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Shifting prob, right cable housing?(9 posts)
|Shifting prob, right cable housing?||Woof the dog|
Nov 7, 2001 9:37 PM
|My problem: It shifts, but I seem to constantly have to adjust the derailure tension to get a better upshift. Cable is old, in one place where it goes under a chainstay, it has a tiny bump = single cable thread is probably loose or something. But cable itself is tight on the derailler, so it doesn't seem to be slipping. Shifting works - smooth on shifting to a larger cog, except for one place from 14 to 15. Weird! Maybe a defective cassette bought from Supergo for such a cheap price? In any case, what concerns me is two thing. First, when shifting to a smaller cog, lets say from 13 to 12, under power when sprinting or just pushing hard on chain it jumps on that cog real sudden making a real jerk on my chain and consequently my legs. I am afraid of snapping a chain like this. It simply sucks! Whats the deal? Second thing: Could it because LBS used break cable housing instead of shifting cable housing for rear shift system? They said it makes no difference and they built a number of bikes with thicker housing like that. My shifter is Dura-Ace too, so it should work fine, 6 months old. Any tips would be appreciated. Sorry for a long post.
|re: Shifting prob, right cable housing?||cyclaholic|
Nov 7, 2001 10:04 PM
|I've had a similar problem in that in downshifting from my 14 to my 15 cog, the derailleur would not shift. All other downshifts were good. The problem was a severe fray in the cable where it passed through the cable guide. That may not be your problem, but make sure that when you downshift, the cable is free to pull cleanly. Even a small fray could be adding resistance.
I don't know about the upshift problem. Some messiness is to be expected when hammering and upshifting, but yours sounds extra bad.
The cable housing could be an issue, but first I'd make a really good examination of that cable and rule it out as the culprit.
|re: Shifting prob, right cable housing?||brider|
Nov 8, 2001 6:36 AM
|There is a difference in size between brake and shifter cables and housing. Also, the holes in the frame cable stops might not be large enough to allow for free movement of brake cables. You're using Shimano STI, right? The cable housing going into that shifter HAS to be shifter cable housing, which wil have a too-small inside diameter for brake cable. I'm thinking your LBS sold you a bill of goods.|
|re: Shifting prob, right cable housing?||Winnebago|
Nov 8, 2001 6:55 AM
|The problem is very simple, first things first though, you need to get a new derailleur cable and second, most definitley the cable housing needs to all be SIS index housing. As a sponsored person of Shimano, Park Tools, and Spinergy, I have had many issues such as this. As for the skipping of the chain, there is a tool that Park Tools makes called a chain checker. This checks to see if your chain has stretched, and ANY time you put a new cassette on, you should alway's put on a new chain. The chain could also be the reason you have trouble shifting from your 14 to 15. One last thing, when you put your new cable and housing on, make sure you lube the cable before sliding it through the housing.
|replace the the dX wire & cable housing ...||breck|
Nov 8, 2001 7:28 AM
|don't wait, do it now :) |
Somewhere hidden where you cannot see, one of the individual wire strands may have frayed or broken, therefore causing the up-shift under tension problemo, i.e, the dX wire bundle stretches a tad under tension.
Down shift problem may be caused by same broken or frayed strand aided by excess friction within the cable housing as the dX wire rubs and the lube has gone away ( if any were put in it in the first place) due to old age, etc. This can be very intermittent due to uneven tension & binding throughout the ride conditions.
Last but not least Seek out a LBS that will match the cable housing with the dX wire as a unit. If you replace the dX cable housing/ dX wire yourself, drip some Tri-Flow or sim to oil thru one end of the the cable housing till it exits thru the other then twirl the cable housing a bit to get the excess out.. Put some bicycle grease such as Pedro's, etc. on the dX wire and wipe off excess. Install and adjust. Should shift perfectly if the chain, and or/ cog set is not worn, etc.
Typically the shift dX wire is 1.2mm & brake wire is 1.6mm. This is ~78% diff in area, so would always insist on matching cable housing and wire, etc.
Have the new LBS (or you) replace the front shift wire and correct cable while you are at it. Less non-recurring labor, etc. :)
|2nd the Idea||grzy|
Nov 8, 2001 2:07 PM
|You simply can not believe how much of a difference it makes to replace the cables and housing. While riding lots of gunk works it's way inside the housing. Even if every thing looks fine you can have enough corrosion on the cable or have worn through the plastic liner inside the housing to make everyhting very sluggish. I used to wrestle with this by just replacing one or two elements - now I just replace the whole works. Shimano makes a white lube that works well as well as Slippery Spit. Having nice smooth running cables is required if you want good shifting. I used to save all of the odd bits of housing for spares, but now I just toss it all - otherwise it's sort of like saving used dental floss.|
|here is what I did||Woof the dog|
Nov 8, 2001 8:06 PM
|First of all, thank you all very much. You are simply the best. LBS has some mtn. biker types (in their 20s) working on bikes. These young mechs say brake cable housing is fine on many bikes they built, while old guys in the shop say its not. Funny shit. Another reason I will never leave my bike alone with a mechanic who is younger than ~40. Just plain dangerous with how they treat the bikes (jam chains, hit frames with all sorts of tools) They do get the shifting right though.
I replaced housing and cable with the right ones: durace housing for shifter cables + Jagwire slick der. cable (stainless, prestretched, best one according to an old LBS guy, is it really so? maybe he meant that was the best one available at the moment. Either that or I could get a Campy cable for 10 bucks...hmmmmmm.......) It did seem to make quite a bit of a difference, but it still drops the chain into a smaller cog too jerky and fast..not as smooth. Tried to adjust that with cable tension. i.e. I tried both "limits": where der. is moved inward but still shifts fine from say 17 to 16; and where there is just enough tension to bring chain back up to a larger cog but plenty to throw it back down. Seems to make no difference - chain still drops down a bit too jerkily for my taste. Can I smooth it out with a higher limit screw? Maybe I am too picky.
I guess I put on some serious miles on this cassette and chain after I took my computer off. Chain, to my surprise, is stretched by 1/16th of an inch, which is fine although out there! Amazing how much Prolink I used on this baby, but I guess milage finally caught up. I am gonna replace it anyway tomorrow. I might as well get a new cassette. Or is it not necessary?
Thanx for your help ppl.
Woof, the Honey-producing Bee.
|rear dX adjustment ...||breck|
Nov 10, 2001 12:45 AM
sorree had to go down the mountain today & thought you would have got sum input, etc. Not to familiar with the new "Jagwire", but do recall the old XKE that one could drop a 289CID Ford into and make it really run :) Anywho the following is my best shot at you getting better shifting from the new chain. Others may want to join in and add to; subtract from, etc. Always larnin' :)
Re: new cassette, if you got the bucks do it :) Easier in the old daze when you could un-pin the cog and replace each cog by itself or customize the block cog by cog. My first Shimano 8-speed XTR spider yoke cluster block the cogs had screws but now riveted both road and mountain. U-R stuck :)
On the serious side the purpose of the A & B limit screws are to limit the guide pulley so that the chain does not go into the drop outs on the small cog side nor into the spokes on the big cog side. It doe not figure into tension of the derailleur to move the chain up and down the block, etc.
After you assemble the new chain try the following.
1) Looking from the rear, adjust the top limit screw so that the guide pulley is below the outer line of the small rear cog (outside of cog towards drop outs, not centerline).
2) Connect the dX cable wire to the rear dX and stretch the cable by pulling outward from the down tube, then reconnect the rear as this should have caused a small amt of slack.
3) Shift to the biggest rear cog and adjust the bottom limit screw so that the centerline of the guide pulley lines up with the center line of the cog (not outside this time :).
4) With chain on smaller chain ring and cassette biggest cog (freewheel) adjust b-tension screw close to the gear but not touching. Likewise, move to the chain to the smallest cog and adjust same.
5) **Now here is where you will adjust proper indexed shifting** You may need a bike stand, etc. With chain in the big ring and rear smallest cog make one rear cog up-shift. You are now in the second rear cog. Whilst turning the crank forward slowly turn the rear dX adjusting barrel counterclockwise (more tension) till you hear it rubbing on the third cog. Back off a tad clockwise till silent smooth :) Now shift up and down the block and make sure no problemos. Note that turning the barrel counterclockwise will always make the chain move up the cluster towards the wheel; clockwise down the cluster toward drop outs.
6) On Shimano there is one other adjustment bolt called Spring Tension & can be set to strong/ weak that sets the tension in the guide spring. If higher return force for the rear derailleur is desired, set to strong; less return force set to weak. This is under the dX body and has blade screwdriver slot.
& etc) In general after XXXX miles & cable stretches & there is prob shifting up you need more tension and therefore turn the barrel (not much at any one check) counterclockwise to tension the cable a tad more. If after shifting chain rubs on the next up gear, turn the barrel clockwise a tad, etc. In the for-what-its-worth cat i always park my bikes with the chain in the smallest chain ring/ smallest rear cog positions.
One thing you may want to do before attaching the rear dX wire is to run the barrel adjuster all the way in and all the way out and count number of total turns. Then turn barrel one half that count to center the barrel before attaching the wire & adjusting, etc.
RE: Woof, the Honey-producing Bee.
Sue Bee sez, "Don't say Honey, say Burleson!"
...old ft. worth texas burleson ad back in the 50's.
|rear dX adjustment ...||Woof the dog|
Nov 11, 2001 12:52 AM
|cool thank you, I will have this in my records.
Woof, the Maple Syrup dawg