Astoundingly cheap commuters

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

Quoted message said:

Zebee Johnstone said:

But then I suppose I can pick up a front disk and brake for $150 if I
look hard enough.

Probably even less, if you stick with cables. For hydro it's a touch more,
but the Shimano Deore offerings are both pretty good, and I've also heard
good things about Avid's cable brakes.

--
Dave Hughes | [email hidden]
"Contrary to popular belief, Unix is user friendly. It just happens to
be very selective about who its friends are" -- Kyle Hearn

Good point about the hydros. I got so fed up of my Hayes hydros playing up I
changed them to Avid BB7s. Bloody good move IMO. Far less trouble and they
feel much better - more modulation.

Me

On 2007-06-03, TimC (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

On 2007-06-02, Zebee Johnstone (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

In aus.bicycle on Sat, 02 Jun 2007 13:25:23 GMT

PeteSig said:

Incidentally, does your recumbent have a smaller front wheel (eg 20"😉 I'm
not sure about the physics of it but I do believe discs should be more
effective on a small wheel than a 26" as they are proportionally bigger
compared to the rim. Thus greater braking leverage. Someone here will tell
me if I'm wrong or not.

It's a 20" front. No idea about the physics but it does seem
intuitively likely.

Whoops, forgot to look at the disk brake situation. Anyway, rim
brakes:

Quoted message said:

Torque is decreased at the hub because of the smaller radius, but
that's irrelevant because that torque has to be converted back to a
linear force at the bottom of the wheel. Think of the brake as being
some kind of linear brake that is sitting some distance off the
ground. It makes no difference if it is 20" or 26" off the ground,
the same lateral force is being applied.

I think.

So no change for small vs large.

And disk brakes:

For a given force on the disks, you get a given torque. Torque is
force multiplied by radius, so the linear force is going to increase
because of the smaller radius.

Damn, your intuition is better than mine. I blame the lack of coffee.
Damn weekends, I don't get to drink coffee for 2 days in a row.

--
TimC
Just keep in mind that when you are using TRANSFER, you are not
programming, but hacking. All else follows logically from this
premise, Grasshopper. -- James Van Buskirk in comp.lang.fortran

TimC said:

Torque is decreased at the hub because of the smaller radius, but
that's irrelevant because that torque has to be converted back to a
linear force at the bottom of the wheel. Think of the brake as being
some kind of linear brake that is sitting some distance off the
ground. It makes no difference if it is 20" or 26" off the ground,
the same lateral force is being applied.

I think.

Surely the torque from a wheel radius of 13" acting against a 3" radius disc
is going to be a lot greater than that from a 10" radius wheel acting agaist
the same 3" radius disc?? Hence the braking power of the disc on the smaller
wheel is greater.

Caveat: I am no engineer nor mathematician

Cheers
Pete

In aus.bicycle on Sun, 3 Jun 2007 12:21:48 +1000

TimC said:

For a given force on the disks, you get a given torque. Torque is
force multiplied by radius, so the linear force is going to increase
because of the smaller radius.

Damn, your intuition is better than mine. I blame the lack of coffee.
Damn weekends, I don't get to drink coffee for 2 days in a row.

I just figured that swept area of disk as a proportion of size of
wheel was greater for the smaller wheel.

Zebee

M Bison said:

On Fri, 01 Jun 2007 02:06:20 -0700,BTHumble wrote:

<snip>

Quoted message said:

I reckon a penniless uni student could fully equip themselves with
bike & gear for under $200, which is only about 10 weeks' commuting at
Canberra bus ticket prices. Back when I was at uni you couldn't buy a
bottom-of-the-range K-mart MTB for that...

Which makes the bus half the price if the bike only lasts 5 weeks!

Oh ye of little faith!

BTH