Chain scraping on rear sprockets

Adjusted my gears yesterday, and am reading www.sheldonbrown.com, however I wonder if anyone can
help here?

The problem is on the higher gears, and when I 'give it a bit' it makes a scraping noise under
pressure. Middle ring to biggest ring is all fine. Is this just a simple twist of the H screw on the
derailleur? I guess if I understand wht i've done wrong, I'll know for next time.

</embaressed to ask moment over>

Thanks

Nick

 

elyob wrote:
> The problem is on the higher gears, and when I 'give it a bit' it makes a scraping noise under
> pressure.

On the big ring only? If so, and the noise sounds like the chain scraping the front derailleur, then
you probably need to twiddle the H screw (and possibly cable) more to allow room for crankset and
frame flex when you apply the welly. Altering the angle of the front derailleur may also help.

> Middle ring to biggest ring is all fine.

Sorry, I'm not clear what you mean. No problems at all when using middle and outer chainrings?

If problem is only occurring on the little ring - you shouldn't be using the small ring-small rear
sprockets combinations at all (chain will be too crossed over).

~PB

 

"Pete Biggs" <pLime{remove_fruit}@biggs.tc> wrote in message
news:[email protected]...
> elyob wrote:
> > The problem is on the higher gears, and when I 'give it a bit' it makes a scraping noise under
> > pressure.
>
> On the big ring only? If so, and the noise sounds like the chain scraping the front derailleur,
> then you probably need to twiddle the H screw (and possibly cable) more to allow room for crankset
> and frame flex when you apply the welly. Altering the angle of the front derailleur may also help.
>
> > Middle ring to biggest ring is all fine.
>
> Sorry, I'm not clear what you mean. No problems at all when using middle and outer chainrings?
>
> If problem is only occurring on the little ring - you shouldn't be using the small ring-small rear
> sprockets combinations at all (chain will be too crossed over).
>
> ~PB

Sorry, I'm always a bit vauge ... I really felt like saying 'the thingie on the whodjamiflip'

It's on the small rings (outer chainring?) that the noise happens ... It happens on the bottom
three, though I don't use the smallest one or two due to crossing the chain as you mentioned. That
was a good point r.e. flex .. i'm a big lad ... I'll have a play with it tonight and see what
happens. The H is for the small rings, right?

Thanks

Nick

 

elyob <[email protected]> wrote in message
news:yW%[email protected]...
>
> "Pete Biggs" <pLime{remove_fruit}@biggs.tc> wrote in message
> news:[email protected]...
> > elyob wrote:
> > > The problem is on the higher gears, and when I 'give it a bit' it makes a scraping noise under
> > > pressure.
> >
> > On the big ring only? If so, and the noise sounds like the chain scraping the front derailleur,
> > then you probably need to twiddle the H screw (and possibly cable) more to allow room for
> > crankset and frame
flex
> > when you apply the welly. Altering the angle of the front derailleur
may
> > also help.
> >
> > > Middle ring to biggest ring is all fine.
> >
> > Sorry, I'm not clear what you mean. No problems at all when using
middle
> > and outer chainrings?
> >
> > If problem is only occurring on the little ring - you shouldn't be using the small ring-small
> > rear sprockets combinations at all (chain will be
too
> > crossed over).
> >
> > ~PB
>
> Sorry, I'm always a bit vauge ... I really felt like saying 'the thingie
on
> the whodjamiflip'
>
> It's on the small rings (outer chainring?) that the noise happens ... It happens on the bottom
> three, though I don't use the smallest one or two
due
> to crossing the chain as you mentioned. That was a good point r.e. flex .. i'm a big lad ... I'll
> have a play with it tonight and see what happens. The H is for the small rings, right?
>
> Thanks
>
> Nick
>
>
>

Check the angle of dangle screw. The chain may be touching on the underneath of the derailleur. I
put up with a noise for weeks before I realised what it was!

--
Mark
____________________________
Practice does not make perfect... Perfect practice makes perfect

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elyob wrote:
> It's on the small rings (outer chainring?) that the noise happens ... It happens on the bottom
> three, though I don't use the smallest one or two due to crossing the chain as you mentioned. That
> was a good point r.e. flex .. i'm a big lad ... I'll have a play with it tonight and see what
> happens.

I'm sorry mate, I can't figure out what's going on there. It's one of those situations where I would
need to get my eyeballs, lug holes, mitts and backside on the bike.

> The H is for the small rings, right?

It stops the derailleur shifting the chain off the outside of the largest chainring.

"Chainrings" or "rings" = front sprockets on the cranks

As an alternative to SB's instructions, try:
http://www.parktool.com/repair_help/FAQindex.shtml#drivetrain

~PB