Yes, my math skiills suck

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

Quoted message said:

So, how do you determine, at a given gear combo, what speed will pedaling
have no affect.

How fast can you spin?

http://sheldonbrown.com/gain.html

Quoted message said:

I'm trying to figure out if I want to run a double or triple upfront.

Triple.

Greg

Slack said:

So, how do you determine, at a given gear combo, what speed will pedaling
have no affect.

I'm trying to figure out if I want to run a double or triple upfront.

You're worrying about the wrong end of the speed range (if I'm reading
your question correctly). Pedaling only loses its influence over the
speed of the bike when you're going down a STEEP hill. The difference
between the biggest and smallest big rings up front isn't likely to
make any difference in velocity down a hill that's steep enough to
spin out a 48-whatever combination.

That said, there's very little reason NOT to go with a triple. The
weight you add to the crank can be offset by the much smaller, lighter
cassette you can run (and still get the same gearing as a double crank
with a wide-range cassette). In addition, you end up having smaller
gaps between gears, which is a nice bonus.

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

Slack said:

So, how do you determine, at a given gear combo, what speed will pedaling
have no affect.

I'm trying to figure out if I want to run a double or triple upfront.
--
Slack

Is this for a CX bike? These comments are based on something I think
you mentioned last week about considering going from 2 to 3
chainrings.

1. I think you'll need a new, long rear derr too if you go from double
to triple, no?
2. I'm even less sure of this, but can you use the same Shimano
brifter with both 2 and 3 chainrings? I think if you were going from 3
to 2, you could manage it with the limit shops. I _think_ I've read
that a 9sp Ultegra shifter will work with 2 AND 3, but I could be
wrong.
3. The longer rear derr might lead to more chain slapping around.

/s

Slack said:

I'm trying to figure out if I want to run a double or triple upfront.

You? A triple.

JD

Mark Hickey said:

Slack said:

So, how do you determine, at a given gear combo, what speed will
pedaling
have no affect.

I'm trying to figure out if I want to run a double or triple upfront.

You're worrying about the wrong end of the speed range (if I'm reading
your question correctly). Pedaling only loses its influence over the
speed of the bike when you're going down a STEEP hill. The difference
between the biggest and smallest big rings up front isn't likely to
make any difference in velocity down a hill that's steep enough to
spin out a 48-whatever combination.

That said, there's very little reason NOT to go with a triple. The
weight you add to the crank can be offset by the much smaller, lighter
cassette you can run (and still get the same gearing as a double crank
with a wide-range cassette). In addition, you end up having smaller
gaps between gears, which is a nice bonus.

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

I have a bad habit of not fully explaining my intensions, so let me
elaborate.

The new, and better, xc bike I'm currently building is going to have
6"+ front and 6" in the back.
Now running it downhill on rocky/washboard terrain (doesn't have to be
steep) at speed is going to make
my chain bounce like crazy. So many bikes in this travel range are coming
with a chain-guide
like http://www.e13components.com/product_drs.html And it has the added
benefit of providing
a little protection for BB/lower shock mount on my frame since mine didn't
come with a lower
shock mount protector as shown here
http://www.mcconveycycles.com/smsimg/9/m3777_frame-reign.jpg
Although, I'm trying to locate one now.

But, and it's a big but, if removing the large ring upfront means I'm
almost never going to be able to pedal dh,
that is going to truly suck! I'm not sure it's worth the sacrifice..
--
Slack

JD said:

Slack said:

I'm trying to figure out if I want to run a double or triple upfront.

You? A triple.

JD

Yes, get it straight; triple chain-ring; double chin.
--
Slack - sponsored by In-&-Out

Slack said:

The new, and better, xc bike I'm currently building is going to have
6"+ front and 6" in the back.
Now running it downhill on rocky/washboard terrain (doesn't have to be
steep) at speed is going to make
my chain bounce like crazy. So many bikes in this travel range are coming
with a chain-guide
like http://www.e13components.com/product_drs.html And it has the added
benefit of providing
a little protection for BB/lower shock mount on my frame since mine didn't
come with a lower
shock mount protector as shown here
http://www.mcconveycycles.com/smsimg/9/m3777_frame-reign.jpg
Although, I'm trying to locate one now.

But, and it's a big but, if removing the large ring upfront means I'm
almost never going to be able to pedal dh,
that is going to truly suck! I'm not sure it's worth the sacrifice..

I think this is a good example of something (potentially) evolving
into something less viable... The big ring would seem to provide as
much protection as that plastic ring could (lots of riders out here in
AZ have some pretty rough-looking big rings as a result, due to all
the predatory boulders on the trails). ;-)

A DH bike that can't go fast down hills seems like a waste of
components. There are other ways to keep the chain on the bike
without having to give up the top half of your gearing!

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

Mark Hickey said:

Slack said:

The new, and better, xc bike I'm currently building is going to have
6"+ front and 6" in the back.
Now running it downhill on rocky/washboard terrain (doesn't have to be
steep) at speed is going to make
my chain bounce like crazy. So many bikes in this travel range are
coming
with a chain-guide
like http://www.e13components.com/product_drs.html And it has the added
benefit of providing
a little protection for BB/lower shock mount on my frame since mine
didn't
come with a lower
shock mount protector as shown here
http://www.mcconveycycles.com/smsimg/9/m3777_frame-reign.jpg
Although, I'm trying to locate one now.

But, and it's a big but, if removing the large ring upfront means I'm
almost never going to be able to pedal dh,
that is going to truly suck! I'm not sure it's worth the sacrifice..

I think this is a good example of something (potentially) evolving
into something less viable... The big ring would seem to provide as
much protection as that plastic ring could (lots of riders out here in
AZ have some pretty rough-looking big rings as a result, due to all
the predatory boulders on the trails). ;-)

A DH bike that can't go fast down hills seems like a waste of
components. There are other ways to keep the chain on the bike
without having to give up the top half of your gearing!

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

Good points. Ok, I'm convinced.

Thanks.
--
Slack

Slack said:

JD said:

Slack said:

I'm trying to figure out if I want to run a double or triple upfront.

Quoted message said:

You? A triple.

Quoted message said:

JD

Yes, get it straight; triple chain-ring; double chin.
--
Slack - sponsored by In-&-Out

I was LOL, until I started to cry.

Excellent rule of thumb, anyway.

/s

Scott Gordo said:

Slack said:

JD said:

On Mar 21, 5:33 pm, Slack <[email hidden]> wrote:
> I'm trying to figure out if I want to run a double or triple upfront.

Quoted message said:

Quoted message said:

You? A triple.

Quoted message said:

Quoted message said:

JD

Quoted message said:

Yes, get it straight; triple chain-ring; double chin.
--
Slack - sponsored by In-&-Out

Hmmmm, I was thinking about a panini, but a Double-Double is about 2
miles less pedaling...

Quoted message said:

I was LOL, until I started to cry.

Excellent rule of thumb, anyway.

/s

It was cute, for a slacker.

It was nice of him to post his intentions for the ring usage too.
Forget about that big ring, get a bashguard and ride shiite like this:
http://www.spokejunkies.com/forum/uploads/1164057165/gallery_35_32_38623.jpg

JD