuff.
I'm reminded of this situation, as last night I was fitting a new rear der, and replaced my cables at the same time. I'd got some xt level cable some time ago, and even though I was using my nice sharp Park Tool cable cutters, those tell-tale cracks appeared at the cut. So, I had to dig out something a bit newer.....
It is not uncommon for sticks to snag the cable either. Getting the loop short enough without affecting gear changing is a fine balance. The shadow ders do have a far more protected cable path, and are less prone to snagging too, just like SRAM.
Whisperer
FWIW I have literally just broke my XT Shadow (12 months old) about 30 mins ago up at the Dam. Luckily it was 200m into the ride and I could freewheel all the way back home into Da Vale. Basically the P-Tension Spring has gone on it. After chatting with Hamo when I got home he told me that the Shadows are quite notorious for this to happen. It happened to him up at Coffs in a race.
I'm not too pi**ed about it though as I have just ordered a spare XTR Rapid Rise from CRC which shipped yesterday so I shouldn't be too long off the bike. Maybe my XT derailleur caught wind of the new part and gave up all will to live. Who knows.
Any way just thought I'd give you my experience pretty much straight off the trail.
Oh and the XT is a very noisy beast too, lot's of chain slapppp.
Phil
I'm changing probably twice a year. I keep a few metres in stock in the workshop all the time.
AS soon as the shifting gets vague the sectoin down by the RD gets swapped out for a new bit - and this is with XTR outer.
I'm considering going Nokon or Goretex.
Tips:
* change to the big ring going down hill - reduces chainslap.
* Wrap a dead tube around your chainstay for protection.
* I also have a short section on the seatstay on the dually as well, but it wasn't required on the HT.
I'm quite happy with my XT rapid rise.
BTW, the rumour is XT and SLX both go 10-speed next year.
Thanks for the headsup - Confused on which one to buy - Rapid rise, long cage, low normal - Checked out CRC THE XTR for $100 is a bargain - But which vers?
Rapid Rise = Low Normal. When you tap the trigger it goes to an easier gear instead of a harder one like SRAM and High Normal shimano.
Much more intuitive than high normal, where you're pushing against the DR spring to change down. Compare downshifting while you're on the brakes between the two and you'll see what I mean.
Go long cage if you have a triple on the front.
I got the derailleur that matched my XT shifters (RAPIDFIRE).