Strange noise when turning pedals on new bike

[MikeJD]

Hi all,

After recently indexing the gears on a new bike (not yet written), I’ve come back to it tonight to check everything over and there’s a noise I’ve not noticed before. Any ideas? Wondering if the chain needs lube or it’s the bottom bracket, obviously more worrying.

Video below, try ignore the usual chain sound.


Many thanks

 

[Spiderweb]

You look to be in a gear that is better not to use, you need to avoid these extremes (small sprocket front & back or large sprocket front & back).
Sounds like your chain is rubbing on the front mech.
Put your chain on the big ring and in the middle of the cassette and try again.

 

[BoldonLad]

Chain appears to be at maximum "opposites", not a situation normally regarded as wise. Is chain simply fouling the front mech "cage" ? ie, does noise go away as you move rear mech towards larger cogs?

Edit: oops! you beat me too it, @Spiderweb, my typing is too slow!

 

[fossyant]

Small small / large large don't use - cross chaining. The chain will be trying to shift up on the chain ring ramps etc.

 

[raleighnut]

Ditto to the above comments

 

[Cycleops]

It may be possible to adjust it out to an extent. Take it back to the shop and let them have a go at it for you but you are running the chain at a less than ideal angle, see below:

This causes friction and wear. Try to run it a straight as possible. In day to day riding you will hardly ever need to use those combinations.

 

[Yellow Saddle]

Show us a photo, side-on of the RD and cassette, with that gear engaged. It seems to me that the chain is too long and scraping against itself at the jockey cage. Maybe the chain isn't even threaded through the cage correctly. But let's see. That chain bouncing like that on the top run also worries me. It seems as if the chain is scraping against the inside of the larger chainring and hooking on the ramps.

 

[MikeJD]

I thought it could be cross chaining, as I’ve always known that’s not good practice. The reason I was indexing the gears was because how the bike came, at the extremities there was a lot of rubbing on the front mech. After spending hours trying to get it right it seems I may of messed something else up if the chain is rubbing on the ramps.

Here’s the chain straight in the largest rear cog and the small at the front (chain doesn’t contact front mech), still the noise faintly exists:




Let me know if you have any idea what I could of adjusted incorrectly to cause this.

Thanks

 

[Yellow Saddle]

I thought it could be cross chaining, as I’ve always known that’s not good practice. The reason I was indexing the gears was because how the bike came, at the extremities there was a lot of rubbing on the front mech. After spending hours trying to get it right it seems I may of messed something else up if the chain is rubbing on the ramps.

Here’s the chain straight in the largest rear cog and the small at the front (chain doesn’t contact front mech), still the noise faintly exists:




Let me know if you have any idea what I could of adjusted incorrectly to cause this.

Thanks

The two videos show different things. Show me a side-on view of the RD, with the chain in the position as per video 1, i.e. small chainring, small sprocket.

 

[MikeJD]

The two videos show different things. Show me a side-on view of the RD, with the chain in the position as per video 1, i.e. small chainring, small sprocket.

Sorry about that, just wanted to show the noise was still there in the low front, high rear combination that wasn’t cross chaining.

Here’s a video and some images in the low front, low rear combination where the sound is most noticeable.



In the experience you guys have had, is it ever possible to set the gears up to such a degree that there will be no chain rub at either extremity? It seems I can only achieve no rub on the FD at one end, and to correct the opposing extremity puts the one which was fine out.

Thanks

 

[berty bassett]

To me it sounds like the chain slightly touching front mech - also when it the smallest cog at back it may be just out a little so just tweaking screw at back after trying front mech - good luck

 

[MikeJD]

To me it sounds like the chain slightly touching front mech - also when it the smallest cog at back it may be just out a little so just tweaking screw at back after trying front mech - good luck

Unfortunately there's no contact on the front mech, do you mean tweaking the screw on the rear mech or the low limit on the FD?

 

[Yellow Saddle]

here the sound is most noticeable.

In the experience you guys have had, is it ever possible to set the gears up to such a degree that there will be no chain rub at either extremity? It seems I can only achieve no rub on the FD at one end, and to correct the opposing extremity puts the one which was fine out.

Thanks

No, it isn't possible. It is a function of the lateral distance the chain has to cover to cross over to a far-side sprocket and the length of the chainstays. You can't change either of these two factors.

Further, limit screws only limit the two final travel positions of each derailer. For example, if the indexing is perfect, you can actually remove the limit screws and it will have no effect on the gear changes. Also, adjusting a limit screw at one end changes nothing at the other end. They only work on the side they're intended to work on.

I still can't figure out enough from your video to decide what's wrong, if indeed there is anything wrong. I think without extensive video-ing with the help of an assistant and a steady camera, we can't help. It is up to you to physically look for contact between components.

Cross-chaining is an absolute no-no, it causes all sorts of noises and undesirable wear in the chain, sprockets and bottom jockey pulley. Just don't do it.

 

[Smokin Joe]

This would be unusual on a new bike, but check that the chain isn't riding on top of the tab between the jockey wheels on the rear mech. That makes a similar sort of noise and it isn't beyond possibility that it was fitted wrong on assembly.

 

[Milkfloat]

This would be unusual on a new bike, but check that the chain isn't riding on top of the tab between the jockey wheels on the rear mech. That makes a similar sort of noise and it isn't beyond possibility that it was fitted wrong on assembly.

That was my first thought, but after he changed gear the noise pretty much went away.