Author Topic: shifting problems  (Read 1850 times)

Mahk

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Re: shifting problems
« Reply #15 on: September 16, 2013, 12:51:43 PM »
Thanks for all the replies. 
 
Just to clarify--I asked a shop to, among other things, replace both the cassette and the chain about...mmm 5-6 weeks ago.  I was still having problems, so, about a week and a half ago I went to a another shop and they said that the chain was not a good one, was worn, and suggested that it be replaced.  Even though the chain was only 4-5 weeks old I thought they may have been right because when I wiped the chain with a rag I could feel nicks and burs that caught on the fibers of the rag.  I don't know how long a chain should last, but I am riding about 100 miles a week, more some weeks, so that would mean the chain had about 400-500 miles on it.  Seems it should last longer than that. 
 
The hanger seems a likely culprit.  I've crashed a couple of times.......well, several times.........ok, a bunch, which could have bent it.  Also, I've looked at other bikes and talked with other riders and they seem to be handling the dust without any of the issues that I am having. 
 
Thanks again for all the input and offers.
« Last Edit: October 05, 2013, 03:31:27 PM by Mahk »

chuckdlou

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Re: shifting problems
« Reply #16 on: September 16, 2013, 12:58:35 PM »
i had a chain on a rocky mountain pipeline that lasted well over 5 years and had 7 powerlinks in it by the time i broke the frame on the bike...

tony

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Re: shifting problems
« Reply #17 on: September 16, 2013, 01:26:31 PM »
Just curious, are you avoiding being cross geared?  Talking about being in the large chainring and the biggest cog, or the smallest chainring and the smallest cog?  There are certain combinations that just won't work that great.

At TRTP, I often see riders roll up in the biggest chainring and biggest cog...

Mahk

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Re: shifting problems
« Reply #18 on: September 16, 2013, 08:10:53 PM »
Yes, I avoid cross-gearing, but I'm not sure about the terminology.  Chainrings are front, and cogs are back? 
 
The bike has three chainrings, 9 cogs, but I rarely use the big chainring.  The other two have some overlap between them, so when I am in the middle cogs I may be in the middle or the smallest chainring.  But, when I am at either end of the cogs I always try to be in the corresponding chainring. 
 
TRTP??

Raleighguy29

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Re: shifting problems
« Reply #19 on: September 16, 2013, 08:20:45 PM »
The only time I've ever had shifting problems is once when I zip tied my hand pump to my top tube and pinched the rear shift cable. Or when I've bent a hanger. Funny about chains. My hard tail still has the stock chain on it at about 1300 or so dirty ruff miles. I broke the frame before I broke the chain. But the first time I took my stumpy to bcsp in February it had about 30 miles on it and the chain broke before I got to hp.
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David Kuehnen

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Re: shifting problems
« Reply #20 on: September 17, 2013, 08:12:12 AM »
Agreed, the last bit of cable housing nearest the rear deraillieur can cause a lot of shifting problems.  A bit of fraying at the end will allow it to move around relative to the ferrule which will play havoc on shifting. 

The only time dirt in the cable has ever been a problem was when using the old looped cable casing (i.e. the long cable housing that did a 180) from the seat stay tot eh rear of the derailleur).  if the radius was too tight, a little dirt in it could really make it difficult to shift.
« Last Edit: September 17, 2013, 10:04:07 AM by David Kuehnen »
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Kswiss

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Re: shifting problems
« Reply #21 on: September 17, 2013, 08:38:33 AM »
I ran into an issue with my Full Suspension that would always give me fits until I solved the issue.  When the bike was put together the cable and housing were not long.  When it was up on the bike stand it was fine, but when I was on it it stretched the cable out and made it shift.  It was only short by a few cm, but it still makes a difference. 


So my suggestion is to verify that your cable is long enough.

David Kuehnen

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Re: shifting problems
« Reply #22 on: September 17, 2013, 10:01:57 AM »

 
.....TRTP??


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other  acronyms you are likely to see on this forum:


BCSP - Brown County State Park
VSP   - Versailles State Park
SWW - Southwest Way park
David Kuehnen, PE

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Mahk

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Re: shifting problems
« Reply #23 on: September 18, 2013, 01:59:54 PM »
I spoke with the shop that last worked on the bike and they confirmed that they did check the derailleur and hanger and they were fine. 
 
At this point I think I will wait until the Breakdown and speak with the Trek rep.  Hopefully s/he'll be able to determine what is causing the problem. 
 
Thank you for all of the suggestions. 

Raleighguy29

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Re: shifting problems
« Reply #24 on: September 18, 2013, 08:58:39 PM »
Oh, see there's your problem it's a trek.  ::)
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Mahk

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Re: shifting problems
« Reply #25 on: October 05, 2013, 02:42:17 PM »
I took the bike directly to the Trek tent on the vendor/demo day (Saturday) at the BCB.  Trek's head mechanic suggested silicone cables and kindly installed one for me while I waited.  I did a short test ride (North Tower Loop and Pine Loop, about 5-10 miles) on Saturday and the cable worked ok, but not flawlessly.  The few glitches could have been attributed to the fact that I hadn't cleaned or lubed the drive train after my last ride, and both the cassette and chain ring were still very dusty and dry.     
 
On Sunday, however, despite a good cleaning and thorough lubrication, the new silicone cable quickly succumbed to the incessant rain and ubiquitous mud (and I had a ton o' fun!!!).  Shifting was completely unreliable and I am still uncertain what is causing the problem.  Shark told me about a different chain lube and I am going to try that. 
 
Thanks again for the suggestions. 
« Last Edit: October 05, 2013, 03:32:12 PM by Mahk »

DeepVI

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Re: shifting problems
« Reply #26 on: October 05, 2013, 03:03:03 PM »
I'd still be really surprised if it's a lube issue.  I'm really bad about lubing/cleaning my drive train and it has yet to cause anything other than accelerated wear.
Can't remember if it's been mentioned.  Have you checked your pivots?  If they are a little loose and flexing, that could also cause some ghosting shifting.  It could possibly be your RD as well.  Maybe the pivots are worn and causing slop, as could the tension spring be worn out.  If you can get your hands on a loaner, it might be something else to look at.
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AL

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Re: shifting problems
« Reply #27 on: October 06, 2013, 03:24:47 AM »
You mentioned your chain was damaged and marred after a few hundred miles.  You may want to inspect your front chainring for a damaged tooth or ramp.  While a bad tooth can cause chain skip on the rear cog it would not explain the chain problem you have moving up and down the rear cogs.  Like others have said that sounds like a cable tension or limit screw issue.  However, poor shffing under power can damage chains and chainrings.
Im with the previous poster DeepIV, that you may need to try putting another rear mech and or shifter on.  Even a used or borrowed one to help figure out whats going on.  I wouldnt spend money  on new parts tell you get it diagnosed. Also, search your make and model and year of bike on the mtbr.com forums.  Maybe others have had cable routing issues.  Even the big bike makers have design issues/flaws.  In the end it maybe best to take it to a good mechanic.  Ask others in your area who is a good bike mecahnic who knows how to work on full suspension MTBs.  Its really hard to diagnosis and fix these problems over a forum there are just too many variables.
Good luck!
« Last Edit: October 06, 2013, 04:07:27 AM by AL »

Nate Hawkins

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Re: shifting problems
« Reply #28 on: October 08, 2013, 05:51:27 PM »
My shifting was nearly flawless with Gore Ride-On cables/housing that are probably older than they should be.  My wife's shifting was spot on with XTR cables/housing.  High end cables and housing really are worth it, IMO.  I won't ride anything but fully sealed or full housing on my bikes from now on, due to the reliability of the Gore cables.  Unfortunately, they don't make them anymore so I'll have to go with another brand.
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David Kuehnen

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Re: shifting problems
« Reply #29 on: October 08, 2013, 06:22:17 PM »
Have you considered that the shifter itself could be the problem? reading back through this thread, I did not see it addressed.   It is the "brains" of the operation. and may be the cause of the problems.
David Kuehnen, PE

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