View Full Version : Chain or de-railer noise?

07-16-2013, 10:38 AM
I have a similar thread under ? but which thread??
Well I changed the front cranksprocket from a 40/50 to a 28/38/48 crank sprockets.
Changed out the de-railer from a Shimo 515 to a Shimo RS-improved shifting but still noise
I changed the angle on the de-Railer mount from horizontal to vertical (referring to axle slot)but didn't make any difference.
Looking at pics the chains don't run parallel? Could be issue but why, I need to investigate.
Tried taking pic w/ chain on center sprockets but battery died in camera.
http://i992.photobucket.com/albums/af44/MrDEB/bike139_zps59e99f04.jpg (http://s992.photobucket.com/user/MrDEB/media/bike139_zps59e99f04.jpg.html) http://i992.photobucket.com/albums/af44/MrDEB/bike138_zpsc27419e4.jpg (http://s992.photobucket.com/user/MrDEB/media/bike138_zpsc27419e4.jpg.html) http://i992.photobucket.com/albums/af44/MrDEB/bike137_zpsf24e4781.jpg (http://s992.photobucket.com/user/MrDEB/media/bike137_zpsf24e4781.jpg.html) http://i992.photobucket.com/albums/af44/MrDEB/bike136_zps22d78e8d.jpg (http://s992.photobucket.com/user/MrDEB/media/bike136_zps22d78e8d.jpg.html) http://i992.photobucket.com/albums/af44/MrDEB/bike135_zpsf072a7c3.jpg (http://s992.photobucket.com/user/MrDEB/media/bike135_zpsf072a7c3.jpg.html) http://i992.photobucket.com/albums/af44/MrDEB/bike134_zpsf1ede691.jpg (http://s992.photobucket.com/user/MrDEB/media/bike134_zpsf1ede691.jpg.html)

07-16-2013, 10:41 AM
here is the other thread

07-16-2013, 11:36 AM
It is hard to see from the pics, but here are a couple of things:

1) It looks like you are using a hub as an idler, and I don't see any sort of chain guide which leads me to wonder if the chain can move freely across the entire hub surface?

2) If you look at a regular bike, you will notice that the bottom bracket is not centered in the frame. This is to account for the extra space that the chainrings take up on the drive side in order to maintain a bio-mechanically natural position, and it looks like yours may be centered which will disrupt your chainline when you have center chainring front and center cog back.

3) Any attempts to align your chain should always be done center to center, meaning center front chainring and center reag cog (or one of the two if you have an even number of rear cogs).

4) Perspective in picture is problematic, so you need to check all your parts in the drive chain end to end, and make sure that they are all 90 degrees. It looks like you have some that are positive and some that are negative which will also affect the alignment of your chain.

Radical Brad
07-16-2013, 12:52 PM
That idler must go!!!!
You will be flattening your chain, added MASSIVE friction, and I would bet when you pedal it sounds like a chiansaw.

A ball bearing idler puller with a diameter of no less than 4 inches will solve a lot of problems here.


07-16-2013, 03:01 PM
I thought a flat ideler would be better?
And yes it sounds kinda like a chainsaw when pedaling.
Will make some changes.
I was thinking that a pulley would cause the chain to flex side ways when changing gears.

Radical Brad
07-16-2013, 04:24 PM
The smaller the diameter of the idler, the more friction. A nylon v-belt pulley of 4-6 inches in diameter is perfect. A metal v-belt pulley is also good as the chain rides on the flat. In your situation, the chain is cutting into the axle tube.
I wouldn't;t doubt that with this setup, you are robbing 25% or more of your pedaling efforts.


07-16-2013, 06:20 PM
Even though the idler/hub rotates freely? 25% loss
Will change out tomorrow
On the alignment, the rear wheel is dead center in relation to the frame so moving the wheel more to one side?? might not be doable without cutting the dropouts off and re-welding.
Hopefully changing out the idler will do the deed.

Radical Brad
07-16-2013, 07:07 PM
Yep, huge losses, huge noise, metal-on-metal, chain wear.
Changing it will fix a lot of issues.


07-16-2013, 10:15 PM
You missed the point! The center cog at the back and the center cog at the front should be pointing straight at each other, and the line between them parallel to the center line of the wheel.
1/4 inch error is not going to be a disaster over that length of chain. The wheel hub idler is too small, and I would say, not quite true , as it seems to be the cause of the chain dragging off to the right all the time. If it was true, the chain would keep in a straight line, and wear over the whole face, not just one spot. That hub will wear thru quite quickly, by the way.
I have a cast iron roller on my LWB, and it has worn its own little tooth pattern into it over the last year. probably 2mm deep.
Steve G
Just aq stupid thought, but make sure that the chain is threaded through the derailer correctly--not touching any metal except the two small wheels. Back pedal slowly by hand and the only noise you should hear is the freewheel clicking

07-16-2013, 11:20 PM
...in terms of efficiency, my understanding is that chains are designed to run on their rollers, rather than on the links. This may not be such an issue on the slack (non-drive) part of the chain, which may explain why so many use tooled-out delrin, chopping board plastic, skate wheels etc to fashion an idler. A while back I saw some more exotic idlers on the web - very expensive - they were a sort of oversized jockey wheel sandwiched in some kind of plastic, and a proper bearing in the centre. These obviously allow for the chain to run on it's rollers with the least amount of drag. Anyhow, all a moot point to me really, my trike has a straight chain run with no idlers or derailleurs - nice and simple....

07-17-2013, 12:17 AM
Just to be clear on the potential alignment issues, I was referring to every chain contact point along the drivetrain, not the rear wheel, although that would be part of the drivetrain.

From the pictures it looks like you might have a couple of components sorted of twisted in relation to each other meaning that 1 or more components may not be "square" with the frame.


Radical Brad
07-17-2013, 10:00 AM
Another issue with the hub shell idler (which you are getting rid of) is the axle. It will definitely be flexing if you are in a low gear, and would probably bend with any real pedaling forces applied.


07-18-2013, 01:38 PM
I might have found why the de-railer LOOKS like the chain is not in a straight line. I had changed out the de-raier from a Shimo 515 to a shimo RS BUT failed to grinding off the little indexing tab on the back.
I also rotated the de-railer 90 degrees CCW, installed a 4" plastic lawnmower pulley (a wide flat pulley)
Going to test tonight as it is awful warm (read HOT outside) but ran it through the gears while adjusting and lots less noise. Looks like a straighter chain line.

07-18-2013, 08:12 PM
That little bump of metal would definitely cause a problem with the chain run! Well done for working it out . Wake up call for all of us--think we have all had that problem, so next time I will add to my list of possibles!
Hope it works now.
Steve G

07-18-2013, 09:59 PM
THANKS to all the input, I would NEVER thought the idler pulley being so small would cause such power loss.
I just got back from a test ride with plastic 4" pulley that is a flat not V pulley. Started out thinking I had the bike in LOW but it was in 6 gear out of 15 (middle sprocket on crank and largest on rear)
No noise and I felt I was in LOW but was not. BIG DIFFERENCE.
Also grinding off the little nub on the de-railer helped as well.
now to disamble and clean up the frame for primer and paint. I recall using apple cider vinegar to remove rust? and etch the metal for paint??