'Rumbly' fixer

Mark wrote on 05/04/2007 10:12 +0100:

Quoted message said:

Hi

I replaced the chain on my fixer at the weekend after losing a roller
when cleaning the old one which, aside from being a bit rusty, didn't
appear to be at all worn. 24 links measured a small fraction over 12";
impressive after a winter of riding and a relatively relaxed attitude
to cleaning.

Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
chainring a nice Stronglight duralim (or whatever it is), both 3/32".
Since replacing the chain I've had a strange rumbling vibration
through the cranks, somewhat like the chain is binding. It's not,
though. For whatever reason there is a considerable variation in chain
tension but it is never completely taught (I've tried replacing the
ring and adjusting it on the spider). There's probably a centimetre of
slack in the most taught configuration. This is about the same as it
was with the old chain.

Too narrow a chain? I usually use a 1/8" chain on the fixed.

--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell

Mark said:

Hi

I replaced the chain on my fixer at the weekend after losing a roller
when cleaning the old one which, aside from being a bit rusty, didn't
appear to be at all worn. 24 links measured a small fraction over 12";
impressive after a winter of riding and a relatively relaxed attitude
to cleaning.

Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
chainring a nice Stronglight duralim (or whatever it is), both 3/32".
Since replacing the chain I've had a strange rumbling vibration
through the cranks, somewhat like the chain is binding. It's not,
though. For whatever reason there is a considerable variation in chain
tension but it is never completely taught (I've tried replacing the
ring and adjusting it on the spider). There's probably a centimetre of
slack in the most taught configuration. This is about the same as it
was with the old chain.

I suspect the problems (rumbling and inconsistent tension) may be to
do with the small amount of play in the bottom bracket, though why
it's taken a new chain to produce the vibration is a mystery. The
frame is a 1970s Viscount which I believe has some kind of fruity
threadless bottom bracket. I've never tried to take it out so I don't
know for certain but externally it looks like nothing I've seen
before. It has a large grey protusion on each side (plastic, perhaps)
and the cranks are held on with a nut rather than a bolt, if this
helps identify it. Any ideas on what it is, whether I can replace it
and whether replacing it will fix my problems?

Thanks!

Mark

Worn sprocket? Loosing a roller is a true sign af a chain being shot.

I've had a Viscount BB tapped to Italian once. But before spending money
check the shape it's in, mine died through internal corrosion,
presumably by leaving the flux inside

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Mark <[email hidden]> waffled thusly

Quoted message said:

I suspect the problems (rumbling and inconsistent tension) may be to
do with the small amount of play in the bottom bracket,

Almost certainly.

Quoted message said:

though why
it's taken a new chain to produce the vibration is a mystery.

Maybe the old chain, having more play simply masked the noise and rumble?

Quoted message said:

The
frame is a 1970s Viscount which I believe has some kind of fruity
threadless bottom bracket. I've never tried to take it out so I don't
know for certain but externally it looks like nothing I've seen
before. It has a large grey protusion on each side (plastic, perhaps)
and the cranks are held on with a nut rather than a bolt, if this
helps identify it. Any ideas on what it is, whether I can replace it
and whether replacing it will fix my problems?

IIRC (mate had a Viscount, lovely bike) they did use a threadless bottom
bracket with cartridge bearings, held in with circlips and a cover. I have
no clue where you'd get one now though.

Might be worth taking a few measurements and googling or searching local
lbs'

--
Paul - [censored]

Tony Raven said:

Mark wrote on 05/04/2007 10:12 +0100:

Quoted message said:

Hi

I replaced the chain on my fixer at the weekend

Quoted message said:

Quoted message said:

Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
chainring a nice Stronglight duralim (or whatever it is), both 3/32".
Since replacing the chain I've had a strange rumbling vibration
through the cranks, somewhat like the chain is binding. It's not,
though. For whatever reason there is a considerable variation in chain
tension but it is never completely taught (I've tried replacing the
ring and adjusting it on the spider). There's probably a centimetre of
slack in the most taught configuration. This is about the same as it
was with the old chain.

It's a shame we can't teach spurlechucklers to differentiate between
homophones :-)

Quoted message said:

Too narrow a chain? I usually use a 1/8" chain on the fixed.

I'd use a chain that fitted the chainring and sprocket.

I'd say to ditch the cheap sprocket for something less cheap and
nasty. Shimano do nice Dura-Ace ones in 3/32 inch for about 12 quid.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

Phil Cook said:

Tony Raven said:

Mark wrote on 05/04/2007 10:12 +0100:

Quoted message said:

Hi

Quoted message said:

Quoted message said:

I replaced the chain on my fixer at the weekend
Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
chainring a nice Stronglight duralim (or whatever it is), both 3/32".
Since replacing the chain I've had a strange rumbling vibration
through the cranks, somewhat like the chain is binding. It's not,
though. For whatever reason there is a considerable variation in chain
tension but it is never completely taught (I've tried replacing the
ring and adjusting it on the spider). There's probably a centimetre of
slack in the most taught configuration. This is about the same as it
was with the old chain.

It's a shame we can't teach spurlechucklers to differentiate between
homophones :-)

Alright smartarse. I thought something about 'taught' looked funny but
couldn't be bothered to verify it.

Quoted message said:

Quoted message said:

Too narrow a chain? I usually use a 1/8" chain on the fixed.

I'd use a chain that fitted the chainring and sprocket.

I'd say to ditch the cheap sprocket for something less cheap and
nasty. Shimano do nice Dura-Ace ones in 3/32 inch for about 12 quid.

The taut (happy?) spot seems to depend on the crank position, hence my
BB query. Changing the sprocket is much less hassle than the BB,
though. I'll have a go.

Mark

Mark said:

Phil Cook said:

Tony Raven said:

Mark wrote on 05/04/2007 10:12 +0100:
> Hi

Quoted message said:

> I replaced the chain on my fixer at the weekend
> Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
> cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
> chainring a nice Stronglight duralim (or whatever it is), both 3/32".
> Since replacing the chain I've had a strange rumbling vibration
> through the cranks, somewhat like the chain is binding. It's not,
> though. For whatever reason there is a considerable variation in chain
> tension but it is never completely taught (I've tried replacing the
> ring and adjusting it on the spider). There's probably a centimetre of
> slack in the most taught configuration. This is about the same as it
> was with the old chain.

It's a shame we can't teach spurlechucklers to differentiate between
homophones :-)

Alright smartarse. I thought something about 'taught' looked funny but
couldn't be bothered to verify it.

Sorry I couldn't resist, especially working "teach" into the reply.
:-0

Quoted message said:

Quoted message said:

Quoted message said:

Too narrow a chain? I usually use a 1/8" chain on the fixed.

I'd use a chain that fitted the chainring and sprocket.

I'd say to ditch the cheap sprocket for something less cheap and
nasty. Shimano do nice Dura-Ace ones in 3/32 inch for about 12 quid.

The taut (happy?) spot seems to depend on the crank position, hence my
BB query. Changing the sprocket is much less hassle than the BB,
though. I'll have a go.

Well it may well be a combination of crank, sprocket and BB condition.
But I remember when I had a cheap pressed sprocket it was a devil of a
job to get the chain to run smooth.

There are a few BBs out there that will fit frames without threads
(the BB shell has to be faced at 45 degrees) but they seem expensive.
I'd say you would be better off looking for another frame. But short
of that SJS do have the bearings for sale.
http://www.sjscycles.co.uk/category-Sealed-Cartridges-429.htm
--
Phil Cook looking north over the park to the "Westminster Gasworks"

On Apr 5, 10:49 pm, Phil Cook <[email hidden]> wrote:

<bottom bracket woes>

Quoted message said:

There are a few BBs out there that will fit frames without threads
(the BB shell has to be faced at 45 degrees) but they seem expensive.
I'd say you would be better off looking for another frame. But short
of that SJS do have the bearings for sale.http://www.sjscycles.co.uk/category-Sealed-Cartridges-429.htm

A quick glance suggests those are bog standard industrial bearings.
Take the old ones out, go to your local bearing supplier and ask for
replacements. Then pay less than half what that nice Mr. Thorn would
have you pay.

Tim, on Google Groups

Mark said:

Hi

I replaced the chain on my fixer at the weekend after losing a roller
when cleaning the old one which, aside from being a bit rusty, didn't
appear to be at all worn. 24 links measured a small fraction over 12";
impressive after a winter of riding and a relatively relaxed attitude
to cleaning.

Anyway, I digress. The new chain is a SRAM PC58 and the old one was a
cheapo 8sp jobbie (KMC?). The sprocket is a cheap steel job, the
chainring a nice Stronglight duralim (or whatever it is), both 3/32".
Since replacing the chain I've had a strange rumbling vibration
through the cranks, somewhat like the chain is binding. It's not,
though. For whatever reason there is a considerable variation in chain
tension but it is never completely taught (I've tried replacing the
ring and adjusting it on the spider). There's probably a centimetre of
slack in the most taught configuration. This is about the same as it
was with the old chain.

I suspect the problems (rumbling and inconsistent tension) may be to
do with the small amount of play in the bottom bracket, though why
it's taken a new chain to produce the vibration is a mystery. The
frame is a 1970s Viscount which I believe has some kind of fruity
threadless bottom bracket. I've never tried to take it out so I don't
know for certain but externally it looks like nothing I've seen
before. It has a large grey protusion on each side (plastic, perhaps)
and the cranks are held on with a nut rather than a bolt, if this
helps identify it. Any ideas on what it is, whether I can replace it
and whether replacing it will fix my problems?

Some chains are less tolerant of poor chainline than others, the most
fussy being proper track chains with full bushings and no sideways slop.
Both the KMC and SRAM chains are bushingless, but the KMC probably had
more slop than the SRAM, especially when worn. Do you know if your
chainline is within 1mm F/R?

Tim Hall said:

On Apr 5, 10:49 pm, Phil Cook <[email hidden]> wrote:

<bottom bracket woes>

Quoted message said:

There are a few BBs out there that will fit frames without threads
(the BB shell has to be faced at 45 degrees) but they seem expensive.
I'd say you would be better off looking for another frame. But short
of that SJS do have the bearings for
sale.http://www.sjscycles.co.uk/category-Sealed-Cartridges-429.htm

A quick glance suggests those are bog standard industrial bearings.
Take the old ones out, go to your local bearing supplier and ask for
replacements. Then pay less than half what that nice Mr. Thorn would
have you pay.

http://www.unifit.co.uk/default.cfm?FromRec=41&result&make=1&categoryid=6&subcat=999 £4.37 each (or £12 from SJS) Or get 4 for £7 from ebayhttp://cgi.ebay.co.uk/motorcycle-motorcross-wheel-bearings-6003-2rs-4-off_W0QQitemZ330105469685QQcategoryZ10460QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Tom--Return address is dead. Real address is athttp://www.happy-penguin.info/address.jpg

Zog The Undeniable said:

Mark said:

[vibration with new chain on fixer]

Some chains are less tolerant of poor chainline than others, the most
fussy being proper track chains with full bushings and no sideways slop.
Both the KMC and SRAM chains are bushingless, but the KMC probably had
more slop than the SRAM, especially when worn. Do you know if your
chainline is within 1mm F/R?

Crikey. I'd be surprised if it was that good. From behind it looks
pretty straight and I've never had a problem with the chain coming off
(yet..) but I've never measured it. That sounds like a pretty
reasonable reason for my problems and makes me wish I'd just gone for
another cheapo chain!

Tom: thanks for the BB links, I'll check them out.

Mark