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View Full Version : Mounting a Shimano triple front derailer??



MrIdaho
12-18-2014, 08:58 PM
looks like I need to renvent the wheel on how to mount the Shimano triple derailers to my BB.
here are the pics of what I have so far unless someone has a better idea. Tried locating a pic of an actual unit on a bike but ??
I have the unit mounted on the end of a 1/2" od tube. It is pretty solid but where to go from here?? to get it mounted at a 57degree angle to the BB
http://i992.photobucket.com/albums/af44/MrDEB/derailer003_zpsadd17a07.jpg (http://s992.photobucket.com/user/MrDEB/media/derailer003_zpsadd17a07.jpg.html)
http://i992.photobucket.com/albums/af44/MrDEB/derailer002_zps990c6061.jpg (http://s992.photobucket.com/user/MrDEB/media/derailer002_zps990c6061.jpg.html)

http://i992.photobucket.com/albums/af44/MrDEB/derailer001_zps071f5337.jpg (http://s992.photobucket.com/user/MrDEB/media/derailer001_zps071f5337.jpg.html)

Ticktock
12-19-2014, 04:18 AM
THe pics are a bit too blurry to really help.
But --here goes with the things to watch for.
One--forget any angle in degrees! the derailer must allow the chain to pass freely through in all the gear positions.
This will result in the derialer being mojunted in exactly the same position relative to the CHAIN as it was on the original bike!. The angle reffered to in the AZ plans is given because Brad has a pretty good idea where it has to be for that bike--not your bike! Its the top chain line that dictates where the derailer has gto go.
Next, it must just miss the big cog--too low means noises and no gear change--too high means different noises amd still no gear change.
Then it must be able reach over the complete width of the three chain rings. Most derailers have more movement than you actually need, but not much more, so it has to be close . Again, copy the original bike.
Actually , best advice is to copy the original bike , but remember that its all relative to the drive side of the chain. Look at a Front wheel drive as a good example--its exactly the same layout, just turned upside down. And best way to mount it is on a piece of bike down tube!
Steve G

Twinkle
12-19-2014, 06:08 AM
Mr I

Have to agree with Steve here , Forget the angle and go for the position where the guide runs "nicest fit " to the chainwheel , chain even the idle pulley position or the size of the chain wheels and the optimum position change , it time to sit and look at the problem and using a piece of string as a chain line find the best position for the chain drive system that you are designing . I have used some of the cheapo shimano front mechs with built in cable guide and they can actually run quad 46-22 t thun chainset happily if fitted at the correct angle .

regards emma

MrIdaho
12-19-2014, 10:56 AM
Be nice if I had the original but I purchased just the derailers themselves.
Have several ideas to mount but the thing that worries me is the amount of force to move the mechanism but I realize I am only using the short arm to move so leverage is against me.
Going to ponder solution but need to get my lighting back to working. The two halogen work lights are brand new but only have about 20 hours on them and the bulbs burned out.
Just can't win!!

Twinkle
12-19-2014, 01:47 PM
The two halogen work lights are brand new but only have about 20 hours on them and the bulbs burned out.
Just can't win!!

If these are the 500w ones with the long bulbs (80mm ish ) try replacing the bulbs with 300w ones, the big ones /( 500w ) run so hot they fail very quickly , my 300w ones last a lot longer and are cheaper to run and I don't need sunglasses any more .!!!!!

regards emma

MrIdaho
12-19-2014, 05:43 PM
THANKS will look into using the smaller 300w bulbs. In the mean time I have two florescent lamp bulbs for light. They are better than nothing.
I managed to get the BB and derailer mess straighten out. Will post pics tomorrow. The weather turned cold so into the house we go.

Doc.
12-21-2014, 03:16 AM
If you really want to 'reinvent the wheel'/'think outside the box' , and depending on your skill-set, maybe you could try something like this instead . . .
http://img.photobucket.com/albums/v93/docv400/designboom-derailleur-01-bl_zps404c2981.jpeg (http://smg.photobucket.com/user/docv400/media/designboom-derailleur-01-bl_zps404c2981.jpeg.html)
http://img.photobucket.com/albums/v93/docv400/designboom-derailleur-02-bl_zpse6c70209.jpg (http://smg.photobucket.com/user/docv400/media/designboom-derailleur-02-bl_zpse6c70209.jpg.html)

MrIdaho
12-21-2014, 10:02 AM
WOW Doc that is one sweet piece of engineering.
Did you build or ??