SRAM chains.

Nick said:

I have recently put a new chain on my road bike, the SRAM PC48.

Now it is almost impossible to change onto the biggest chain ring
using a SORA front dérailleur.

Regardless of what rear sprocket it's on? (I'm wondering if the new chain
is shorter than the old one).

Quoted message said:

This appears to be because the SRAM chain flexes from side to side
more than the original chain.

I can understand your logic but I think you're mistaken in believing that a
stiffer chain shifts better. I think actually it's the other way round and
is why chains are as flexible as they are.

Quoted message said:

I can play with the front dérailleur to
get shifting back but I suspect it will always be harder shifting
than it was with the original stiffer chain.

If I bought a more expensive chain (SRAM or otherwise) would it be
stiffer and hence have better front shifting properties.

No it would not be stiffer. Both cheap and pricey SRAM chains shift fine,
IME.

Quoted message said:

Also can I use the SRAM powerlinks on other chains

Yes as long as the "speed" is the same.

~PB

I scribbled:
......

Quoted message said:

I think you're mistaken in believing
that a stiffer chain shifts better.

I'm not so sure now:

from www.sheldonbrown.com/rinard/chain_stiffness.htm :
"Lateral flexibility of the chain may be a benefit to modern multi-speed
bikes, but a certain amount of lateral stiffness is sometimes needed on
older derailleur bikes whose jockey pulleys are farther from the cogs. These
bikes seem to shift better with a little lateral stiffness in the chain. The
greater the distance between the jockey pulley and the cogs, the less
precisely the derailleur controls the chain's placement onto the desired
cog. In this case excess lateral flexibility in the chain makes shifting
even less precise.

"I'm not sure if a laterally stiff chain affects front shifting, though
I would believe it if Shimano claimed a certain amount of lateral
flexibility helped SG-X shifting. In this design the chain engages two chain
rings at once over a fairly short circumferential distance, where the chain
must bend quite a bit. Maybe a highly flexible chain helps here."
- Damon Rinard

~PB

Pete Biggs said:

Nick said:

I have recently put a new chain on my road bike, the SRAM PC48.

Now it is almost impossible to change onto the biggest chain ring
using a SORA front dérailleur.

Regardless of what rear sprocket it's on? (I'm wondering if the new chain
is shorter than the old one).

Yes regardless of sprocket. Bit its always easier to shift up when on
the little sprockets, isn't it?

The chains are the same length.

Quoted message said:

Quoted message said:

This appears to be because the SRAM chain flexes from side to side
more than the original chain.

I can understand your logic but I think you're mistaken in believing that a
stiffer chain shifts better. I think actually it's the other way round and
is why chains are as flexible as they are.

It is just a suspicion. I haven't really had a serious go at adjusting
it for the new chain. Mainly I'm suspicious because I had the same
problem on my old bike, although in the end (on my old bike) I did get
it to shift it wasn't as good as my new bike shifted with its original
chain.

Quoted message said:

Quoted message said:

I can play with the front dérailleur to
get shifting back but I suspect it will always be harder shifting
than it was with the original stiffer chain.

If I bought a more expensive chain (SRAM or otherwise) would it be
stiffer and hence have better front shifting properties.

No it would not be stiffer. Both cheap and pricey SRAM chains shift fine,
IME.

Well if they are the same there is no point in paying more ;o) The very
good price of the PC48 is why I would like to get them to work.

If I had to pay a lot for new chains I might have to start oiling and
cleaning them :o(.

Quoted message said:

Quoted message said:

Also can I use the SRAM powerlinks on other chains

Yes as long as the "speed" is the same.

~PB

Pete Biggs said:

I scribbled:
.....

Quoted message said:

I think you're mistaken in believing
that a stiffer chain shifts better.

I'm not so sure now:

from www.sheldonbrown.com/rinard/chain_stiffness.htm :
"Lateral flexibility of the chain may be a benefit to modern multi-speed
bikes, but a certain amount of lateral stiffness is sometimes needed on
older derailleur bikes whose jockey pulleys are farther from the cogs. These
bikes seem to shift better with a little lateral stiffness in the chain. The
greater the distance between the jockey pulley and the cogs, the less
precisely the derailleur controls the chain's placement onto the desired
cog. In this case excess lateral flexibility in the chain makes shifting
even less precise.

I've not had a problem at the back.

Quoted message said:

"I'm not sure if a laterally stiff chain affects front shifting, though
I would believe it if Shimano claimed a certain amount of lateral
flexibility helped SG-X shifting. In this design the chain engages two chain
rings at once over a fairly short circumferential distance, where the chain
must bend quite a bit. Maybe a highly flexible chain helps here."
- Damon Rinard

That seems to be the opposite of what I'm observing. Although the SRAM
chain seems to be more forgiving of bad front back combinations, eg
small-small, big big.

Quoted message said:

~PB

in message <[email hidden]>, Nick ([email hidden]'😉

Quoted message said:

I have recently put a new chain on my road bike, the SRAM PC48.

Now it is almost impossible to change onto the biggest chain ring using
a SORA front dérailleur.

This appears to be because the SRAM chain flexes from side to side more
than the original chain. I can play with the front dérailleur to get
shifting back but I suspect it will always be harder shifting than it
was with the original stiffer chain.

If I bought a more expensive chain (SRAM or otherwise) would it be
stiffer and hence have better front shifting properties.

Also can I use the SRAM powerlinks on other chains. I know TAYA did
something similar but it was a use once design.

I'd be very, very surprised if your problem was the chains - SRAM chains
are generally very good. Is the chain long enough? When you're changing up
onto the big ring, is the rear mech unduly extended?

You certainly can use SRAM magic links with non-SRAM chains, but
the 'speed' of the chain (i.e., width) should be the same as the 'speed'
of the link - i.e. 8 speed with 8 speed, 9 speed with 9 speed.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Let's have a moment of silence for all those Americans who are stuck
;; in traffic on their way to the gym to ride the stationary bicycle.
;; Rep. Earl Blumenauer (Dem, OR)