Author Topic: Grumbling drive train  (Read 2873 times)

bloomers100

  • ACME's Head of Sexual Health and Family Planning
Grumbling drive train
« on: September 18, 2016, 12:43:12 pm »
I had a section of chain grumbling so I fitted a new chain (3/32), now when under force its grumbling all the way round, when nor being pushed its fine. Bottom bracket is new, wheel bearings fine. Everything seems to be in line and the chain isn't too tight. Surly rear sprocket kmc chain.

Any ideas? Carry on riding it to see if it all wears in a bit?

Re: Grumbling drive train
« Reply #1 on: September 18, 2016, 10:56:12 pm »
You might need to change the cog or the chain ring. You might even have to change both. It sounds like you have a worn transmission, how many miles has it done?

bloomers100

  • ACME's Head of Sexual Health and Family Planning
Re: Grumbling drive train
« Reply #2 on: September 19, 2016, 03:35:41 pm »
It's done a lot over about 6 years

Re: Grumbling drive train
« Reply #3 on: September 19, 2016, 06:31:11 pm »
Most likely the cog, and yes it should settle down. If it's no better after 200 km or so, change the cog.
Quote from: tiermat
that's not science, it's semantics.

Re: Grumbling drive train
« Reply #4 on: September 19, 2016, 06:34:34 pm »
It's done a lot over about 6 years

Sounds like its about time for renewing the transmission, after 6 years it don't owe you anything..

fd3

Re: Grumbling drive train
« Reply #5 on: September 19, 2016, 08:38:34 pm »
I can damage my transmission in under a year.
(Through being inept...)

Jonah

  • Audax Club Hackney
Re: Grumbling drive train
« Reply #6 on: September 19, 2016, 09:11:25 pm »
Hold the cog (and chain-ring) up to the light - if the teeth arch over to one side it's knackered.


Re: Grumbling drive train
« Reply #7 on: September 21, 2016, 07:08:27 am »
I realise that I am going to invoke some sort of God of the Fixies but slacken the chain just a bit and see if it continues. 

Oaky

  • ACME Fire Safety Officer
  • Audax Club Mid-Essex
    • MEMWNS Map
Re: Grumbling drive train
« Reply #8 on: September 21, 2016, 08:07:14 am »
This thread reminds me of the time I posted a picture of my cog here with the question "Is my cog worn out?" to receive the reply (from ChrisS, IIRC):  "Oaky,  that's barely worn in!" ;)
You are in a maze of twisty flat droves, all alike.

85.4 miles from Marsh Gibbon

Audax Club Mid-Essex Fire Safety Officer
http://acme.bike

Re: Grumbling drive train
« Reply #9 on: September 22, 2016, 10:15:47 pm »
Are the chains both the same type?  A full-bushing chain can crackle with a tiny misalignment in chainline, where a bushingless chain will run quietly.  It's probably a worn cog but I've fallen into the trap if fitting a supposedly superior "track chain" only to discover that the 2mm by which my chainline was out was too much for it.  My chainline is perfect now, obviously  O:-)
Never tell me the odds.

Re: Grumbling drive train
« Reply #10 on: September 22, 2016, 10:16:35 pm »
This thread reminds me of the time I posted a picture of my cog here with the question "Is my cog worn out?" to receive the reply (from ChrisS, IIRC):  "Oaky,  that's barely worn in!" ;)

 :thumbsup:

Re: Grumbling drive train
« Reply #11 on: September 22, 2016, 10:27:53 pm »
It's a while since I had the courage to ride fixed (Good Friday, 2014 - look it up, if you CBA - or care less).

My fixed bikes (A Pomp, and an 80s Dawes conversion) were mostly silent and non-grumbly. I have no pretence at fettling skills, but what I found kept grumbliness to a minimum was:

a. 1/8th throughout. Just do it.
b. Work on getting a decent chainline.
c. Keep your chain taught. If you can't play it with a bow - it's not tight enough. Anything that looks like a washing line - well...
d. Use a gear that sits right between your sweetspot - which is a pseudo-mythical point between the cadence you can handle spinning downhill, and the "Almost a trackstand" point you can handle uphill.  :thumbsup:

bloomers100

  • ACME's Head of Sexual Health and Family Planning
Re: Grumbling drive train
« Reply #12 on: September 23, 2016, 06:27:21 am »
I will have a fiddle this weekend.......then I'll try and sort my bike out.

Thanks for the replies.

Re: Grumbling drive train
« Reply #13 on: September 23, 2016, 08:29:59 am »
c. Keep your chain taught. If you can't play it with a bow - it's not tight enough. Anything that looks like a washing line - well...

Isn't that a good way of killing wheel (and possibly BB)  bearings in short order? The chain needs to be reasonably taut, but still have a little bit of deflection - I've always gone for a cm or two of vertical movement, at least when I'm paying attention to it.

LittleWheelsandBig

  • Whimsy Rider
Re: Grumbling drive train
« Reply #14 on: September 23, 2016, 08:37:33 am »
Yes. Trackies often have the chain slightly looser than even that, to minimise chain friction.
Wheel meet again, don't know where, don't know when...

Re: Grumbling drive train
« Reply #15 on: September 23, 2016, 08:56:48 am »
c. Keep your chain taught. If you can't play it with a bow - it's not tight enough. Anything that looks like a washing line - well...

Isn't that a good way of killing wheel (and possibly BB)  bearings in short order? The chain needs to be reasonably taut, but still have a little bit of deflection - I've always gone for a cm or two of vertical movement, at least when I'm paying attention to it.

Well, clearly - not so tight that it binds, duh!  :D

I'd rather spend a few £s on a BB or new sprocket, than have my chain ship when hurtling downhill (which is when it's most likely to happen - when the slack is at the top, not the bottom).

Re: Grumbling drive train
« Reply #16 on: September 23, 2016, 09:15:11 am »
c. Keep your chain taught. If you can't play it with a bow - it's not tight enough. Anything that looks like a washing line - well...

Isn't that a good way of killing wheel (and possibly BB)  bearings in short order? The chain needs to be reasonably taut, but still have a little bit of deflection - I've always gone for a cm or two of vertical movement, at least when I'm paying attention to it.

Well, clearly - not so tight that it binds, duh!  :D

I'd rather spend a few £s on a BB or new sprocket, than have my chain ship when hurtling downhill (which is when it's most likely to happen - when the slack is at the top, not the bottom).
Big sprockets ftw

slack chains cost teeth

According to an old book I had, the test is to put your bike on a stand, turn the pedals, and try to push the chain off sideways with the handle of a spanner. It shouldn't be possible.
<i>Marmite slave</i>

Re: Grumbling drive train
« Reply #17 on: October 07, 2016, 09:49:47 pm »
Optimum: as tight as possible with no visible droop, and evely tight throughout the rotation with no binding.  You can improve the apparent roundness of the shainring by loosening the spider bolts a bit and gently tapping the chainring towards the sprocket at tight spots in the rotation.  There is a real skill to this which I've never perfected, but it can make a worthwhile difference to the amount of up-and-down chain movement.

Crappy component compromise: if you can't actually push the chain off the chainring or sprocket anywhere in its rotation (watch your fingers!) it's fine.
Never tell me the odds.

bloomers100

  • ACME's Head of Sexual Health and Family Planning
Re: Grumbling drive train
« Reply #18 on: November 23, 2016, 07:01:46 pm »
Whole new drivetrain.

It was the cog  ::-)