K2 / Proflex Riders Group

General => Tech Forum => Topic started by: dhingle on February 16, 2009, 06:49:34 pm

Title: unwanted shifting of gears
Post by: dhingle on February 16, 2009, 06:49:34 pm

i have another question.  what causes the bike (beast) to shift gears when i am climbing hills or hitting rough terrain.  i am assuming it is from the shock compressing and something not right w/ cable to rear derailler either too much or not enough slack in cable?

Title: Re: unwanted shifting of gears
Post by: Colin on February 17, 2009, 03:07:57 am

yeh, either the cable outer run is too short or the inner is cruddy and as the suspension moves it is causing drag on the gear cable causing the RD to move to the next cog.

replace the whole gear cable and outers with a nice Shimano XT kit, http://www.chainreactioncycles.com/Models.aspx?ModelID=1594 (http://www.chainreactioncycles.com/Models.aspx?ModelID=1594) ensuring smooh curves on the outers throughtout the suspension movement (look at an original marketing photo of your bike to get an idea of the right curves.)
(http://www.chainreactioncycles.com/Images/Models/Full/1594.jpg)

Check the RD isn't knackered and has loads of slop in it or the jockey wheels, 'cause that might also affect things.

I did a complete drive train rebuild on my 4000se and it was sweeter than my riding mob's brand new bikes! They say they couldn't even hear me change gears! <GRIN>

Col.

Title: Re: unwanted shifting of gears
Post by: Thunderchild on February 18, 2009, 12:02:43 pm

My 5000 did this when I replaced the cable housing between the frame and swingarm and cut it too short.   

Thunderchild

Title: Re: unwanted shifting of gears
Post by: dhingle on February 18, 2009, 02:41:39 pm

i have a new piece of housing i am going to try.  thanks for suggestions.

darrell

Title: Re: unwanted shifting of gears
Post by: Matno on February 18, 2009, 08:51:52 pm

1/4" too short is enough to make a huge difference. Been there, done that.

Title: Re: unwanted shifting of gears
Post by: craiga on March 06, 2009, 04:51:17 am

This is specifically mentioned on Sheldon Brown's web site.

He says that people forget to maintain the cable run that goes under the bottom bracket & through the holder on the frame under there. This gets dirty & as the frame flexes under heavy load, ie climbing, the cable sticks & gets pulled, thereby changing gear.

A bit of a clean & some lube under there & it cured the problem on my XP-X

Title: Re: unwanted shifting of gears
Post by: dhingle on March 10, 2009, 07:37:52 am

the cable on my beast doesn't run under the bb and i just had cables replaced at lbs a few months ago.  can't find a picture to see how much bend in cable is enough so is there a such thing as too much?  also on another note, just got my risse racing shock back after 2nd time being sent back due to oil leaking, rode last night to check it out and have light coat of oil on piston after ride from compressing.  since this is first air shock is this normal?  at least it wasn't dripping off the shock like in times before.

Title: Re: unwanted shifting of gears
Post by: orange on March 10, 2009, 02:00:20 pm

shouldn't really be any oil from my limited experience, bar maybe a *very* thin film