? How to Change MTB Rings/Cogs for Road Riding

I've got a Shimano drivetrain with the standard chainring set
(42/32/22) and a 7 speed cassette. In the flats, I ride in the big ring and small cog; however, on
descents I don't have a high enough gear ratio such that I can pedal to accelerate and
maintain speed.

Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur? Would
the derailleur work with the MTB shifter? I don't imagine that I can get cogs much smaller. Thanks
in advance for your help.

On 6 Aug 2003 08:06:37 -0700, HKEK <coolmale@hotmail.com> wrote:
> Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur? Would
> the derailleur work with the MTB

I think you'll find that you at least need a new derailleur. I don't know if it will work with
your shifter.

> shifter? I don't imagine that I can get cogs much smaller. Thanks in advance for your help.

My mountain bike has a 7-speed 11-34 cassette. I got it at my LBS. I think it's a Shimano, but it
may be a SRAM. It says "Mega-range" on it.

How small is your smallest?

--
Rick Onanian

"HKEK" <coolmale@hotmail.com> wrote in message
news:16063ad.0308060706.10546b33@posting.google.com...
> I've got a Shimano drivetrain with the standard chainring set
> (42/32/22) and a 7 speed cassette. In the flats, I ride in the big ring and small cog; however, on
> descents I don't have a high enough gear ratio such that I can pedal to accelerate and
> maintain speed.
>
> Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur? Would
> the derailleur work with the MTB shifter? I don't imagine that I can get cogs much smaller. Thanks
> in advance for your help.

You won't be able to put road rings on your crankset as they use a different bolt pattern (130 to
your 110). You can, however, get 110 rings that are larger than what you have. Perhaps a 46 tooth or
48 tooth would do the trick. A 48 would probably require a new deraileur but you can probably get
away with the 46. As suggested, a cassette with an 11 tooth small cog might help depending on what
you've got now.

Rob Strickland

"Robert Strickland" <robertstrickland@hotmail.com> wrote in message
news:bgr9p9$26o$03$1@news.t-online.com...
>
> "HKEK" <coolmale@hotmail.com> wrote in message
> news:16063ad.0308060706.10546b33@posting.google.com...
> > I've got a Shimano drivetrain with the standard chainring set
> > (42/32/22) and a 7 speed cassette. In the flats, I ride in the big ring and small cog; however,
> > on descents I don't have a high enough gear ratio such that I can pedal to accelerate
> > and maintain speed.
> >
> > Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur?
> > Would the derailleur work with the MTB shifter? I don't imagine that I can get cogs much
> > smaller. Thanks in advance for your help.
>
> You won't be able to put road rings on your crankset as they use a
different
> bolt pattern (130 to your 110). You can, however, get 110 rings that are larger than what you
> have. Perhaps a 46 tooth or 48 tooth would do the trick. A 48 would probably require a new
> deraileur but you can probably
get
> away with the 46. As suggested, a cassette with an 11 tooth small cog
might
> help depending on what you've got now.

Cambria has 46T chainrings in 94 and 110 size for 15 bucks. However, it might be a good idea to also
step up the middle chainring too, if the bike is ridden mainly on roads at higher speeds.

The front derailleur may have to be replaced, or at the very least, it will have to be moved up to
accommodate the larger chainring. How is the front derailleur mounted?

Unless you are careful shifting, you may need a longer chain. How old is the one you have now? Maybe
it's time for a new one anyway. The rear derailleur will probably be ok.

But I gotta ask why you're riding a mountain bike at, presumably, 18-20mph pace on the road? Do you
ever take it off trail? I hope you have slicks.

If the issue is money, or having just one bike, then it's a perfectly understandable situation. But
if you think you're going to be mostly riding on the road at these speeds, your long term plan ought
to be to get a different/additional bike.

John Rees

On 6 Aug 2003 08:06:37 -0700, coolmale@hotmail.com (HKEK) wrote:

>I've got a Shimano drivetrain with the standard chainring set
>(42/32/22) and a 7 speed cassette. In the flats, I ride in the big ring and small cog; however, on
> descents I don't have a high enough gear ratio such that I can pedal to accelerate and
> maintain speed.
>
>Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur? Would
>the derailleur work with the MTB shifter? I don't imagine that I can get cogs much smaller. Thanks
>in advance for your help.

If the smallest cog on your cassette is a 12 tooth then you can get one with an 11 tooth sprocket
for some improvement.

If you are already running a three chainrings with a MTB cassette then you probably already have a
long cage derailleur. If you get larger chainrings you will probably need to lengthen the chain.

Regarding the cranks, chainring replacement depends on the BCD (bolt-circle-diameter) of your
chainrings (see link). Cheap cranks are riveted together and the only way to change the chainrings
is to change the cranks. Recent Shimano cranks use one of two 4-bolt patterns and they don't offer
the chainrings with a decent range of sizes (perhaps some 3rd party offers them, I don't really know
- or care). If they are 5-bolt then they may be either 110/74 ("Standard") or 94/58 ("Compact), in
which case a wide range replacement chainrings are still widely available, no thanks to Shimano.

http://www.hostelshoppe.com/tech_bol...e_diameter.php

If you are going to get a new crank for the front the 110/74 is the best choice, very versatile both
on road and off.

--
Chris Bird

On Thu, 07 Aug 2003 07:49:56 GMT, Chris B. <csbird1@-nospam-thanks-rogers.com> wrote:

>If you are already running a three chainrings with a MTB cassette then you probably already have a
>long cage derailleur. If you get larger chainrings you will probably need to lengthen the chain.

Regarding the front derailleur, the one you have shifting your
22/32/42 setup will not be ideal if you move to something like
22/33/46 or 28/38/48 but it will shift just fine in my experience. However, a NOS (new, old stock)
front MTB derailleur for standard rings can usually be gotten used or from your LBS or Cambria
for a good price. A Shimano MTB front derailleur will shift fine with your shifters.

--
Chris Bird

robert-<< You won't be able to put road rings on your crankset as they use a different bolt pattern
(130 to your 110). You can, however, get 110 rings that are larger than what you have. Perhaps a 46
tooth or 48 tooth would do the trick. >><BR><BR>

TA makes 110/74 bolt diameter rings from 22(74mm) to 57mm(110)...so making a
52/42/30 would be easy.

May need an old style MTB front der desiogned for 46/48t rings tho-

Can also put a 'road' cassette on the rear...like an 11-23...

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(53)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

"Qui si parla Campagnolo" <vecchio51@aol.com> wrote in message
news:20030807093541.08111.00000318@mb-m06.aol.com...
> robert-<< You won't be able to put road rings on your crankset as they use
a
> different bolt pattern (130 to your 110). You can, however, get 110 rings that are larger than
> what you have. Perhaps a 46 tooth or 48 tooth would do the trick. >><BR><BR>
>
> TA makes 110/74 bolt diameter rings from 22(74mm) to 57mm(110)...so making
a
> 52/42/30 would be easy.
>
> May need an old style MTB front der desiogned for 46/48t rings tho-
>

Wouldn't an old RSX front der work? RSX bikes had 46t on a triple chainring.

On 6 Aug 2003 08:06:37 -0700, coolmale@hotmail.com (HKEK) wrote:

>I've got a Shimano drivetrain with the standard chainring set
>(42/32/22) and a 7 speed cassette. In the flats, I ride in the big ring and small cog; however, on
> descents I don't have a high enough gear ratio such that I can pedal to accelerate and
> maintain speed.
>
>Is it a simple matter to put road rings a MTB crankset? Would that require a new derailleur? Would
>the derailleur work with the MTB shifter? I don't imagine that I can get cogs much smaller. Thanks
>in advance for your help.

I had a similar set-up on my bike. I simply put on a 46T big-ring. The stock derailer worked
fine..one caveat..if you have an indesxed front shifter, you may have some difficulty with
this setup.

Bob

On Thu, 07 Aug 2003 07:49:56 GMT, Chris B. <csbird1@-nospam-thanks- rogers.com> wrote:
> If the smallest cog on your cassette is a 12 tooth then you can get one with an 11 tooth sprocket
> for some improvement.

You may also be able to replace just the 12 tooth cog, without replacing the whole cassette.

--
Rick Onanian