Changing the gearing on a crankset?

[Sean M. Cunningham]

Hello,

I'm trying to put together a road bike. It's my first attempt at building
a
bike from the frame up.

For gearing, I'm looking at using a 32-42-52T crankset, or something in
that area.

Right now, I have two cranksets. Both are geared for a mountain bike. One
is a Shimano Altus 24-34-42T; the other is a Shimano Hyperdrive-C. The
Hyperdrive is installed on my mountain bike right now, and it's covered
with grime, so I didn't want to touch it :) but it looks to be nearly the
same size as the Altus.

I was wondering if it's possible to take either of these apart, use the
large and middle sized chainrings, discard the small one, and add a big
52T ring. It doesn't look like they can be taken apart, but I haven't
tried prying/pulling/twisting anything, as I don't really know what to
look for, and I don't want to break or bend either of these.

Any advice you can give would be appreciated.

Thanks,


---
Sean Cunningham

[firm65]

"Sean M. Cunningham" > wrote in message
...
> Hello,
>
> I'm trying to put together a road bike. It's my first attempt at building
> a
> bike from the frame up.
>
> For gearing, I'm looking at using a 32-42-52T crankset, or something in
> that area.
>
> Right now, I have two cranksets. Both are geared for a mountain bike. One
> is a Shimano Altus 24-34-42T; the other is a Shimano Hyperdrive-C. The
> Hyperdrive is installed on my mountain bike right now, and it's covered
> with grime, so I didn't want to touch it :) but it looks to be nearly the
> same size as the Altus.
>
> I was wondering if it's possible to take either of these apart, use the
> large and middle sized chainrings, discard the small one, and add a big
> 52T ring. It doesn't look like they can be taken apart, but I haven't
> tried prying/pulling/twisting anything, as I don't really know what to
> look for, and I don't want to break or bend either of these.
>
> Any advice you can give would be appreciated.
>
> Thanks,
>
>
> ---
> Sean Cunningham
>
>Is the bottom bracket compatible? The bolt pattern of the crankset you
>would like to use ,probably is not . A typical road bolt pattern is
>130mm.You can get the old Dura Ace at a value right now.

[Sheldon Brown]

Sean M. Cunningham wrote:

> I'm trying to put together a road bike. It's my first attempt at building
> a bike from the frame up.
>
> For gearing, I'm looking at using a 32-42-52T crankset, or something in
> that area.
>
> Right now, I have two cranksets. Both are geared for a mountain bike. One
> is a Shimano Altus 24-34-42T; the other is a Shimano Hyperdrive-C. The
> Hyperdrive is installed on my mountain bike right now, and it's covered
> with grime, so I didn't want to touch it :) but it looks to be nearly the
> same size as the Altus.
>
> I was wondering if it's possible to take either of these apart, use the
> large and middle sized chainrings

This is not practical. Even if the chainrings are bolted instead of
rivetted (not sure about the models you have) they wouldn't fit on the
different positions of the crank.

I'd suggest looking at the $72.95 Sora or $87.95 Tiagra cranksets for
your application.

http://sheldonbrown.com/harris/cranks.html#13074

Sheldon "Sora" Brown
+----------------------------------------------------------+
| The people who live in a Golden Age usually go around |
| complaining how yellow everything looks. |
| -- Randall Jarrell |
+----------------------------------------------------------+
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

[Russell Seaton]

Also check Nashbar for the Shimano Sora triple crankset. $49.95.
52-42-30 chainrings. Not sure if it uses the square taper bottom
bracket or the Shimano Octalink.

http://www.nashbar.com/profile.cfm?category=81&subcategory=1034&brand=&sku=2950&storetype=&estoreid=&pagename=



"Sean M. Cunningham" > wrote in message >...
> Hello,
>
> I'm trying to put together a road bike. It's my first attempt at building
> a
> bike from the frame up.
>
> For gearing, I'm looking at using a 32-42-52T crankset, or something in
> that area.
>
> Right now, I have two cranksets. Both are geared for a mountain bike. One
> is a Shimano Altus 24-34-42T; the other is a Shimano Hyperdrive-C. The
> Hyperdrive is installed on my mountain bike right now, and it's covered
> with grime, so I didn't want to touch it :) but it looks to be nearly the
> same size as the Altus.
>
> I was wondering if it's possible to take either of these apart, use the
> large and middle sized chainrings, discard the small one, and add a big
> 52T ring. It doesn't look like they can be taken apart, but I haven't
> tried prying/pulling/twisting anything, as I don't really know what to
> look for, and I don't want to break or bend either of these.
>
> Any advice you can give would be appreciated.
>
> Thanks,
>
>
> ---
> Sean Cunningham
>

[Nate Knutson]

"Sean M. Cunningham" > wrote in message >...
> Hello,
>
> I'm trying to put together a road bike. It's my first attempt at building
> a
> bike from the frame up.
>
> For gearing, I'm looking at using a 32-42-52T crankset, or something in
> that area.
>
> Right now, I have two cranksets. Both are geared for a mountain bike. One
> is a Shimano Altus 24-34-42T; the other is a Shimano Hyperdrive-C. The
> Hyperdrive is installed on my mountain bike right now, and it's covered
> with grime, so I didn't want to touch it :) but it looks to be nearly the
> same size as the Altus.
>
> I was wondering if it's possible to take either of these apart, use the
> large and middle sized chainrings, discard the small one, and add a big
> 52T ring. It doesn't look like they can be taken apart, but I haven't
> tried prying/pulling/twisting anything, as I don't really know what to
> look for, and I don't want to break or bend either of these.
>
> Any advice you can give would be appreciated.
>
> Thanks,
>
>
> ---
> Sean Cunningham
>

Most cheap cranksets, probably including at least the Altus one you
have, have non-replaceable chainrings. Basically, if it doesn't have
obvious bolts that take allen wrenches, it's a crankset with
non-replaceable rings. The other crank you mentioned may or may not
have replaceable rings: Hyperglide C isn't a Shi product line, it's
one of their feature terms that some cranksets have stickers for. Some
of these cranks have replaceable rings and some don't. However, most
(maybe all, not sure) of the ones that do happened to use a bolt
circle diameter (the term for the diameter of the circle which passes
through all the chainring bolt holes on a crank) that road-size rings
don't exist for. So basically what you have won't work. You have some
options for what to get instead, as others have mentioned. I would
recommend making sure you avoid the pitfall of getting too high of a
gearing range - 52 is way too high for most people. 46, 48, or 50 is
usually a lot better. You have to be working really, really hard to
spin out a 50/11 or 50/12.