consequences of shifting gear with motionless chain

[DynV]

*sigh* /img/vbsmilies/smilies/frown.gif

I just bought a quasi-new folding bike less than half-priced. The seller tell me she didn't even went further than 20' with it ; and whether she's exaggerating, it certainly looked like it. It has a single derailleur, at the rear, and a twist-style indexed shifter. While I was doing the final inspection, she (seller) changed gear while the chain wasn't moving ahead, not moving at all in fact. Now the chain won't reach the lowest gear and at the highest gears, the chain has a tendency to go higher.

I assume this stretched something: cable, derailleur spring, shifter, or something else entirely? Would regular repair guide help me with such abnormal behavior? If not, what kind of tutorial or howto should I be looking for?

Why didn't I stop the seller from doing this? Was I afraid to offend her and she'd retract the sale?

Thanks

 

[AndrewGronow]

The shifting was probably out to begin with. Sounds like the upper and lower limits of the derailleur need adjusting.The previous owner had no idea how to fix it and just rode it as is. Shouldn't be any harm done. This is very easy to do. Take a look at this Video for adjustment.

 

[Pat Stowe]

it is possible to harm components when shifting gear with motionless chain

 

[AndrewGronow]

Originally Posted by Pat Stowe .

it is possible to harm components when shifting gear with motionless chain

Please elaborate

 

[dabac]

Originally Posted by AndrewGronow .

Please elaborate

Originally Posted by Pat Stowe .

it is possible to harm components when shifting gear with motionless chain

When you shift on an externally geared bike, the chain is supposed to move sideways. But to be able to do that, it has to disengage with one set of teeth and mesh with another set, on the next sprocket/chainring. And to be able to do that, the chain has to be moving.
Trying to shift with a stationary chain will force the derailer against a chain that isn't disengagin, so if you insist, you run the risk of causing the cable to slip, derailer to bend, or something to break.

 

[danfoz]

The derailleur was likely not adjusted properly to begin with. Not shifting into the biggest and smallest gears is a dead give away that the "limit screws" may have needed adjusting. Real damage occuring is highly unlikely. The cable might slip which is unlikely if it was properly tightened. Doubtful anything bent. Take it to a bike shop and get yourself properly adjusted. Should be about 10-20 bucks depending on where you live.You're letting folks get you worried.

I'd hazard a guess that almost everybody at some point in there lives when changing a wheel out has put the chain back on to a rear cog that it didn't start on, thus esentially shifting at least one gear "motionless". i.e creating the same forces on the RD. If she cranked it all the way? That's possibly another story.

 

[danfoz]

Originally Posted by AndrewGronow .

The shifting was probably out to begin with. Sounds like the upper and lower limits of the derailleur need adjusting.The previous owner had no idea how to fix it and just rode it as is. Shouldn't be any harm done. This is very easy to do. Take a look at this Video for adjustment.

This.

 

[alienator]

The derailleur was likely not adjusted properly to begin with. Not shifting into the biggest and smallest gears is a dead give away that the "limit screws" may have needed adjusting. Real damage occuring is highly unlikely. The cable might slip which is unlikely if it was properly tightened. Doubtful anything bent. Take it to a bike shop and get yourself properly adjusted. Should be about 10-20 bucks depending on where you live.You're letting folks get you worried. I'd hazard a guess that almost everybody at some point in there lives when changing a wheel out has put the chain back on to a rear cog that it didn't start on, thus esentially shifting at least one gear "motionless". i.e creating the same forces on the RD. If she cranked it all the way? That's possibly another story.

Yup.

 

[daveryanwyoming]

All good advice above and it's highly unlikely that a 'dry shift' caused any problems. Definitely get it into a shop for a check out and tune up but two other things they should check:

- Make sure they check derailleur hanger alignment as these can easily get tweaked if the bike is laid down on the drive side and can cause exactly what you're describing. Simple limit screw adjustments may or may not resolve this issue depending on how the hanger was bent. Some shops are a bit lazy with this and just eyeball the derailleur alignment as it takes a few more minutes to use the shop tool. But those extra couple of minutes are worth it as the tool tells you if the hanger is straight and parallel in multiple axes and if it's twisted which is a very difficult thing to eyeball. If you get the derailleur adjusted and it reaches all gears but the shifting is still funky and unpredictable in some gears but not others then definitely check hanger alignment.

- Make sure they check for appropriate spacer(s) (or not) between the hub and the cassette. If the drive train was adjusted with a spacer in place (typically a 1mm shim but thicker for some brand hubs like some Mavic hubs) and then the cassette was removed for cleaning or changed to a different gearing and reinstalled without the spacer you'll also get the symptoms you describe of not being able to get into the small tooth cog and overshifting the large cog and up and over into the spokes or spoke protector. This can usually be resolved with limit screw adjustments but if the spacer(s) should be in place for a particular hub/cassette combo then it's better to have it in place to maintain sufficient derailleur cage to spoke clearance which can be an issue with some wheel builds.

-Dave

 

[oldbobcat]

The "dry shift" itself shouldn't cause problems, but turning the chain right afterward can, if it's to a larger chainring in front. I've seen bent chains, bent derailleurs, bent chainrings, and bent crank spiders caused by manky chainring shifts.

If you think you inadvertently dry-shifted, check chain alignment before stomping on the cranks. Lift rear wheel, turn crank gently by hand, and shift back down.

 

[stevenjoywell]

yeah, i think so,The "dry shift" itself shouldn't cause problems, but turning the chain right afterward can, if it's to a larger chainring in front. I've seen bent chains, bent derailleurs, bent chainrings,

 

[DynV]

Originally Posted by oldbobcat .

The "dry shift" itself shouldn't cause problems, but turning the chain right afterward can, if it's to a larger chainring in front. I've seen bent chains, bent derailleurs, bent chainrings, and bent crank spiders caused by manky chainring shifts.

If you think you inadvertently dry-shifted, check chain alignment before stomping on the cranks. Lift rear wheel, turn crank gently by hand, and shift back down.

Sorry for the very late reply ; I guess I missed a notification and most forums won't re-notify before the thread is checked again.

What do you mean turning the chain right afterward? I should give it some seconds to cool-down? Or there should be a procedure before turning the crank (by using pedals) ? If it's the latter, it should amount to

Originally Posted by danfoz .

[...] I'd hazard a guess that almost everybody at some point in there lives when changing a wheel out has put the chain back on to a rear cog that it didn't start on, thus esentially shifting at least one gear "motionless". [...]

 

[alienator]

By "turning", he means rotating the cranks.