Friday, July 06, 2007

Single Run Rear Gear Cable

There have been times when the gears on my 5-Spot have worked flawlessly, but mostly they have been unreliable.

I remember when I first bought the frame reading about people who drilled out the cable guides and fitted a single run of cable to the rear mech. This did seem drastic but after our Scottish trip and more problems :-( David suggested I try this solution by using disc hose guides.

The problem was that these were far too big for gear cable, but I decided that cable end caps with the ends cut off could be used to tighten up the fit.

So, the conversion was done, not the neatest looking run of cable, but it would do for now.

Just in time for the midweek trip to Cannock, a 20 mile trip with varied terrain and no doubt some mud after the recent rain.

Despite the fact that there had not been time for it all to settle in, for the first time ever I experienced clean and accurate changes, I could not believe the difference :-)

It would be wrong to say all was perfect as the cable guides were still not a good fit and with suspension movement the cable would sometimes pop out of its location. So perhaps a little tinkering to tighten things up, or maybe I will pluck up the courage to go the whole hog an drill the frame guides out. Certainly a worthwhile mod on a full suspension bike.

6 Comments:


Farqui said...

Excellent news, now you'll have no excuses for not keeping up ;-) Only kiddin', it's often us that struggle.

Although I've not gone for 100%
full cable outer, I've found that both enclosed systems I've used (Avid Flak Jacket, Flying Snake) made a big improvement to shifting reliability Without enclosing the rear section, the cable gradually clogged with grit, slipping in thru the last cable stop. A particularly bad case, had me struggling to remove the outer as it was jam packed with grains.

I also found the long narrow XTR-like cable ends helped reduce the ingress a little.


Rob said...
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Rob said...

Joffers, sorry to hear you still have your gear shiftin Gremlins. My blood runs cold at the thought of drilling the frame guides so perhaps my experience might help.

I use stock Shimano outer with XTR Teflon coated inners and ferrules. In 18 months+ with my flux I have had flawless shifting with one exception. The rear was going wayward, uh oh I thought, new cables required, on removing the outer from the shifter end I discovered parts of the shifter inside the cable outer!! A small piece of unidentifiable plastic and a tiny rubber O ring.
I was amazed by this but on reassembly all seemed to work fine except it would suddenly adjust itself half a gear one way or t'other. New 07 XT shifters cured the problem compeletely.
Now perfect instant flawless shiftin again.
The reason I say all this is not to gloat but to demonstrate your problem is not intrinsic in the frame. I know Farqui has had some difficulty but on the whole his 5 has been the same.
The evidence of using a single run of outer and it working properly is compelling I agree but it may just be the small improvement in one area is enough to take it from no work to work.
Shifters are one of those parts that we all assume either work or they don't, this is not true. Also I have had cassettes that would not shift well whatever I did, I have no clue how the cassette can do this but there you are.
I have tried Avid, Flak Jackets and so on, unusually for me the bling look did not cover up the fact that on the whole they make no difference and cost a lot of money. Stock Shimano + XTR cables perform better and much much longer. In general I recable my Flux every 2 years or so and even then the rear inner is reused in the front. I wouldn't consider any other cable type.
Step away from the Black and Decker, that sort of vandalism can't be the answer.
I would suggest you invest in some tape and tie wraps and ride it as is for a while, wait and see if the same gremlin creeps back in. Then you'll be proper sure.
BTW, if you do drill it, don't forget 6k alloy frames are heat treated (400degC), you need to keep the metal cool and the bare metal after drilling will corrode. Use your nail varnish to recoat the metal but not that bright red shade you normally wear.


uphilla said...

Rob, thanks for the advice, I must admit that my 'experiment' was very unscientific in that I took the chance to change my shifters at the same time as the cable - so theoretically it could be the shifters that have affected the quality of gear changing. Time will tell, I guess, but past experience of changing shifters suggests that such a big difference must be down to the cable run.
I am going to stick with the adapters for now, but I read that Specialized are now using a single cable run on some of their new bikes.


dozer said...

My Endozer came with single run gear cables and I have not had any problems with my shifting. Although maybe that extra weight is what is slowing me down :-)


Rob said...

Joffers,

There is one thing that might help you. My Jekyll has only cable guides for single run on the triangle. I don't use single run however, it's fitted with removeable cups that the cable ferrules fit into. About 15mm long 6mm o/d and 4mm i/d they have a lip so the cable tension holds them in place.

If you can source some of these you could drill your frame, then if you want to change back fit these.

I guess a Cannondale dealer could supply them, these were originally fitted to a 2001 Jekyll frame but the 2nd frame (it broke) also had them and was 03 vintage if I recall. My next guess would be Answer products (magura) they do all sorts of twiddlies.

The other thing I discovered recently was my flux gear hanger with a loose bolt. I assume you checked yours? I think we have a spare somewhere between us if you needs it.

Dozer; Enduro is fitted with single run cables cos it's intended for rough stuff, the open cable ends are a problem. The problem with single run apart from the weight and the cost of fitting it is there is far more cable drag and in the long term it will perfom worse. XTR mech helps as it has greater spring return force than XT and it's also adjustable.


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