Tight cable bends - bad shifting?

trek_dan

The shifting on my newly assembled bike is ok but not as crisp as I'd like, its Ultegra 6700 with a KMC X10SL chain. I think its safe to say its all setup ok as the Ultegra 6600 stuff on my winter bike was also setup by me and works perfect. The shifting just feels a bit vague and delayed. The only thing I can think to put it down to is how tight the bend is on my Deda Presa carbon bars, the cable hangers seem to put a really tight bend into the cables. Is this something anyone has experienced before or could it be something else? Its setup with the standard Shimano cables that came with the 6700 kit, would changing to a better cable help?

sungod

tight bends will increase friction, it's certainly possible - but i'd check things like rear mech adjustment, hanger alignment etc. as well

if you release cable tension and peel back the hood, you should be able to pull the cable out from the shifter a bit, then use fingers to move it back and forth to see if there's a lot of drag

Monty Dog

Modern gear systems are very succeptible to friction and cable drag - particularly the new shape of Shimano STIs with under-tape routing combined with tight-radius compact bars. If you have a short stem / headtube try routing the cables around the headtube and crossing the cables underneath the downtube - it looks neater and minimises cable rub too. I'd also unwrap the bar tape to see if it makes any difference.

migrantwing

Monty Dog wrote:

...try routing the cables around the headtube and crossing the cables underneath the downtube - it looks neater and minimises cable rub too.

Excellent advice. I follow this procedure.

Bozman

I've got 6700 on one bike, I've swapped the cables, avoided tight bends and it won't improve the shifting because Shimanos first attempt at hidden cable is shite, 6600 and 7800 are head and shoulders above 6700 and 7900, lets hope that the 6800 and 9000 are a step up.