specifically roads only big wheel?

[joemarshall]

@goldenchicken

An experienced road unicyclist here in Sweden was appalled by the effect that BA had on his riding after buying a 29er. The wide contact path made him very sensitive to the slightest angle of the road. He quickly sold the 29er and went back to his old 28 frame with a narrow tyre.

But! some months later he bought a Coker and almost went lyrical about it. Now, why doesn’t that fat monster tyre pull him into ‘coning’?

This is also my own experience, on the Coker I seldom have any ‘camber problems’. Only wind & ass problems.

It’s probably because he didn’t pump it up enough.

The big apple doesn’t have as firm sidewalls as a coker, so needs lots of pressure.

He may have pumped it up using a hand pump without a pressure guage, with those you usually don’t get more than about 30 psi in a fat tyre like that, the BA is rubbish at that pressure and likes more like 60 to 65 PSI. Loads of people get caught out by that one.

Once I discovered that, I’ve been able to ride 50 miles plus on the Big Apple no problems, although for 100 miles I’d choose a coker.

Riding super long distances is mostly about being able to stay on and not crash when you’re really tired, with an aching arse and wired up on sugar and energy foods. Coker and Big Apples are much less likely to buck you off randomly if you lose concentration. A narrower tyre may or may not be theoretically good for long rides, but you’re a whole lot more likely to be thrown onto the tarmac hard off one, which is likely to end your ride, or at least make you ride much slower.

Joe
(who rode 100 miles in 10 hours today with no UPDs or falls except for one steep hill that I just couldn’t ride up - on a coker with 110s).

[system]

Re: specifically roads only big wheel?

In message <4392ed1c.675275@newszilla.xs4all.nl>, Klaas Bil
<klaasbil_remove_the_spamkiller_@xs4all.nl> writes
>On Sun, 4 Dec 2005 05:45:40 -0600, goldenchicken wrote:
>
>>A soft tyre ridden along a sloped road would be compressed so that most
>>of it (looking at a cross section) would reside on the up slope side of
>>the rim. I can’t see how this can affect the direction you are going
>>unless you count in the cone effect.

<Big snip>

>And this process is ongoing continuously, so that the direction in
>which the wheel travels is not perpendicular to the slope, but
>somewhat more downhill. To counteract this tendency, you need to
>constantly steer upslope.
>
>QED.
>
>But could probably have been done less wordy.

I couldn’t see from your argument how that would induce a turn. However,
having thought for a while whilst sipping a large gin and tonic in the
bath, in summary your verbose thesis is basically saying that the tyre
splats onto the road on the uphill side

If so, and that is indisputable, there will be a moment imposed between
the force generated by the rider in the centre line of the tyre and the
reaction from the road a little off-centre. This will act in such a
direction as to turn the wheel downhill, unless counteracted by the
rider.

I think this is the correct origin of the turning moment, as it explains
why a large, or underinflated, tyre is more prone to turning downhill
than a narrow tyre - the larger or flatter tyre has the mean point of
contact farther from its centre line than a thin tyre, so the turning
moment is greater.

Glad that we’ve got that sorted out

Wassail!

Martin E Phillips nb Boden, Splatt Bridge
http://www.g4cio.demon.co.uk martin/at/g4cio/dot/demon/dot/co/dot/uk
Homebrewing, black pudding, boats, morris dancing, ham radio and more!
The Gloucester-Sharpness canal page http://www.glos-sharpness.org.uk

[system]

Re: specifically roads only big wheel?

On Sun, 4 Dec 2005 12:43:43 -0600, goldenchicken wrote:

>With the ideal pressure the wheel would go straight?

Maybe so… I’m not able to quantify the two effects, so I don’t know
the break-even pressure (if there is one). But I suspect it would be
quite high.

Klaas Bil - Newsgroup Addict

“erectile function trumps public image - David Stone, commenting on the importance of seat comfort”

[johnfoss]

Back to the original question…

@abbabibble

has anyone made a big(ish) wheel like that?
and what is the biggest skinny road tire size that is currently made today? the largest i’ve found is a 28…
I’ve been curious about it… it’d dramatically reduce the wieght for long distance rides…

700c is probably it; the same tires on those road bikes. I do have a 45" wheel with a “skinny” tire on it; gray wheelchair rubber on an old Schwinn 1 3/8" tubular rim. The rubber is either 7/8" or 1" in diameter. Of course it’s not an air tire, so it’s not light at all. And the ride is HARSH!

I’ve thought about having a skinnier tire for my Coker, but not a lot skinnier. Skinny tire = higher pressure, which = harsher ride, which = more wear & tear on the crotch, which = bad for long rides.

That’s why the Coker is so nice. It’s not just the wheel size, but the nice smooth ride. I already had a bigger wheel, but I’ll take the Coker every time for getting from A to B.

The problem is that the Coker’s tire (and stock tube) are pretty heavy. So I think a moderate reduction in size, aimed at performance road riders, might be nice. Maybe something in the 1.5" range or so. But I’d recommend doing this with a 42" tire as well. That would be nice!

I have also raced on 24" wheels with skinny-skinny tires. Yes, not comfortable for much else, but very light & responsive. Quick off the line for the 100m sprint, and theoretically very well suited to the Obstacle Course.

[podzol]

I suspect there is a phenomenally large differfence in rotational inertia between a coker and a skinny. This could account for the way they handle and the difficulty balancing the skinny.
Blake

[Mikefule]

@podzol

I suspect there is a phenomenally large differfence in rotational inertia between a coker and a skinny. This could account for the way they handle and the difficulty balancing the skinny.

You are right.

It’s not the only factor, but it is very very significant.

I have a standard steel-rimmed Coker, and an unusually light 700c. Comparing the crank:wheel ratios, they ought to behave similarly. They don’t.

This is the joy of unicycling: 3 simple variables: wheel diameter, tyre section and crank length. Choose a combination, and see what you can do with it.