method of adjusting shimano rear derailer

[craisin]

Does anybody know the proceedure of adjusting the shimano rear derailer.
So I bought a motor and I couldnt easily fit it to my frame so a friend had heaps of old racing style bike and he let me take 3 of them.
2 of them were 12 speeds and the one I used had the cogs missing off the derailer
In the end I put a more modern derailer and a twist grip 6 speed shifter off a smaller bike it works quite well but not consistantly well
thanks in advance

 

[Pablo]

http://bicycletutor.com/adjust-rear-derailleur/

http://forums.bicycletutor.com/forum-25.html

 

[craisin]

Thanks Pablo I can only only find 2 adjustment screws the B and the H.
I think that other screw is in a different location
I do have another parts bike that has that type of angled derailer but it would mean modifying the frame to mount that type derailer.
Anyway its given me the basic understanding of it.

 

[craisin]

update,
I have to admit I followed your link to the forum and I just had to read the first answer to the clues so I counted the teeth on low gear and 28 total same as the wheel on the donor bike eg the bike I got the derailer and shifter off.
My bike may be a part bin special from the early 70s it looks as it was painted in Commonwealth Games colours.
I need to lose the steel Rims
I have to keep an eye out for a wheel off a racebike with less than 28 on the big cog
sweet

 

[retromike3]

rear derailleur

There are usually more than two adjustments for a modern derailleur. First there are the ends for the top and bottom adjustment then there is a separate adjustment for cable tension. This is a ferrule usually at the shifter that helps you adjust weather the amount of upshift or down.

If you go to a bike shop you can get a bolt on derailleur hanger from a less expensive bike that clamps to the place were the wheel bolts to the frame. this peace of steel will let you install a newer derailleur to an older frame.

On the back of most derailleurs they have a set of numbers that say how many teeth they can handle very few can handle less than 28. There are usually three sizes of derailleurs, short ,mid and long. I had a mountain bike racer in my old bike shop that used a short cage derailleur for a 28 tooth cog set. what he did was shorten the chain until it pulled the rear upper pulley clear of the freewheel. This worked but you could not use the big chainring with the big cog in the back or it would jam.

thanks -Mike Frye- the bike guy

 

[Nuttsy]

Also, make sure you're not using apples and oranges. On cheaper department store type bikes that utilize index shifting, if you have a Shimano shifter and say a Falcon freewheel set, you will probably get inconsistant shifting. It has to do with cog spacing and deraileur travel.

 

[craisin]

good points mike and nuttsy
Yes Mike its come to my attention that adaptor claw you speak of
I have got rid of the front derailer and fitted the freewheel that goes with a jackshaft,and the original front big chainring was bigger the present one

I plan to ride the bike without fitting the engine for a while to make sure things work together

I want to upgrade to canterlever brakes before I put the engine on

 

[retromike3]

cantilever brakes ?

The next question is :is your bike already set up for cantilevers? Most bikes that have cantilevers are already set up with what's called a "derailleur hanger". If your not, then you will need to install cantilever studs. They are two brazed on cylinders per brake that the cantilevers rotate on and without them cantilevers are not feasible.

I was thinking of making a plate that had cantilever studs built into it that you could mount on a standard front fork for a friend who has a racing wheel chair. He has problems with putting enough presser on his brake levers and I thought cantilevers with magura hydraulic brakes would stop his in no time.

Mike Frye-the bike guy

 

[craisin]

true mike
I cut the cantilevers off a Bike called a Viva S but it had no derailer hanger like you suggest.
I come from New Zealand.
Anyway I cut off about 3inches of tube that have the cantilevers mounts then I split the tube in half and I intend to get a friend to mig weld the half tube and mount over the slightly smaller tube on the older bike [thats on the back]

I tossing up weather to put shocks on the front depends if I can modify them to suit

 

[Mountainman]

if you have a bike stand
get that thing on the stand and work through those gears
someone else can pedal with their hand so as to give you the whole picture
you will easily see which screw stops are for low and high gear
as you play with those things
adjusting them up and down ((a little)) until you see exactly the change

as mentioned above mix matching shifting levers to derailers may not be compatible

MM - The Old Bike Shop Owner --