Any issues fitting a road triple on a commuter mountain bike?

[damyth]

A friend of mine has a mountain bike with slicks that he uses as a
commuter. The commute is relatively flat, about 30mi round trip. He
currently has a 42/32/22 crankset, and he uses only the 11 and 12t
(mostly 11t). As a result, he uses up cassettes virtually every 2-3
months or so, such that a new replacement chain skips on those two
cogs.

Is there a cheap source for 11t and 12t Shimano cogs, such that
replacement cost of 2 cogs doesn't approach the cost of replacing the
whole cassette (about $25 at Performance, house brand)? I think
ideally I'd like to put on a road triple (52/42/30) so at least he
would be on the 14t (same ratio) on the large chainring. Is there any
down side or peculiarities to putting a road triple on a mountain bike?
Chainline, BB spindle weirdness, or maybe even front derailleur?

His current BB is square taper, and he never goes off road with this
bike. And he does practice good chain hygiene, pretty diligent about
soaking chain in kerosene as soon as he sees dirt on them. I'm
thinking the Sugino XD500 should be pretty good cranksets for him.

 

[Ryan Cousineau]

In article <[email protected]>,
"damyth" <[email protected]> wrote:

> A friend of mine has a mountain bike with slicks that he uses as a
> commuter. The commute is relatively flat, about 30mi round trip. He
> currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> months or so, such that a new replacement chain skips on those two
> cogs.
>
> Is there a cheap source for 11t and 12t Shimano cogs, such that
> replacement cost of 2 cogs doesn't approach the cost of replacing the
> whole cassette (about $25 at Performance, house brand)? I think
> ideally I'd like to put on a road triple (52/42/30) so at least he
> would be on the 14t (same ratio) on the large chainring. Is there any
> down side or peculiarities to putting a road triple on a mountain bike?
> Chainline, BB spindle weirdness, or maybe even front derailleur?
>
> His current BB is square taper, and he never goes off road with this
> bike. And he does practice good chain hygiene, pretty diligent about
> soaking chain in kerosene as soon as he sees dirt on them. I'm
> thinking the Sugino XD500 should be pretty good cranksets for him.

For best shifting, change front derailer with the front rings. Because
this is a road setup with a flat bar, you'll need the magic Shimano R443
derailer. I'm assuming this is an indexed drivetrain. If by some magic
he has friction shifters on this bike, then any old road derailer
designed for a 52 front will do.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

 

[Mark Hickey]

"damyth" <[email protected]> wrote:

>A friend of mine has a mountain bike with slicks that he uses as a
>commuter. The commute is relatively flat, about 30mi round trip. He
>currently has a 42/32/22 crankset, and he uses only the 11 and 12t
>(mostly 11t). As a result, he uses up cassettes virtually every 2-3
>months or so, such that a new replacement chain skips on those two
>cogs.
>
>Is there a cheap source for 11t and 12t Shimano cogs, such that
>replacement cost of 2 cogs doesn't approach the cost of replacing the
>whole cassette (about $25 at Performance, house brand)? I think
>ideally I'd like to put on a road triple (52/42/30) so at least he
>would be on the 14t (same ratio) on the large chainring. Is there any
>down side or peculiarities to putting a road triple on a mountain bike?
> Chainline, BB spindle weirdness, or maybe even front derailleur?

Ryan did a good job explaining the front derailleur issues... the only
other thing to consider is whether or not the larger rings will clear
the chainstay.

But in the end, the best answer is to teach your buddy to spin so he
can use more than just the 11t cog. ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

 

[Drew Saunders]

In article <[email protected]>,
"damyth" <[email protected]> wrote:

> A friend of mine has a mountain bike with slicks that he uses as a
> commuter. The commute is relatively flat, about 30mi round trip. He
> currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> months or so, such that a new replacement chain skips on those two
> cogs.
>
> Is there a cheap source for 11t and 12t Shimano cogs, such that
> replacement cost of 2 cogs doesn't approach the cost of replacing the
> whole cassette (about $25 at Performance, house brand)? I think
> ideally I'd like to put on a road triple (52/42/30) so at least he
> would be on the 14t (same ratio) on the large chainring. Is there any
> down side or peculiarities to putting a road triple on a mountain bike?
> Chainline, BB spindle weirdness, or maybe even front derailleur?
>
> His current BB is square taper, and he never goes off road with this
> bike. And he does practice good chain hygiene, pretty diligent about
> soaking chain in kerosene as soon as he sees dirt on them. I'm
> thinking the Sugino XD500 should be pretty good cranksets for him.

Why bother with a front derailleur? A quick poke about the web shows
104mm bcd 4-bolt chainrings (my guess as to what his crank uses) up to
48T, maybe larger. Just swap the big ring for a bigger one, and make it
a single-chainring setup. Ideally, you'd change the BB spindle for a
shorter one for optimal chainline, or you could put the single chainring
in the middle position and have it look funny, but it would work just
fine.

You could go with a road double too. Nashbar sells their house brand for
$45 with a 39x53. You'd want a new front derailleur too, or just not use
the inner ring.

Drew

--
Drew W. Saunders

dru (at) stanford (dot) eee dee you

 

[Ben C]

On 2006-10-20, Drew Saunders <[email protected]> wrote:
> In article <[email protected]>,
> "damyth" <[email protected]> wrote:
[snip]
> You could go with a road double too. Nashbar sells their house brand for
> $45 with a 39x53. You'd want a new front derailleur too, or just not use
> the inner ring.

I went without a front derailleur for a while but the chain tended to
fall off quite easily, especially from the big ring.

Don't know why exactly, I think probably because of poor chainline. It
was much better in the middle ring.

For a short time I also had no rear derailleur, with the chain shortened
appropriately to run on some reasonable choice of gear. This was middle
ring and one of the smaller cogs at the back. So the chain wanted to
pull itself straight, into a larger rear cog, which to my surprise
actually happened as soon as you pedalled even moderately hard, even
though the chain was too short to fit properly around the bigger cog and
seized as soon as it got there.

The forces pulling the chain into a straight chainline are much larger
than I'd realized. To run within a cog or twos' width of a perfect
chainline requires a rear derailleur to keep things together, and I
suspect that for larger deviations from perfect you need a front
derailleur too. Of course the front derailleur doesn't apply a
continuous force to the chain the way the rear does, but it may just
stop it coming off now and again, when you go over a bump etc., without
you realizing.

 

[damyth]

Drew Saunders wrote:
> In article <[email protected]>,
> "damyth" <[email protected]> wrote:
>
> > A friend of mine has a mountain bike with slicks that he uses as a
> > commuter. The commute is relatively flat, about 30mi round trip. He
> > currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> > (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> > months or so, such that a new replacement chain skips on those two
> > cogs.
> >
> > Is there a cheap source for 11t and 12t Shimano cogs, such that
> > replacement cost of 2 cogs doesn't approach the cost of replacing the
> > whole cassette (about $25 at Performance, house brand)? I think
> > ideally I'd like to put on a road triple (52/42/30) so at least he
> > would be on the 14t (same ratio) on the large chainring. Is there any
> > down side or peculiarities to putting a road triple on a mountain bike?
> > Chainline, BB spindle weirdness, or maybe even front derailleur?
> >
> > His current BB is square taper, and he never goes off road with this
> > bike. And he does practice good chain hygiene, pretty diligent about
> > soaking chain in kerosene as soon as he sees dirt on them. I'm
> > thinking the Sugino XD500 should be pretty good cranksets for him.
>
> Why bother with a front derailleur? A quick poke about the web shows
> 104mm bcd 4-bolt chainrings (my guess as to what his crank uses) up to
> 48T, maybe larger. Just swap the big ring for a bigger one, and make it
> a single-chainring setup. Ideally, you'd change the BB spindle for a
> shorter one for optimal chainline, or you could put the single chainring
> in the middle position and have it look funny, but it would work just
> fine.
>
> You could go with a road double too. Nashbar sells their house brand for
> $45 with a 39x53. You'd want a new front derailleur too, or just not use
> the inner ring.
>
> Drew
>
> --
> Drew W. Saunders
>
> dru (at) stanford (dot) eee dee you

Yes, this did occur to me, but apparently chainrings >48t are extremely
hard to come by for his 5 arm 110bcd crank. He'd pretty much NEED a
52t chainring to move to a larger cog like 14t (which to me still isn't
sufficiently "large"). Otherwise he'd still be chewing up small cogs
for breakfast.

A road double (instead of a triple) might just be the ticket. Thanks
for the pointer for the Nashbar crank.

 

[* * Chas]

"damyth" <[email protected]> wrote in message
news:[email protected]...
> A friend of mine has a mountain bike with slicks that he uses as a
> commuter. The commute is relatively flat, about 30mi round trip. He
> currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> months or so, such that a new replacement chain skips on those two
> cogs.
>
> Is there a cheap source for 11t and 12t Shimano cogs, such that
> replacement cost of 2 cogs doesn't approach the cost of replacing the
> whole cassette (about $25 at Performance, house brand)? I think
> ideally I'd like to put on a road triple (52/42/30) so at least he
> would be on the 14t (same ratio) on the large chainring. Is there any
> down side or peculiarities to putting a road triple on a mountain
bike?
> Chainline, BB spindle weirdness, or maybe even front derailleur?
>
> His current BB is square taper, and he never goes off road with this
> bike. And he does practice good chain hygiene, pretty diligent about
> soaking chain in kerosene as soon as he sees dirt on them. I'm
> thinking the Sugino XD500 should be pretty good cranksets for him.
>

The least expensive way to go is to get some larger chainrings for your
friend's existing cranks. What brand of crankset does he have? What size
BCD (bolt center diameter) does he have?

There are a number of after market chainring manufacturers that make a
wide number of different chainrings.

Here's a site with info on TA chainrings. I've found other brands that
are a lot less money:

http://www.peterwhitecycles.com/chainrings.asp

Sheldon has some good info also:

http://sheldonbrown.com/harris/chainrings.html

I'd been running an old TA Cyclotouriste Double 42/26 on my mountain
bike for years. I used a 42/13 combo for on the road and hard pack but
it was never quite high enough. Also, the chain frequently hung on the
42 tooth chainring.

I recently installed an NOS Shimano Deore XT 48/38/28 crankset. I ended
up having to go from a 122mm BB to a 118mm BB and the change front
derailleur.

48/13 is plenty high for me. I find that most of the time I ride 70" to
85" gearing on the road. With 26" tires, 42/11 is 95.45 and 42/12 is
87.50. As someone else mentioned, you might suggest to you friend that
he run lower gears and increase his cadence.

Chas.

 

[Paul Kopit]

On 20 Oct 2006 14:12:13 -0700, "damyth"
<[email protected]> wrote:

>Yes, this did occur to me, but apparently chainrings >48t are extremely
>hard to come by for his 5 arm 110bcd crank. He'd pretty much NEED a
>52t chainring to move to a larger cog like 14t (which to me still isn't
>sufficiently "large"). Otherwise he'd still be chewing up small cogs
>for breakfast

I have several 50s, 52, and 54 in 110 bolt pattern. I also have some
36t rings to go with a 52.

 

[Sheldon Brown]

Someone wrote:
> A friend of mine has a mountain bike with slicks that he uses as a
> commuter. The commute is relatively flat, about 30mi round trip. He
> currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> months or so, such that a new replacement chain skips on those two
> cogs.
>
> I think
> ideally I'd like to put on a road triple (52/42/30) so at least he
> would be on the 14t (same ratio) on the large chainring. Is there any
> down side or peculiarities to putting a road triple on a mountain bike?
> Chainline, BB spindle weirdness, or maybe even front derailleur?

>From what you say about the riding style/conditions, I don't see why he
would need a triple of any sort. Why not go with a double, or even a
single chainring?

There are serious indexing difficulties with installing a "road" triple
on a mountain bike, but these problems don't arise with a double,
'cause doubles are way less fussy about indexing.

There are likely to be chainline issues, so he will likely need a
longer than usual BB spindle to keep the larger rings from hitting the
MTB's right chainstay.

Actually, it sounds to me as if he would be better off considering a
more suitable bike, this doesn't sound like a good application for a
mountain bike..

> His current BB is square taper,

Generally speaking, crank sets are MUCH more expensive than bottom
brackets.

As a result, when you're in the market for a crank set, it is generally
a mistake to put too much importance on matching your present bottom
bracket...this limits your choices unreasonably.

Sort of like choosing a new car because it will fit your existing snow
tires...

>and he never goes off road with this
> bike. And he does practice good chain hygiene, pretty diligent about
> soaking chain in kerosene as soon as he sees dirt on them.

This isn't necessarily the best way to go. See:
http://sheldonbrown.com/chains

See also: http://sheldonbrown.com/fixed

Sheldon "Commuters Are The Most 'Serious' Cyclists" Brown
+--------------------------------------------+
| To see what is in front of one's nose |
| needs a constant struggle |
| --George Orwell |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[* * Chas]

"Sheldon Brown" <[email protected]> wrote in message
news:[email protected]...
<snip>

> Sort of like choosing a new car because it will fit your existing snow
> tires...

What are snow tires? ;-)

 

[damyth]

Sheldon Brown wrote:
> Someone wrote:
> > A friend of mine has a mountain bike with slicks that he uses as a
> > commuter. The commute is relatively flat, about 30mi round trip. He
> > currently has a 42/32/22 crankset, and he uses only the 11 and 12t
> > (mostly 11t). As a result, he uses up cassettes virtually every 2-3
> > months or so, such that a new replacement chain skips on those two
> > cogs.
> >
> > I think
> > ideally I'd like to put on a road triple (52/42/30) so at least he
> > would be on the 14t (same ratio) on the large chainring. Is there any
> > down side or peculiarities to putting a road triple on a mountain bike?
> > Chainline, BB spindle weirdness, or maybe even front derailleur?
>
> >From what you say about the riding style/conditions, I don't see why he
> would need a triple of any sort. Why not go with a double, or even a
> single chainring?
>
> There are serious indexing difficulties with installing a "road" triple
> on a mountain bike, but these problems don't arise with a double,
> 'cause doubles are way less fussy about indexing.
>
> There are likely to be chainline issues, so he will likely need a
> longer than usual BB spindle to keep the larger rings from hitting the
> MTB's right chainstay.
>
> Actually, it sounds to me as if he would be better off considering a
> more suitable bike, this doesn't sound like a good application for a
> mountain bike..
>
> > His current BB is square taper,
>
> Generally speaking, crank sets are MUCH more expensive than bottom
> brackets.
>
> As a result, when you're in the market for a crank set, it is generally
> a mistake to put too much importance on matching your present bottom
> bracket...this limits your choices unreasonably.
>
> Sort of like choosing a new car because it will fit your existing snow
> tires...
>
> >and he never goes off road with this
> > bike. And he does practice good chain hygiene, pretty diligent about
> > soaking chain in kerosene as soon as he sees dirt on them.
>
> This isn't necessarily the best way to go. See:
> http://sheldonbrown.com/chains
>
> See also: http://sheldonbrown.com/fixed
>
> Sheldon "Commuters Are The Most 'Serious' Cyclists" Brown
> +--------------------------------------------+
> | To see what is in front of one's nose |
> | needs a constant struggle |
> | --George Orwell |
> +--------------------------------------------+
> Harris Cyclery, West Newton, Massachusetts
> Phone 617-244-9772 FAX 617-244-1041
> http://harriscyclery.com
> Hard-to-find parts shipped Worldwide
> http://captainbike.com http://sheldonbrown.com

Sheldon,

Regarding getting a different bike, I couldn't agree with you more.
The reason my friend got a mountain bike was the "perceived"
versatility, the "go anywhere" bike (even though I think this guy has
only gone off road a grand total of 3 times, while he rides the bike on
paved roads every weekday, and he definitely prefers the upright
position on a mountain bike (w/ the shorter top tube).

Needless to say, this friend would like to do this on the cheap. I
still have no been able to successfully convince him the costs of
replacing the drivetrain. I think his "new" strategy is to ride till
the (same) chain and cogs are completely unusable, and then go through
a chain/cassette upgrade.

If it were up to me I'd get him a cyclocross bike and retrofit it with
a flat bar. I don't think given his philosophy, he'd use a fixed gear
. But I really don't think this guy is going to give up this mountain
bike anytime soon, unless I can come up with some really compelling
reasons. The Nashbar double road crank that someone posted earlier is
starting to sound mighty attractive.