Vtyjkyuk

I recently got an old bicycle for the sole purpose of using it on a trainer. It has old non-indexed levers for gear changing and they don't seem to work OK. The front one slips into lower after a while, and the rear one is now "locked" since it's plastic, I don't want to force it and break it.

I don't want to invest much into this bike, it was already more than I was planning to spend on it.

I was thinking to remove them and fix the derailleurs on a specific gear ratio. I would like to be able to adjust the rear one, but wouldn't mind if the process is somewhat cumbersome (ie: requires tools).

Is this possible? What would be the best path to do it?

Some pictures for clarification:

Shifters:

Front derailleur:

Rear derailleur:

There doesn't seem to be any barrel adjuster on the derailleur side, just on the shifters.

The simplest method I can think of is to put the shifters into the position with the least cable tension (normally the small ring at the front as well as the rear) and then undo the cable from the derailleur. Next, move the derailleur into the gear you want and tighten the cable in this new position.

A bit more detail:

It might need two people. With the bike off the ground turn the pedals and push the rear derailleur into position and have it held there. Be careful with your fingers near the moving parts! Stop the wheel and tighten the cable. Finally use the barrel adjuster to index the gear.

Make sure the lower limit screw will prevent the chain ever going into the spokes, but it already should be doing that job.

The other tweak for the rear derailleur is to remove the inner cable and insert it directly into the derailleur and tighten it off in the gear you want. It would be very short and doesn't need to go through any housing. That would be locked in, but you could change the gear without shortening the chain, by adjusting the cable again. This would work better if the shifter proves not to be reliable for the above method.

If I understand correctly you have slipping shifting levers that let the derailleurs move without your intervening. A non-indexed shifter slips because the friction setting is too low.

Friction of the lever is easily adjusted by a screw at the side of the lever. If it still slips after tightening you'll unscrew the thing taking care to remember the correct order of items when is comes apart. (Take a photo maybe to assist your memory.) Then clean the bits to remove any grease and reassemble. It usually helps. At least it did in the old days before indexed gears.

The really quick and dirty method (after removing the shift levers) would be to use a vise-grip plier and pinch the cable at the required position while it's routed through a cable brazing on the frame. That enables relatively quick gear changes although the cable will get mangled over time. Another disadvantage is that you have a plier hanging from the bike and it might get in the way if you can't find a suitable spot.

Another quick method would be to tie a knot in the cable instead of using a plier but this makes it a little more difficult to accurately set the derailleur.

These solutions are the ones where cost is nil. Considering the bike won't even move as it's on a trainer, the plier method isn't that out of place.

Yes, it is possible. The actions needed would be:

• remove rear wheel (you need suitable wrench unless you have quick-release axle)


• remove chain (you need a chain breaker unless you can find a master link and disengage it)


• remove both front and rear derailleurs (most likely Phillips head screwdriver is the tool you need, perhaps suitable allen key or a wrench)


• remove derailleur cables and shifters (again, Phillips head screwdriver, allen key or a wrench, depending on how the shifters were mounted)


• put back the rear wheel


• put the chain back on the desired chainring (front) and sprocket (rear), measure how long it needs to be, using the chain breaker set the correct length and affix the chain


• tension the chain by readjusting the rear wheel

This way you have converted your bike into a semi-single speed the cheapest way possible. And you won't be carrying the weight of the parts you are not using.

If you want to go further in reducing weight you may replace the freewheel/cassette with a single-speed freewheel (you need freewheel remover tool) and unused front chainrings (you need crank remover and most likely chainring nut wrench).

Your rear derailleur has upper and lower limit screws (so does the front), which will usually be either on the "knuckle" at the back of the derailleur or on the outer side plate. These limit the derailleur's travel. Because the derailleur is sprung, you really only need to worry about the low-limit screw; the spring will hold it against the limit. Depending on what gear you want, you may not get enough range out of the limit screw, but that's where I'd start. All you'll need is a screwdriver.