Replacing my drivetrain

Tom Anderson said:

Hi all,

My chain is rather worn - twelve links measure a bit over a foot and
an eighth of an inch. So, time to kick myself for (a) not looking
after it better and (b) not catching it earlier, and then replace it,
and my sprockets. And at least one chainring.

I have three questions.

Firstly, only one of my chainrings is badly worn (the middle one,
where i lazily spend most of my time). Ideally, i'd replace just that
ring, but i can't find an identical replacement chainring on its own.
It's an SR Suntour XCC (not sure exactly what model), and whilst i
can find a whole unit, with three chainrings and a crank, i can't
find just a chainring. Do separate chainrings exist? Do Suntour make
them? Will another make be compatible? I can get the whole unit for
18.95, and the cheapest lone chainring i can find (a Shimano Deore
M510) is getting on for half that anyway.

You can get separate chainrings from various makers at various prices.
Critical issue is the Pitch Circle Diameter (PCD) and the number of bolts
(typically 4 or 5). For a given PCD and bolt count (almost) all chainrings
are interchangeable.

Yes, its sometimes cheaper to buy a new crankset. That's marketing for you.

Quoted message said:

Secondly, are there any particular components i should seek out or
avoid? FWIW, my bike is an MTB, mostly used for commuting with
occasional trail rides - towpaths, bridleways, and that, nothing
serious. I currently have a SRAM PG950 9-speed cassette, i have no
idea what the chain is, and as i mention above, SR Suntour XCC
chainrings. I was thinking i'd just replace like with like, and get
another PG950, or a PG970, which Wiggle is selling unboxed for the
same price, and a SRAM chain. I'm hazy on the differences between
SRAM chains; a PC971 is only a bit more expensive than a PC951, and
i've read that it wears better, but a PC991 is substantially more
expensive - is it worth it at all? Should be looking to non-SRAM
components?

No reason to use SRAM and no reason to avoid. They are competant components.

I'd get the cheaper chain and change it more frequently !

Quoted message said:

Thirdly, am i likely to be able to change the components myself? Does
it need specialised tools or a lot of skill?

Skill - nothing very complicated, most of it detailed on Park Tools website
help pages.

Tools:

Crankset and chainrings. Probably need tool to remove crankset. If its a
square taper design, then a puller (which screws into the crank) is required
(I think splined types also have pullers). May need a spanner with big
extension bar to get the leverage to work the puller. Once the crankset is
removed, normal allen keys and spanners can remove/replace the rings. You
may be able to replace the rings without removing the crankset (though
unlikely to get the inner one off), but it can be tricky.

Chains. Probably need a chain tool to shorten chain to appropriate number
of links. With SRAM chains, once shortened, you get a quick-link to
make/break the chain by hand.

Rear Cassette. Will require a lock-ring tool (odd castellated socket) to
remove the lockring holding the cassette to the freewheel component
(freehub). The lock-ring tool is specific to maker of cassette, though some
do use same part as others (try Park Tools website to determine which type
you require). Also require a chain-whip to stop the cassette rotating when
undoing the lock-ring, can buy these, or can make your own from decent
length of steel (to form handle) and bit of old chain (you have lots !).

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Nigel Cliffe writtificated

Quoted message said:

Quoted message said:

I'm hazy on the differences between
SRAM chains; a PC971 is only a bit more expensive than a PC951, and
i've read that it wears better, but a PC991 is substantially more
expensive - is it worth it at all? Should be looking to non-SRAM
components?

Last time I investigated chains, the only difference was a teensy bit of
weight and the force needed to break one through misuse. Unless you're
stupidly powerful, enormously heavy or doing crazy stuff, then the
'weakest' SRAM chain is more than strong enough. You had to pay lots more
over the base model before you got into decent weight savings too.

Quoted message said:

No reason to use SRAM and no reason to avoid. They are competant
components.

The reusable SRAM powerlink is what clinches their 5 to 8 speed chains over
Shimano ones. I'm not sure whether 9 speed ones are reusable thobut.

Quoted message said:

I'd get the cheaper chain and change it more frequently !

Yep!

Mark T said:

Nigel Cliffe writtificated

Quoted message said:

Quoted message said:

I'm hazy on the differences between
SRAM chains; a PC971 is only a bit more expensive than a PC951, and
i've read that it wears better, but a PC991 is substantially more
expensive - is it worth it at all? Should be looking to non-SRAM
components?

Last time I investigated chains, the only difference was a teensy bit
of weight and the force needed to break one through misuse.

Finishes can be different as well between one model and another - not
important.

Quoted message said:

Unless
you're stupidly powerful, enormously heavy or doing crazy stuff, then
the 'weakest' SRAM chain is more than strong enough. You had to pay
lots more over the base model before you got into decent weight
savings too.

Quoted message said:

No reason to use SRAM and no reason to avoid. They are competant
components.

The reusable SRAM powerlink is what clinches their 5 to 8 speed
chains over Shimano ones. I'm not sure whether 9 speed ones are
reusable thobut.

They are, and can be used on other makes chain too.

~PB

Tom Anderson said:

Thirdly, am i likely to be able to change the components myself? Does
it need specialised tools or a lot of skill?

If the right-hand crank needs removing to replace the inner ring, or if you
are replacing the whole chainset, it's very important that the cranks are
fitted tightly enough. The conventional (square taper) type need to be done
up more tightly than you might think. I recommend using a torque wrench.
Find more advice on the Sheldon Brown and Park Tools websites.

You'll also need a chain tool to shorten the new chain.

~PB

Nigel Cliffe said:

Tom Anderson said:

Do separate chainrings exist? Do Suntour make them? Will another make
be compatible? I can get the whole unit for 18.95, and the cheapest
lone chainring i can find (a Shimano Deore M510) is getting on for half
that anyway.

You can get separate chainrings from various makers at various prices.
Critical issue is the Pitch Circle Diameter (PCD) and the number of
bolts (typically 4 or 5). For a given PCD and bolt count (almost) all
chainrings are interchangeable.

Okay, that's good news. Now i just need to work out what my pitch circle
diameter is.

Quoted message said:

Yes, its sometimes cheaper to buy a new crankset. That's marketing for
you.

Indeed. It does seem slightly foolish for me to be buying a single
chainring when i could get a complete new set for not a lot more. But
then, it seems highly foolish to be buying components i don't need!

Quoted message said:

Quoted message said:

Secondly, are there any particular components i should seek out or
avoid?

No reason to use SRAM and no reason to avoid. They are competant components.

That's what i thought. The same can be said of Shimano, right? And
Campagnolo? So i've got plenty of choice. Too much choice, in fact!

Quoted message said:

Quoted message said:

I'm hazy on the differences between SRAM chains; a PC971 is only a bit
more expensive than a PC951, and i've read that it wears better, but a
PC991 is substantially more expensive - is it worth it at all? Should
be looking to non-SRAM components?

I'd get the cheaper chain and change it more frequently !

Righto. FWIW, relative to the 951, the 971 is 25% more expensive, and the
991 69%. It seems plausible that the 971 will last 25% longer than the
951, but somehow unlikely that the 991 will last 69% longer. Also, there's
no way i'm paying 27 quid for a chain, that's ridiculous.

Quoted message said:

Quoted message said:

Thirdly, am i likely to be able to change the components myself? Does
it need specialised tools or a lot of skill?

Skill - nothing very complicated, most of it detailed on Park Tools website
help pages.

Tools:

Crankset and chainrings. Probably need tool to remove crankset. If its a
square taper design,

It is.

Quoted message said:

then a puller (which screws into the crank) is required

Not got that.

Quoted message said:

(I think splined types also have pullers). May need a spanner with big
extension bar to get the leverage to work the puller.

Or that.

Quoted message said:

Once the crankset is
removed, normal allen keys and spanners can remove/replace the rings.

Got those!

Quoted message said:

You may be able to replace the rings without removing the crankset
(though unlikely to get the inner one off), but it can be tricky.

Chains. Probably need a chain tool to shorten chain to appropriate number
of links.

Got that, funnily enough; i've got a crazy old multi-tool with a chain
tool built into the spanner handle.

Quoted message said:

With SRAM chains, once shortened, you get a quick-link to make/break the
chain by hand.

Yes. Which, thinking about it, means my current chain probably isn't SRAM,
as it doesn't seem to have such a thing.

Quoted message said:

Rear Cassette. Will require a lock-ring tool (odd castellated socket)
to remove the lockring holding the cassette to the freewheel component
(freehub). The lock-ring tool is specific to maker of cassette, though
some do use same part as others (try Park Tools website to determine
which type you require).

Well, whichever one i need, not got it!

Quoted message said:

Also require a chain-whip to stop the cassette rotating when
undoing the lock-ring,

Not got that either.

Quoted message said:

can buy these, or can make your own from decent length of steel (to form
handle) and bit of old chain (you have lots !).

Ha! Quite true!

Okay, it sounds like either i go to the LBS, i spend quite a bit on tools,
or i find someone i can borrow them off. I know there's a collective
bicycle repair workshop run by some lovely radical type people somewhere
in east London; i might go and see if i can borrow some of their tools.

Cheers for the info!

tom

--
All bloggers must die.

Pete Biggs said:

Mark T said:

Nigel Cliffe writtificated

Quoted message said:

> I'm hazy on the differences between SRAM chains; a PC971 is only a
> bit more expensive than a PC951, and i've read that it wears better,
> but a PC991 is substantially more expensive - is it worth it at all?
> Should be looking to non-SRAM components?

Last time I investigated chains, the only difference was a teensy bit
of weight and the force needed to break one through misuse.

Finishes can be different as well between one model and another - not
important.

Yes, having looked this up, it seems that the only difference is that the
951 is unplated, the 971 has nickel-plated outer plates, and the 991 is
fully nickel-coated. The nickel coating makes it shinier and more
rust-resistant, but since my chain is always covered in a layer of oil,
neither of those really matter, so i guess a 951 is the most sensible
choice.

tom

--
All bloggers must die.

Pete Biggs said:

Tom Anderson said:

Thirdly, am i likely to be able to change the components myself? Does
it need specialised tools or a lot of skill?

If the right-hand crank needs removing to replace the inner ring, or if
you are replacing the whole chainset, it's very important that the
cranks are fitted tightly enough. The conventional (square taper) type
need to be done up more tightly than you might think. I recommend using
a torque wrench.

I'll add that to my list of tools to find 🙁.

tom

--
All bloggers must die.

In article <[email hidden]>, Tom
Anderson
[email hidden] says...

Quoted message said:

Nigel Cliffe said:

Tom Anderson said:

Do separate chainrings exist? Do Suntour make them? Will another make
be compatible? I can get the whole unit for 18.95, and the cheapest
lone chainring i can find (a Shimano Deore M510) is getting on for half
that anyway.

You can get separate chainrings from various makers at various prices.
Critical issue is the Pitch Circle Diameter (PCD) and the number of
bolts (typically 4 or 5). For a given PCD and bolt count (almost) all
chainrings are interchangeable.

Okay, that's good news. Now i just need to work out what my pitch circle
diameter is.

Are you sure the rings are removable? The information I found suggests
that they're riveted on.

Quoted message said:

Quoted message said:

Yes, its sometimes cheaper to buy a new crankset. That's marketing for
you.

Indeed. It does seem slightly foolish for me to be buying a single
chainring when i could get a complete new set for not a lot more. But
then, it seems highly foolish to be buying components i don't need!

You could buy a whole new bike for less than the cost of a good chainset
- guess which would last longer.

In article <[email hidden]>, Tom
Anderson
[email hidden] says...

Quoted message said:

Yes, having looked this up, it seems that the only difference is that the
951 is unplated, the 971 has nickel-plated outer plates, and the 991 is
fully nickel-coated. The nickel coating makes it shinier and more
rust-resistant, but since my chain is always covered in a layer of oil,
neither of those really matter, so i guess a 951 is the most sensible
choice.

You shouldn't have oil on the outside of the chain - all it does is
attract grit, which soon makes an effective grinding paste (as you
appear to have discovered already).

Rob Morley said:

In article <[email hidden]>, Tom
Anderson
[email hidden] says...

Quoted message said:

Yes, having looked this up, it seems that the only difference is
that the 951 is unplated, the 971 has nickel-plated outer plates,
and the 991 is fully nickel-coated. The nickel coating makes it
shinier and more rust-resistant, but since my chain is always
covered in a layer of oil, neither of those really matter, so i
guess a 951 is the most sensible choice.

You shouldn't have oil on the outside of the chain - all it does is
attract grit, which soon makes an effective grinding paste (as you
appear to have discovered already).

You can try to minimise the amount, but if using oil at all, you can't stop
some oozing from the inside to the outside. This is normally enought to
prevent rust.

~PB

Tom Anderson said:

Nigel Cliffe said:

You can get separate chainrings from various makers at various
prices. Critical issue is the Pitch Circle Diameter (PCD) and the
number of bolts (typically 4 or 5). For a given PCD and bolt count
(almost)
all chainrings are interchangeable.

Okay, that's good news. Now i just need to work out what my pitch
circle diameter is.

Pitch Circle Diameter = Bolt Circle Diameter

There's a table here to work out the BCD from a simple measurement:

http://www.sheldonbrown.com/gloss_bo-z.html

Quoted message said:

Quoted message said:

Yes, its sometimes cheaper to buy a new crankset. That's marketing
for you.

Indeed. It does seem slightly foolish for me to be buying a single
chainring when i could get a complete new set for not a lot more.

Unless you want a combination of sizes not available as a chainset off the
shelf. That can be worth paying for.

~PB

Pete Biggs said:

Rob Morley said:

In article <[email hidden]>, Tom
Anderson
[email hidden] says...

Quoted message said:

Yes, having looked this up, it seems that the only difference is
that the 951 is unplated, the 971 has nickel-plated outer plates,
and the 991 is fully nickel-coated. The nickel coating makes it
shinier and more rust-resistant, but since my chain is always
covered in a layer of oil, neither of those really matter, so i
guess a 951 is the most sensible choice.

You shouldn't have oil on the outside of the chain - all it does is
attract grit, which soon makes an effective grinding paste (as you
appear to have discovered already).

Indeed i have! In addition to buying new bits, i am going to be mending my
ways when it comes to cleaning and lubrication. More white spirit, less
oil.

Quoted message said:

You can try to minimise the amount, but if using oil at all, you can't
stop some oozing from the inside to the outside. This is normally
enought to prevent rust.

This is what i'm hoping.

tom

--
All London roads are part of MY London Cycle Network. I'd like to see
some of them removed from the London Motor Network! -- Ben Jefferys

Pete Biggs said:

Tom Anderson said:

Nigel Cliffe said:

You can get separate chainrings from various makers at various prices.
Critical issue is the Pitch Circle Diameter (PCD) and the number of
bolts (typically 4 or 5). For a given PCD and bolt count (almost) all
chainrings are interchangeable.

Okay, that's good news. Now i just need to work out what my pitch
circle diameter is.

Pitch Circle Diameter = Bolt Circle Diameter

There's a table here to work out the BCD from a simple measurement:

http://www.sheldonbrown.com/gloss_bo-z.html

Very good. Although for four-bolt setups, you might as well measure the
diameter directly, rather than measuring one side and multiplying by the
square root of two!

But as Mr Morley says, mine might be riveted anyway, which would explain
why i haven't found the rings on their own.

tom

--
All London roads are part of MY London Cycle Network. I'd like to see
some of them removed from the London Motor Network! -- Ben Jefferys

Tom Anderson said:

Quoted message said:

There's a table here to work out the BCD from a simple measurement:

http://www.sheldonbrown.com/gloss_bo-z.html

Very good. Although for four-bolt setups, you might as well measure
the diameter directly, rather than measuring one side and multiplying
by the square root of two!

Measuring the diameter is not easy while the ring is fitted to the crank.
No calculations required because Sheldon already did the sums for us. Just
measure the distance from one bolt to the next and look up the table.

Quoted message said:

But as Mr Morley says, mine might be riveted anyway, which would
explain why i haven't found the rings on their own.

Yes, check for allen key (or torx?) heads first. No point in measuring if
you can't get 'em off.

~PB

In article <[email hidden]>, Pete Biggs
[email hidden] says...

Quoted message said:

Tom Anderson said:

Quoted message said:

There's a table here to work out the BCD from a simple measurement:

http://www.sheldonbrown.com/gloss_bo-z.html

Very good. Although for four-bolt setups, you might as well measure
the diameter directly, rather than measuring one side and multiplying
by the square root of two!

Measuring the diameter is not easy while the ring is fitted to the crank.

It is if you have one of these: http://www.fine-tools.com/st306461a.jpg

Rob Morley said:

Quoted message said:

Measuring the diameter is not easy while the ring is fitted to the
crank.

It is if you have one of these:
http://www.fine-tools.com/st306461a.jpg

Don't tempt me with any more goodies, please :-)

~PB

Pete Biggs said:

Tom Anderson said:

Quoted message said:

There's a table here to work out the BCD from a simple measurement:

http://www.sheldonbrown.com/gloss_bo-z.html

Very good. Although for four-bolt setups, you might as well measure
the diameter directly, rather than measuring one side and multiplying
by the square root of two!

Measuring the diameter is not easy while the ring is fitted to the crank.

Doh! Point taken.

Quoted message said:

No calculations required because Sheldon already did the sums for us. Just
measure the distance from one bolt to the next and look up the table.

Quoted message said:

But as Mr Morley says, mine might be riveted anyway, which would
explain why i haven't found the rings on their own.

Yes, check for allen key (or torx?) heads first. No point in measuring
if you can't get 'em off.

No sign of anything allenable, so yes, it's riveted. Which solves the
problem - can't buy a lone ring, and there's no point spending 50 quid or
whatever on a proper bolted crankset when i can get another riveted one
for under 20, so i'll just get a complete replacement. Boo!

tom

--
At Forkmeeter in 12478, the Wracket Dispersal had reached the first
limit of its bounding eastward rush.

In article <[email hidden]>, Pete Biggs
[email hidden] says...

Quoted message said:

Rob Morley said:

Quoted message said:

Measuring the diameter is not easy while the ring is fitted to the
crank.

It is if you have one of these:
http://www.fine-tools.com/st306461a.jpg

Don't tempt me with any more goodies, please :-)

You can easily make simple calipers by cutting a couple of pieces of
steel and bolting them together with spring washers - should be good to
about 0.1mm if you use them carefully, which is as good as you need for
bike mechanicing. Obviously the proper flat ones use spring steel, and
the lockable ones are easier to use.

http://img.tfd.com/wn/5C/630CD-outside-caliper.gif

http://img.tfd.com/wn/46/62C68-inside-caliper.gif