false shifting when I'm on the trainer

I have a question for the more mechanically-inclined readers.

I'm having an issue when I hook up the new bike to my trainer. Not
long after I begin pedaling, I'm experiencing some sporadic false
shifting, meaning it both sounds and feels like I'm shifting, but the
gear doesn't actually shift.

With my pea-like brain, I'm assuming this is the result of either one
of two things. First, because the frame is a lot less stiff than the
aluminum frame I was riding, perhaps my weight is causing the frame to
flex once I set the rear skewer in the trainer and that, in turn, is
creating tension on the rear derailleur cable where it sits in the
cable guide under the crank housing.

Any thoughts on that one?

"Steve" wrote in message
ups.com...
I have a question for the more mechanically-inclined readers.

I'm having an issue when I hook up the new bike to my trainer. Not
long after I begin pedaling, I'm experiencing some sporadic false
shifting, meaning it both sounds and feels like I'm shifting, but the
gear doesn't actually shift.

With my pea-like brain, I'm assuming this is the result of either one
of two things. First, because the frame is a lot less stiff than the
aluminum frame I was riding, perhaps my weight is causing the frame to
flex once I set the rear skewer in the trainer and that, in turn, is
creating tension on the rear derailleur cable where it sits in the
cable guide under the crank housing.

Any thoughts on that one?


Which gear and is it when going down or up?
The adjustable screws or wire tension has got to be part of the answer.
If not low enough or high enough gear it is just the screws.

On Apr 12, 12:15 pm, "nash" wrote:
"Steve" wrote in message

ups.com...

I have a question for the more mechanically-inclined readers.

I'm having an issue when I hook up the new bike to my trainer. Not
long after I begin pedaling, I'm experiencing some sporadic false
shifting, meaning it both sounds and feels like I'm shifting, but the
gear doesn't actually shift.

With my pea-like brain, I'm assuming this is the result of either one
of two things. First, because the frame is a lot less stiff than the
aluminum frame I was riding, perhaps my weight is causing the frame to
flex once I set the rear skewer in the trainer and that, in turn, is
creating tension on the rear derailleur cable where it sits in the
cable guide under the crank housing.

Any thoughts on that one?

Which gear and is it when going down or up?
The adjustable screws or wire tension has got to be part of the answer.
If not low enough or high enough gear it is just the screws.

I'm not shifting when it happens--it just happens sporadically. In
terms of the gearing, it's a 10-speed and the chain is sitting on one
of the middle cogs in the cassette. When I ride on the road it
doesn't happen--shifts beautifully.

"Steve" wrote in message
ps.com...
On Apr 12, 12:15 pm, "nash" wrote:
"Steve" wrote in message

ups.com...

I have a question for the more mechanically-inclined readers.

I'm having an issue when I hook up the new bike to my trainer. Not
long after I begin pedaling, I'm experiencing some sporadic false
shifting, meaning it both sounds and feels like I'm shifting, but the
gear doesn't actually shift.

With my pea-like brain, I'm assuming this is the result of either one
of two things. First, because the frame is a lot less stiff than the
aluminum frame I was riding, perhaps my weight is causing the frame to
flex once I set the rear skewer in the trainer and that, in turn, is
creating tension on the rear derailleur cable where it sits in the
cable guide under the crank housing.

Any thoughts on that one?

Which gear and is it when going down or up?
The adjustable screws or wire tension has got to be part of the answer.
If not low enough or high enough gear it is just the screws.

I'm not shifting when it happens--it just happens sporadically. In
terms of the gearing, it's a 10-speed and the chain is sitting on one
of the middle cogs in the cassette. When I ride on the road it
doesn't happen--shifts beautifully.


I would try loosening the screw for the wire tension down by the derailleur
since that is what you say is causing the tension. If that is not enough
lengthen the wire at the adjustment where the wire is fastened.