Bicycle Mechanics - auto shifting problem

I have a problem with autoshifting or slipping only when in the largest front ring and the smallest rear ring. I cannot seem to adjust this out. It only occurs about every 10-12 revolutions of the peda;ls then it slips into the second smallest rear gear. Bike is tandem with deore xt rear derailleur. Any suggestions on how to correct this?

Derailleur limit screw and/or shifter cable need tweeking. Also check to see if derailleur hanger is not bent.

thast quite strang for the gear your running id just do quick look over your bike to see if your chain has stretched and may be your xt needs to be adjuted. the rings coloud also be very worn to. Pop it into your local bike shop and they will fix that with no problems. i suspent a stretched chain

I have a problem with autoshifting or slipping only when in the largest front ring and the smallest rear ring. I cannot seem to adjust this out. It only occurs about every 10-12 revolutions of the peda;ls then it slips into the second smallest rear gear. Bike is tandem with deore xt rear derailleur. Any suggestions on how to correct this?

This is a cable tension issue, most likely. The adjustment is a barrel adjuster where the cable housing meets the derailer. Also, check your high setting limit screw. Full information is at link below.

Park tools drivetrain service (http://www.parktool.com/repair_help/FAQindex.shtml#drivetrain)

Doc

This thread sounds like a good argument for friction shifting. :)

lol it sure can be!

Interesting that you mention this - I've just started having a similar problem (road bike - double). Although things are okay in high and low gears, but in the middle (w/ small chain ring), it periodically starts jumping up and down gears. This chain has less than 1K miles (as does the bike). It's not spotless, but I only ride in crummy conditions on occasion.

I've also started using a trainer (CycleOps Fluid 2) in the last month or two - is it possible that the trainer might have bent the derailleur hanger? (how does one check other than buying one of those special tools?). I'll have to double check the cable...

Make sure your cable is not dragging too much. When the housing gets draggy, the upshifts will be slow or incomplete but the downshifts will be on still. The last section of housing is very prone to problems with that.

Interesting that you mention this - I've just started having a similar problem (road bike - double). Although things are okay in high and low gears, but in the middle (w/ small chain ring), it periodically starts jumping up and down gears. This chain has less than 1K miles (as does the bike). It's not spotless, but I only ride in crummy conditions on occasion.

I've also started using a trainer (CycleOps Fluid 2) in the last month or two - is it possible that the trainer might have bent the derailleur hanger? (how does one check other than buying one of those special tools?). I'll have to double check the cable...


Looks like it was just inadequate or maybe too much tension (cable seemed fine). After a bit of fiddling with it, it shifts normally now.

if you dont know how to fix some thing just fidil it always works

if you dont know how to fix some thing just fidil it always works
That HAS to be the WORST advice I've ever seen on here. When in doubt READ THE INSTRUCTIONS. How old are you anyhow?

The concept was fine, but quite haphazardly stated.

Don't fear your machine would be a better thing to say. But yes at all points possible, read the book they made for it.

im only 15 and when i have no instructions im always able to get it fixed

im only 15 and when i have no instructions im always able to get it fixed
That's why DARPA (http://www.scit.wlv.ac.uk/~c9814405/cp2014/howwastheinternetinvented.htm) invented the internet. Instuctions and guides abound here.

good your obsesive at being right but i give you that you are right. lol

sorry didnt mean good ment god

I had a similar problem fixed by by lbs. He did exactly what the The Fixer said...straighted the hanger, adjusted the cable tension and adjusted the limit screw. Now it works perfectly.