Chainring "upgrade" question

Borrall Wonnell said:

Hi folks,

I've got a 2002 hardtail that I'm using 80/20 commuting/offroad, with a
22/32/42T crankset.
I would like to improve my top speed by replacing the 42T chainring
with a larger one.

There are a couple of possibilities. You may have a 5-bolt, 94/58mm
crankset. In this case, there is no problem. 46 and even 48-tooth
chainrings are widely available. I use these cranks, road bike and
mountain, and have no problem getting rings from the big mail-order
places, or swap meets. The rings are typically quite cheap, too.

OTOH, you might have 4-bolt, 104mm cranks, a recent "innovation" by
Shimano that has now been widely copied. Problem here is that there is
much less of a choice for chainring sizes.

Quoted message said:

Can this be done without swapping out the crankset? Each chainring can
be individually removed, but I don't know if this is feasible for two
reasons:
1) Physically mounting a larger chainring (bolt pattern/location) 2)
Ability to shift between the middle and large chainring

On my road bike I use a 46/30. Shifting is not a problem. Shimano
shifting is a bit fussier on the front than Camapgnolo, which I use, so
you may have to be careful adjusting the derailleur. But it should work.
You might do well to get a chain watcher device, just to be on the safe
side.

Quoted message said:

On another note, a couple of weeks ago I noticed that my middle
chainring is slightly bent on one side. I'm a bit astounded that this
kind of damage is even possible without bending the other rings.

Probably a chain-suck episode, where the chain got jammed between the
chainrings.

--

David L. Johnson

__o | The motor car reflects our standard of living and gauges the
_`\(,_ | speed of our present life. It long ago ran down Simple Living,
(_)/ (_) | and never halted to inquire about the prostrate figure which
fell as its victim. -- Warren G. Harding

Quoted message said:

OTOH, you might have 4-bolt, 104mm cranks, a recent "innovation" by
Shimano that has now been widely copied. Problem here is that there is
much less of a choice for chainring sizes.

Thanks for the info. My cranks are a 4-bolt design, and are made by
Shimano. I'll assume they're 104/64 mm spacing (is there any other
4-bolt spacing in recent years?)

I have found some 44-48T chainrings to fit a 104mm pattern. The XT
front derailleur indicates a maximum spread (big - small ring) of 22T,
so unless I replace all the rings the largest I can go (and still be
convinced it will work) is a 44T.

Are the majority of recent Shimano MTB cranks 4-bolt?

"Borrall Wonnell" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

OTOH, you might have 4-bolt, 104mm cranks, a recent "innovation" by
Shimano that has now been widely copied. Problem here is that there is
much less of a choice for chainring sizes.

Thanks for the info. My cranks are a 4-bolt design, and are made by
Shimano. I'll assume they're 104/64 mm spacing (is there any other
4-bolt spacing in recent years?)

I have found some 44-48T chainrings to fit a 104mm pattern. The XT
front derailleur indicates a maximum spread (big - small ring) of 22T,
so unless I replace all the rings the largest I can go (and still be
convinced it will work) is a 44T.

Are the majority of recent Shimano MTB cranks 4-bolt?

If you've got a bent middle and small upper - may as well replace the lot!
I use a 24-38-48 for touring with XT
Just about perfect for me.
Peter

Borrall Wonnell says...

Quoted message said:

Hi folks,

I've got a 2002 hardtail that I'm using 80/20 commuting/offroad, with a
22/32/42T crankset.
I would like to improve my top speed by replacing the 42T chainring
with a larger one.

Can this be done without swapping out the crankset? Each chainring can
be individually removed, but I don't know if this is feasible for two
reasons:
1) Physically mounting a larger chainring (bolt pattern/location)
2) Ability to shift between the middle and large chainring

On another note, a couple of weeks ago I noticed that my middle
chainring is slightly bent on one side. I'm a bit astounded that this
kind of damage is even possible without bending the other rings.

I really don't want to sound sarcastic, but how fast can you go on a
MTB? A 42/12 will give you about 24 mph at a 90 rpm cadence, and that
is not particularly fast pedalling. If you can sustain that for any
length of time, you are doing very well. Still, if you really want a
bigger gear, anything bigger than a 44 will be special order.
Cambriabike had a Salsa 48 last I checked in 104 bcd, which appears to
be what you have. 46 is somewhat more common. You can probably use
your current derailleur with some judicious adjusting, but it may not
work quite as well if you have bigger jumps.

Barnard Frederick said:

Borrall Wonnell says...

Quoted message said:

Hi folks,

I've got a 2002 hardtail that I'm using 80/20 commuting/offroad, with a
22/32/42T crankset.
I would like to improve my top speed by replacing the 42T chainring
with a larger one.

Can this be done without swapping out the crankset? Each chainring can
be individually removed, but I don't know if this is feasible for two
reasons:
1) Physically mounting a larger chainring (bolt pattern/location) 2)
Ability to shift between the middle and large chainring

On another note, a couple of weeks ago I noticed that my middle
chainring is slightly bent on one side. I'm a bit astounded that this
kind of damage is even possible without bending the other rings.

I really don't want to sound sarcastic, but how fast can you go on a
MTB? A 42/12 will give you about 24 mph at a 90 rpm cadence, and that
is not particularly fast pedalling. If you can sustain that for any
length of time, you are doing very well. Still, if you really want a
bigger gear, anything bigger than a 44 will be special order.
Cambriabike had a Salsa 48 last I checked in 104 bcd, which appears to
be what you have. 46 is somewhat more common. You can probably use
your current derailleur with some judicious adjusting, but it may not
work quite as well if you have bigger jumps.

Well I guess I can go pretty fast then, especially downhill. I have a
42/11 on my MTB and I find it inadequate for the road, and even off road
at times. I like to be able to pedal comfortably to about 30 MPH. There
are plenty of long, not so steep downhills around here that I'd like to
take advantage of. For me, a 46/11 top gear would be about right. In
fact a 24-34-46 crank with a 9sp 11-32 cassette, like standard XTR, is
about perfect.

To answer the original question, you can get 44, 46, and 48T chainrings
for 58/94 cranks, or whatever. There are plenty of aftermarket chainring
suppliers making them. Watch the lateral spacing though, which can be a
real pain. When all chainrings were flat it was hardly an issue, but
these days with 3D chainrings they're all different. You might mention
which model crank you have so someone can suggest a "known good"
combination.

Matt O.

Borrall Wonnell said:

I have found some 44-48T chainrings to fit a 104mm pattern. The XT
front derailleur indicates a maximum spread (big - small ring) of 22T,
so unless I replace all the rings the largest I can go (and still be
convinced it will work) is a 44T.

These capacities are often very conservative. I would not worry about a
46, certainly. A 48 should also work with your current middle ring.

Quoted message said:

Are the majority of recent Shimano MTB cranks 4-bolt?

Depends on your definition of "recent", but yeah, all of them.

--

David L. Johnson

__o | "What am I on? I'm on my bike, six hours a day, busting my ass.
_`\(,_ | What are you on?" --Lance Armstrong
(_)/ (_) |

Matt O'Toole says...

Quoted message said:

Well I guess I can go pretty fast then, especially downhill. I have a
42/11 on my MTB and I find it inadequate for the road, and even off road
at times. I like to be able to pedal comfortably to about 30 MPH. There
are plenty of long, not so steep downhills around here that I'd like to
take advantage of. For me, a 46/11 top gear would be about right. In
fact a 24-34-46 crank with a 9sp 11-32 cassette, like standard XTR, is
about perfect.

Of course you know that the value (or lack thereof) of pedalling
downhill has been hotly debated here. But if you are on a really fast
hill, you won't be able to pedal no matter what your gearing. If a gear
is too tall for level ground with a good tailwind, it's just a luxury.

Thanks for the comments everyone. I really appreciate them.

As for the gearing, I currently run an 11-34 9 speed cassette. I am
not interested in a larger chainring for steep downhills...normally I'm
just holding on for dear life in these situations!

I wouldn't consider an upgrade to 44-46-48T a 'luxury' gear. On
relatively flat (slight downhill grade) roads I am in top gear (42-11)
almost immediately. I am finding that I am spinning at a somewhat
uncomfortable (MTB) 110+ RPM with plenty of power to spare. If I
switch to slicks, it gets even worse.

I like the idea of a 24-34-46 crank. Is such a beast available in
104/64 (4-bolt), or is it only available in 5-bolt patterns? I'll go
check on the current XTR specs to verify for myself. If I upgrade all
of my rings to larger sizes I would expect that the front derailleur to
be much more forgiving than if I went 22-32-48.

If I can find 24-34-46 rings in 104/64, should I simply bolt 'em on to
my existing crank? Should I replace my cranks (low end Shimano MC-20)?
If so, should I also replace my BB?

Thanks again,
Dave

Borrall Wonnell said:

I like the idea of a 24-34-46 crank. Is such a beast available in
104/64 (4-bolt), or is it only available in 5-bolt patterns? I'll go
check on the current XTR specs to verify for myself. If I upgrade all
of my rings to larger sizes I would expect that the front derailleur to
be much more forgiving than if I went 22-32-48.

If I can find 24-34-46 rings in 104/64, should I simply bolt 'em on to
my existing crank? Should I replace my cranks (low end Shimano MC-20)?
If so, should I also replace my BB?

http://tinyurl.com/hvgfz

Borrall Wonnell says...

Quoted message said:

I like the idea of a 24-34-46 crank. Is such a beast available in
104/64 (4-bolt), or is it only available in 5-bolt patterns? I'll go
check on the current XTR specs to verify for myself. If I upgrade all
of my rings to larger sizes I would expect that the front derailleur to
be much more forgiving than if I went 22-32-48.

If I can find 24-34-46 rings in 104/64, should I simply bolt 'em on to
my existing crank? Should I replace my cranks (low end Shimano MC-20)?
If so, should I also replace my BB?

Thanks again,
Dave

You could upgrade all your rings if you want, but the big one is the
only one you really need. If you get the correct bolt pattern, you
should be able to use an after market ring, but I seem to remember
hearing of occasional problems. Can't say any more than that, since I
haven't tried it for myself. Anything larger than a 44 will be hard to
find with a new crankset. There may be some out there, but I haven't
seen them. Maybe someone could post a link? The gearing you want is
common to cyclocross bikes, but don't get a cyclocross crankset, because
it probably won't clear your chainstays.

In article
<[email hidden]>,

Borrall Wonnell said:

Thanks for the comments everyone. I really appreciate them.

As for the gearing, I currently run an 11-34 9 speed cassette. I am
not interested in a larger chainring for steep downhills...normally I'm
just holding on for dear life in these situations!

I wouldn't consider an upgrade to 44-46-48T a 'luxury' gear. On
relatively flat (slight downhill grade) roads I am in top gear (42-11)
almost immediately. I am finding that I am spinning at a somewhat
uncomfortable (MTB) 110+ RPM with plenty of power to spare. If I
switch to slicks, it gets even worse.

I like the idea of a 24-34-46 crank. Is such a beast available in
104/64 (4-bolt), or is it only available in 5-bolt patterns? I'll go
check on the current XTR specs to verify for myself. If I upgrade all
of my rings to larger sizes I would expect that the front derailleur to
be much more forgiving than if I went 22-32-48.

If I can find 24-34-46 rings in 104/64, should I simply bolt 'em on to
my existing crank? Should I replace my cranks (low end Shimano MC-20)?
If so, should I also replace my BB?

First consider the change from 42/11 to 46/11.
At 90 rpm the (for a 700c wheel) the speed goes from 43.5
to 47.5 kph. Is this increase enough to justify the work?

--
Michael Press

Quoted message said:

First consider the change from 42/11 to 46/11.
At 90 rpm the (for a 700c wheel) the speed goes from 43.5
to 47.5 kph. Is this increase enough to justify the work?

We'll see. I've got a 26-36-48 on the way. It should buy me an extra 5
MPH at the top end. Not a lot of speed, but helpful to maintain
traffic flow. In terms of work, if I'm lucky it will just be a matter
of swapping crankarms and adjusting the front derailleur. Now that
I've done this a few times (over the last week or so), shouldn't be a
problem. Hopefully, the rings will clear the chainstay and won't
require a longer BB spindle. The front der *should* handle the larger
rings ok (according to spec)....but we'll see.

Borrall Wonnell said:

Hi folks,

I've got a 2002 hardtail that I'm using 80/20 commuting/offroad, with a
22/32/42T crankset.
I would like to improve my top speed by replacing the 42T chainring
with a larger one.

Can this be done without swapping out the crankset? Each chainring can
be individually removed, but I don't know if this is feasible for two
reasons:
1) Physically mounting a larger chainring (bolt pattern/location)
2) Ability to shift between the middle and large chainring

On another note, a couple of weeks ago I noticed that my middle
chainring is slightly bent on one side. I'm a bit astounded that this
kind of damage is even possible without bending the other rings.

Cheers,
Dave

Probably as long as the chainring bolt diameter isn't some sort of
unique size to that crank diameter. Adding a bigger ring w/i reason w/o
changing the others will work to a point. If it's too large, you will
have to raise the FD so high, the FD won't work with the small ring. Up
to about 46t would probably work. See a bike shop that either has or
can get a variety of CRs...

http://www.thethirdhand.com/ has rings
harris cyclery with sheldon brown has info on measuring

nashbar recently offered the following at 48 teeth

Nashbar ISIS Trekking Crankset 48/38/28

Truvativ Elita Cyclocross Crankset - 48/39

this is reasonable - the 53 is more of a road racer number not a fast
commmuter tooth number as in given the number of opportunities to use
53 or 48 with a 14 and higher rear or the using the middle cassette
cogs, the 48 probabbbly gives more chances than the 53 or 52

3 teeth more or less iza lotta teeth regaurdless of the mph numbers.

i bought a 40 to replace a bottom 43 of the classic 43/52 for the
specific purpose of pedaling a touring load into the onshore 15 mph
breeze and the 40 works very well for this purpose. i wanna a 41.

however, 3 teeth from the classsic 43 gives a two part gearbox, one low
one hi.
the seamless downshift from 53 to 43 is gone. instead, i get a seamless
pillow of no speed. i broke up and fell off the bike at 15 mph on the
first try -like i shifted and pedaled but nothing happened but a 9 mph
loss of speed.

notice that nbar dropped the 52/53 to 48

one can also view the shift to 48 in terms of obesity and sloth but
we're not into obesity and sloth are we?

a chain ring bolt tool can be made from a 1.08 walmort needlenose
pliers (and grok the hex key sets) by filing the noses down to fit then
holding the nose spacing with the walmort $2 vice grips after inserting
into the bolt grooves - use red loctite