700c lightweight wheel, advice needed

I experimented with this last year. Originally my unicycle had a 700 x
45c tire. Using the same hub and spokes I installed a narrower Mavic
700c rim and used a 700 x 28c clincher tire and inflated it to 100
psi. The decrease in rolling resistance was amazing but any advantage
I gained in a decreased rolling resistance I lost due to the
significantly smaller diameter of the narrower tire.

One day while out on a ride I was about 10 miles from home on a pretty
busy stretch of road. Suddenly my tire blew out. The load BANG of the
exploding tube and the nasty upd so close to moving traffic is
something I won't forget all too soon. I'm not sure if it was the
explosion of the tube or the force of the rim suddenly smacking the
ground but my rim had "taco'd" big time! It bent so bad the wheel
would no longer turn. Fortunately I had my cell phone in my pack and
was able to call for a ride. I decided to switch back to the original
rim but this time I installed a 700 x 35c kevlar reinforced tire which
worked pretty well. I've recently built a 36'er so I'm no longer
riding the 28".

--
unipsychler

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I would NOT go with a 24 spoke rim. As you stated, it would be
considerably weaker and it would be carrying your full weight, unlike a
bicycle, where the weight is supported by 2 wheels. I don't believe the
slight weight savings would be worth sacrificing the strength of the
wheelset.

--
Krashin'Kenny

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Well, there is a lot I don't know and haven't done. There's too little
time and money to work on all these areas. Since the same is true for
you, though, you might consider for this particular project:

[Z] Use as deep a rim as possible (not wide, but deep). This helps
carry the lateral and radial stresses that the spokes are not. I see
from the catalog that the DT Swiss RR1.2 is quite deeply dished, is
pretty narrow, and has a large number of different drillings (20, 24,
28, 32), comes in black or silver, and runs approx USD$80.

[Y]It might be easier, cheaper, faster, and probably just better if,
given Z, instead of reducing the number of spokes you reduced the
diameter of the spokes. So go for 15 gauge or the lighter triple-butted
(14/16/15).

[X]Go for lightweight tubes.

[W]Don't expect brakes to work because of rub on hill climbs, though
it's possible. But you don't believe in brakes, if I remember
correctly.

[V]Save rotational weight also by changing your footwear, and if the
case applies to you, reducing the weight of your legs (which mostly go
up and down, but you get the idea).

I haven't tried this, so this is just the approach I'd take if I were
trying to do this for myself for the first time.

Of course, this would not be a setup for rough or cambered ground.

One neat thing is that while training, you can put on a Kevlar tire to
reduce punctures (heavy) but then you can trade off to a lighter, more
fragile tire when you really want to be lighter under more sanitary
road conditions.

--
U-Turn

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unipsychler said:

and used a 700 x 28c clincher tire and inflated it to 100 psi. The
decrease in rolling resistance was amazing but any advantage I gained
in a decreased rolling resistance I lost due to the significantly
smaller diameter of the narrower tire.

I use a 700c x 28mm tyre at the moment, although I don't run it at
quite such a high pressure. There are no "practical" advantages to
the skinny lightweight set up. I have no doubt that a 29er with a fat
juicy tyre would be faster over a journey. But we don't do this for
practicality, do we?🙂

unipsychler said:

One day while out on a ride I was about 10 miles from home on a pretty
busy stretch of road. Suddenly my tire blew out. The load BANG..

As it happens, I had a high speed blow out on my first ever ride on my
28, with the standard tyre and tube - but that was because the tube had
been put in twisted at the factory.

--
Mikefule

Let every man so *p*itch his song
To help his neighbour sing along
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The main reason for reducing spoke count on a bike wheel is to reduce
drag, not weight. With the speed a unicycle goes I would reckon it's
better staying with more spokes (certainly as the single wheel has to
take all the weight). As I mentioned before, there's a pair of narrow
700c rims in my attic going spare - you're welcome to grab one while
you're down here for the muni weekend (or before if you're around).
They're 36-hole Rigida rims, slightly narrower than Open Pros - I used
to run 20mm tyres on them. Nothing flash, but they're straight,
eyeletted and free. You've inspired me to try to build something out
of the other one - I'm collecting parts now.

Rob

--
rob.northcott

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Err, isn't a clincher rim just the normal sort? ie, not for tubular
tyres that are just glued to the rim or somthing like that. It's the
width of the rim that's important, not it being a clincher rim.

What's the advantage of a narrower hub? I could uderstand not using a
silly-wide coker hub, but I can't say I've ever noticed the hub width
on my unicycles (all standard hubs) slowing me down. Is it a case of
'more niche than thou'?

--
johnhimsworth

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johnhimsworth said:

Err, isn't a clincher rim just the normal sort? ie, not for tubular
tyres that are just glued to the rim or somthing like that.

Correct. The Open Pro rim Mike mentioned is pretty much the standard
good-quality road rim these days - it'll take tyres from about 20mm up
to 28mm, is nice and strong, and quite light.

johnhimsworth said:

What's the advantage of a narrower hub?

I presume he's just going for minimum Q, which theoretically should
make for slightly more efficient pedalling.

Rob

--
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I wasn't particularly after a narrow hub. I wasn't after fewer spokes
for its own sake.

The point was I wanted a lightweight wheel. It was suggested that the
best lightweight rims would tend to be designed for fewer spokes. The
only unicycle hub made for fewer spokes happens to be a narrow one.
Hence the question.

I certainly wouldn't choose narrow for its own sake. I can see no
advantages to narrow, and several disadvantages.

--
Mikefule

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