Chainring compatibility

Tom Anderson said:

Hello!

I'm very confused about chainrings. This is a combination of ignorance
and a cold.

You if you are going for a larger chainset, you might also need to
replace the front mech as well.

If I were going to do what you are suggesting, I would purchase the same
make of chainrings and chainset, just to make sure about compatibility.

Tom Anderson said:

Hello!

I'm very confused about chainrings. This is a combination of
ignorance and a cold.

I have a mountain bike, which i have never taken anywhere near a
mountain, unless you count Muswell Hill,

I do.

Quoted message said:

or possibly the hills to the
north of Exeter. I ride it to work mostly. It's got triple chainrings
and a 9-speed cassette, both of which i need to replace. The
chainrings are in the shape of a one-piece rivetted Suntour unit, so
i'm replacing the entire crankset (with something with bolts).

I'm planning to replace the cassette like-for-like, 11-32 or 11-34 or
something.

I could get a straight replacement for my current crankset, ie
something with 22/32/44 rings, like one of these:

http://wiggle.co.uk/ProductDetail.aspx?Cat=cycle&ProdID=5360029483&n=Shimano%20Shimano%20M442%20Mega9%20Tapered%20Chainset
http://wiggle.co.uk/ProductDetail.aspx?Cat=cycle&ProdID=5360029463&n=FSA%20FSA%20Alpha%20Drive%20ATB%20ISIS%20Chainset

But given the lack of actual mountains on my typical rides, i was
thinking i might get something a bit more tourer-like. I was thinking
of a 38-tooth middle ring, and then i suppose a 48-tooth big. Still
with the 22-tooth little ring for when i do find steep hills, if that
makes any sense (22 to 38 - yikes).

Not a bad idea in theory, but you will find 24-38-48 more practical in terms
of derailleur setting up and performance, and crankset compatibility. 24t
is the minimum that will fit 74mm that Shimano and Campagnolo road triple
chainsets use, for example.

Quoted message said:

I can't find a crankset that comes with a configuration like that.
They probably exist, but i couldn't track any down. No matter,
though, i can just buy a suitable middle (and possibly big) ring and
fit it.
This is where the confusion sets in. How do i know if a chainring is
going to be compatible? I can tell if it's got the right number of
bolt holes, and that it has a compatible bolt circle diameter. But do
chainrings vary in their suitability for use in a triple,

Rings designed for doubles can be fitted to triple chainsets when the BCD is
compatible. There are middle-specific rings that have ramps and pins to
help the chain shift up from the inner ring. See the TA ones from
www.dotbike.com. These are not always necessary, though, depending on your
shifters and mechs and what you're prepared to tolerate.

Quoted message said:

and with a 9-speed back end?

Any 7, 8 or 9 speed chainset would be fine with a 9-speed chain. A 10-speed
one would be too, though sometimes chainring spacers (washers) are needed to
prevent rubbing in certain reasonable gear combinations.

Quoted message said:

I'm starting to think i might be better off with a 22/32/44 crankset,
and a road cassette, purely because it's more comprehensible. That
would let me use a medium-cage mech, too, which i have heard might
give me better shifting.

The important things to decide first are the bottom gear you want, and the
size of the jumps between the rear gears. The rest then can and will be
compromised by component availability and limitations.

~PB

Martin said:

Tom Anderson said:

I'm very confused about chainrings. This is a combination of ignorance and
a cold.

You if you are going for a larger chainset, you might also need to replace
the front mech as well.

good point. bugger.

Quoted message said:

If I were going to do what you are suggesting, I would purchase the same
make of chainrings and chainset, just to make sure about compatibility.

ah, but where's the fun in that?

tom

--
102 FX 6 (goblins)

Pete Biggs said:

Tom Anderson said:

But given the lack of actual mountains on my typical rides, i was
thinking i might get something a bit more tourer-like. I was thinking
of a 38-tooth middle ring, and then i suppose a 48-tooth big. Still
with the 22-tooth little ring for when i do find steep hills, if that
makes any sense (22 to 38 - yikes).

Not a bad idea in theory, but you will find 24-38-48 more practical in
terms of derailleur setting up and performance, and crankset
compatibility. 24t is the minimum that will fit 74mm that Shimano and
Campagnolo road triple chainsets use, for example.

Aha. I'd been thinking in terms of fitting big rings on a 104/64 MTB
spider, but a road version might make more sense.

Quoted message said:

Quoted message said:

This is where the confusion sets in. How do i know if a chainring is
going to be compatible? I can tell if it's got the right number of bolt
holes, and that it has a compatible bolt circle diameter. But do
chainrings vary in their suitability for use in a triple,

Rings designed for doubles can be fitted to triple chainsets when the
BCD is compatible. There are middle-specific rings that have ramps and
pins to help the chain shift up from the inner ring. See the TA ones
from www.dotbike.com. These are not always necessary, though, depending
on your shifters and mechs and what you're prepared to tolerate.

Righto.

Quoted message said:

Quoted message said:

and with a 9-speed back end?

Any 7, 8 or 9 speed chainset would be fine with a 9-speed chain. A
10-speed one would be too, though sometimes chainring spacers (washers)
are needed to prevent rubbing in certain reasonable gear combinations.

Okay.

I take it that if a crankset says it's 8-speed, it's not going to work
well with a 9-speed cassette?

Quoted message said:

Quoted message said:

I'm starting to think i might be better off with a 22/32/44 crankset,
and a road cassette, purely because it's more comprehensible. That
would let me use a medium-cage mech, too, which i have heard might
give me better shifting.

The important things to decide first are the bottom gear you want, and
the size of the jumps between the rear gears. The rest then can and
will be compromised by component availability and limitations.

Fair enough.

Anyway, it turns out there are basically no 9-speed cranksets in the size
range i want which fit a square tapered bottom bracket - nobody makes one,
full stop. So, perhaps time for a new bottom bracket, which means a new
post ...

tom

--
102 FX 6 (goblins)

Tom Anderson said:

I take it that if a crankset says it's 8-speed, it's not going to work
well with a 9-speed cassette?

It will work fine. The crankset doesn't know or care what cassette you have
on the bike. You can use a 9-speed chain on an 8-speed chainset because the
*internal* width (size of holes in middle) of 7, 8, 9 and 10-speed chains is
about the same.

/snip

Quoted message said:

Anyway, it turns out there are basically no 9-speed cranksets in the
size range i want

Does that mean with an inner ring smaller than 24t? Otherwise I'm sure you
could find one that could take 24/39/48. 8 and 10-speed cranks would be OK
too.

Quoted message said:

which fit a square tapered bottom bracket - nobody
makes one, full stop. So, perhaps time for a new bottom bracket,
which means a new post ...

You might need to change the BB anyway even if the new cranks fit a square
taper. Different cranks require different axle lengths, and there are two
standards of square taper.

As mentioned by another poster, you will need to think about the front
derailleur too and what size rings it can cope with. If you change the
front mech, then you need to think about compatibility with the shifter as
well.

Have you thought about getting a whole new bike? ;-)

~PB

Pete Biggs said:

Tom Anderson said:

I take it that if a crankset says it's 8-speed, it's not going to work
well with a 9-speed cassette?

It will work fine. The crankset doesn't know or care what cassette you
have on the bike. You can use a 9-speed chain on an 8-speed chainset
because the *internal* width (size of holes in middle) of 7, 8, 9 and
10-speed chains is about the same.

Ah, so it's to do with the size of the chain, rather than anything about
alignment of the chainrings and sprockets? You can use any combination of
an N-speed crankset, M-speed cassette and P-speed chain as long as P >= N
and P >= M?

Quoted message said:

Quoted message said:

Anyway, it turns out there are basically no 9-speed cranksets in the
size range i want

Does that mean with an inner ring smaller than 24t? Otherwise I'm sure
you could find one that could take 24/39/48. 8 and 10-speed cranks
would be OK too.

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage. But if the 8-speed ones work, then fine, no
problem.

Quoted message said:

Quoted message said:

which fit a square tapered bottom bracket - nobody makes one, full
stop. So, perhaps time for a new bottom bracket, which means a new post
...

You might need to change the BB anyway even if the new cranks fit a
square taper. Different cranks require different axle lengths, and
there are two standards of square taper.

Are they different enough that it's really a problem? I have SR Suntour
cranks now, so i assume a JIS BB; Shimano will fit that, but what about
Truvativ? Aaargh ...

Quoted message said:

As mentioned by another poster, you will need to think about the front
derailleur too and what size rings it can cope with. If you change the
front mech, then you need to think about compatibility with the shifter
as well.

Have you thought about getting a whole new bike? ;-)

*SOB*

tom

--
102 FX 6 (goblins)

Tom Anderson said:

Pete Biggs said:

Tom Anderson said:

I take it that if a crankset says it's 8-speed, it's not going to
work well with a 9-speed cassette?

It will work fine. The crankset doesn't know or care what cassette
you have on the bike. You can use a 9-speed chain on an 8-speed
chainset because the *internal* width (size of holes in middle) of
7, 8, 9 and 10-speed chains is about the same.

Ah, so it's to do with the size of the chain, rather than anything
about alignment of the chainrings and sprockets?

Yes, because aligment is pretty much the same with 7 to 10-speed systems.
Although the question does make me wonder about using a road chainset on an
MTB. An alternative BB would fix that *if* it was a problem anyway. (Road
chainsets tend tobe designed for 130mm hubs, MTB for 135mm).

Quoted message said:

You can use any
combination of an N-speed crankset, M-speed cassette and P-speed
chain as long as P >= N and P >= M?

P <=> N and P>= M

Quoted message said:

Quoted message said:

Quoted message said:

Anyway, it turns out there are basically no 9-speed cranksets in the
size range i want

Does that mean with an inner ring smaller than 24t? Otherwise I'm
sure you could find one that could take 24/39/48. 8 and 10-speed
cranks would be OK too.

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage.

Campag and most Shimano road triples can take rings of that size (or 39t
middle for Campag), and I bet someone somewhere has a 9-speed model for
sale. Replacement rings are available. Selling the original rings would
help pay for them.

Quoted message said:

But if the 8-speed ones work, then fine, no problem.

Yep. And 10-speed (though possibly requiring spacers).

Quoted message said:

Quoted message said:

You might need to change the BB anyway even if the new cranks fit a
square taper. Different cranks require different axle lengths, and
there are two standards of square taper.

Are they different enough that it's really a problem?

Can be, yes.

I dunno about Truativ's.

/snip

Quoted message said:

Quoted message said:

Have you thought about getting a whole new bike? ;-)

*SOB*

Seriously, it's very satisfiying to finally have gears that really suit you
(and it's worth some trial and error too), so don't give up your ideas yet.

~PB

Tom Anderson said:

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage. But if the 8-speed ones work, then fine, no
problem.

Here we go, I found one at the very first place I looked up:

http://www.dotbike.com/ProductsP2013.aspx?TRACK%3dDDI

This may not necessarily be the best or cheapest for your bike, but it is a
9-speed square-taper job that can take 24/39/48 rings. See the TA 135 and
74mm rings on that site. They costalot but last well. You will need to
change your BB, but suitable BBs are cheap.

You would increase chance of compatibility with existing front mech if using
an even smaller big ring, say 46t. You could freewheel down Muswell Hill!

Note. I only go on about road bike stuff so much because that's what I know
best.

~PB

In news:[email hidden],
Tom Anderson <[email hidden]> tweaked the Babbage-Engine to tell us:

Quoted message said:

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage.

TA Carmina / Vega and Middleburn, to name but two, can be mixed 'n' matched
to get just about any combination of rings under the sun, though cheap they
are not. I haz a 20-36-48 TA Carmina on one of the Fleet.

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
A complimentary biro(tm) is /not/ to be sniffed at.

Pete Biggs said:

Tom Anderson said:

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage. But if the 8-speed ones work, then fine,
no problem.

Here we go, I found one at the very first place I looked up:

http://www.dotbike.com/ProductsP2013.aspx?TRACK%3dDDI

This may not necessarily be the best or cheapest for your bike, but
it is a 9-speed square-taper job that can take 24/39/48 rings.

Someone can correct this if I'm wrong, but I thought that Campag square
taper is subtly different to Shimano square taper, so theoretically each
needs different bottom bracket.

- Nigel

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

In article said:

Someone can correct this if I'm wrong, but I thought that Campag square
taper is subtly different to Shimano square taper, so theoretically each
needs different bottom bracket.

http://www.sheldonbrown.com/bbtaper.html has the details

On 04 Jun 2008 13:14:21 +0100 (BST), [email hidden]
(Alan Braggins) said in
<[email hidden]>:

Quoted message said:

http://www.sheldonbrown.com/bbtaper.html has the details

Such a shame that we can no longer perform the Summoning and get the
answer from the great man himself.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

Pete Biggs said:

Tom Anderson said:

Pete Biggs said:

Tom Anderson wrote:

> I take it that if a crankset says it's 8-speed, it's not going to
> work well with a 9-speed cassette?

It will work fine. The crankset doesn't know or care what cassette
you have on the bike. You can use a 9-speed chain on an 8-speed
chainset because the *internal* width (size of holes in middle) of
7, 8, 9 and 10-speed chains is about the same.

Ah, so it's to do with the size of the chain, rather than anything
about alignment of the chainrings and sprockets?

Yes, because aligment is pretty much the same with 7 to 10-speed systems.
Although the question does make me wonder about using a road chainset on an
MTB. An alternative BB would fix that *if* it was a problem anyway. (Road
chainsets tend tobe designed for 130mm hubs, MTB for 135mm).

Quoted message said:

You can use any
combination of an N-speed crankset, M-speed cassette and P-speed
chain as long as P >= N and P >= M?

P <=> N and P>= M

P <=> N?

And presumably N <=> M?

That would mean describing a crankset as '9-speed' meant nothing at all.

Did you mean P >= N and N <=> M?

Quoted message said:

Quoted message said:

Quoted message said:

Have you thought about getting a whole new bike? ;-)

*SOB*

Seriously, it's very satisfiying to finally have gears that really suit
you (and it's worth some trial and error too), so don't give up your
ideas yet.

Cheers, i'm trying to stay strong!

tom

--
20 Minutes into the Future

Pete Biggs said:

Tom Anderson said:

I could not find a 24/38/48 or similar, in 9-speed, to fit a square
tapered BB. Not a sausage. But if the 8-speed ones work, then fine, no
problem.

Here we go, I found one at the very first place I looked up:

http://www.dotbike.com/ProductsP2013.aspx?TRACK%3dDDI

This may not necessarily be the best or cheapest for your bike, but it is a
9-speed square-taper job that can take 24/39/48 rings.

Ah, "can take" rather than "has" - i meant that i couldn't find what i
wanted ready-made. I'm now coming to accept that this is how it will be,
though.

Although this:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14479&pRef=45968&vertical=1&v=VARFCT303

Is pretty close, and cheap. If it works with a 9-speed back end, a 24
small would make that just what i wanted. Except BUGGER, i think it's
rivetted.

Okay, this:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=69972&vertical=1&v=VARFCM410

This isn't far off either:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=83706&vertical=1&v=VARFCM532

Both of those presumably fit a JIS square BB, and are in ideologically
pure 104/64 BCD, rather than any kind of overgrown road madness 🙂.

Quoted message said:

Note. I only go on about road bike stuff so much because that's what I know
best.

Fair enough!

tom

--
20 Minutes into the Future

Tom Anderson said:

Quoted message said:

Quoted message said:

You can use any
combination of an N-speed crankset, M-speed cassette and P-speed
chain as long as P >= N and P >= M?

P <=> N and P>= M

P <=> N?

And presumably N <=> M?

That would mean describing a crankset as '9-speed' meant nothing at
all.

It does mean almost nothing to completely nothing in practice. Welcome to
the clashing worlds of marketing and bike customisation. If there are any
dimensional differences between a chainset of one speed and another, they
will be small and usually of no noticeable consequence.

In a rare case where the chainrings close enough together that they cause
chain rub in certain gears on a certain bike with a certain chain, you can
just space the rings further apart with thin washers.

Even *brakes* are sometimes described as "9 speed"! As if they couldn't be
used with 8 or 10-speed systems! Actually it's just because they're part of
a 9-speed groupset and visually match the other components.

~PB

Tom Anderson said:

Okay, this:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=69972&vertical=1&v=VARFCM410

This isn't far off either:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=83706&vertical=1&v=VARFCM532

Both of those presumably fit a JIS square BB, and are in ideologically
pure 104/64 BCD, rather than any kind of overgrown road madness 🙂.

Yes, they look more suitable for your kind of bike.

You could perhaps change the outer ring for a slighter bigger one, but it
may be worth having a lower top gear than you would ideally want in order to
have more suitable bottom and middle gears. This is what I've done on my
own bikes. It is no big deal to have to freewheel down steep hills. I make
do with a 50x14 top gear on my hack-tourer (with 700c wheel).

~PB

Pete Biggs said:

Tom Anderson said:

Quoted message said:

> You can use any combination of an N-speed crankset, M-speed cassette
> and P-speed chain as long as P >= N and P >= M?

P <=> N and P>= M

P <=> N?

And presumably N <=> M?

That would mean describing a crankset as '9-speed' meant nothing at
all.

It does mean almost nothing to completely nothing in practice. Welcome
to the clashing worlds of marketing and bike customisation. If there
are any dimensional differences between a chainset of one speed and
another, they will be small and usually of no noticeable consequence.

RAGE.

Quoted message said:

Even *brakes* are sometimes described as "9 speed"! As if they couldn't
be used with 8 or 10-speed systems! Actually it's just because they're
part of a 9-speed groupset and visually match the other components.

Oh, but that actually does make sense. Brakes have to be designed to stop
you at any of the speeds you can go, so if you have a 9-speed groupset,
you need a brake that works at more speeds than if you have an 8-speed
groupset.

Obviously.

tom

--
I had no idea it was going to end in such tragedy

Pete Biggs said:

Tom Anderson said:

Okay, this:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=69972&vertical=1&v=VARFCM410

This isn't far off either:

http://www.ultimatepursuits.co.uk/products/details.aspx?ref=14480&pRef=83706&vertical=1&v=VARFCM532

Both of those presumably fit a JIS square BB, and are in ideologically
pure 104/64 BCD, rather than any kind of overgrown road madness 🙂.

Yes, they look more suitable for your kind of bike.

You could perhaps change the outer ring for a slighter bigger one, but
it may be worth having a lower top gear than you would ideally want in
order to have more suitable bottom and middle gears.

Bear in mind that i currently have a top of 42. Even 48 will be a step up
in the world for me. Any number beginning with a 5 just seems unthinkable.

Quoted message said:

This is what I've done on my own bikes. It is no big deal to have to
freewheel down steep hills. I make do with a 50x14 top gear on my
hack-tourer (with 700c wheel).

This is also exactly what i'm planning - i want to maintain good
low-speed, poor surface, and hill capability, and i very rarely have a
chance to go >25 mph. Even 20 mph is a bit of a treat, actually.

tom

--
I had no idea it was going to end in such tragedy

Tom Anderson said:

Quoted message said:

Even *brakes* are sometimes described as "9 speed"! As if they
couldn't be used with 8 or 10-speed systems! Actually it's just
because they're part of a 9-speed groupset and visually match the
other components.

Oh, but that actually does make sense. Brakes have to be designed to
stop you at any of the speeds you can go, so if you have a 9-speed
groupset, you need a brake that works at more speeds than if you have
an 8-speed groupset.

Obviously.

Excellent. There will be jobs in $himaNO's and Crampandgoslow's marketing
departments waiting for you.

~PB