Lightweight 29er

So I recently acquired a schlumpf 29er (the road/square-axle version,
'coz it was much cheaper!), and after a while trying (none too
successfully) to ride it with 125 cranks, I've now put 140s on it. The
difference is tremendous, it's controllable but I can cruise along at
huge speed ;-) compared to previous ungeared 29"/26" unis I've
tried...(14-16mph doesn't even seem fast...!)

However, I am wondering about putting the 125s back on at some point.
My feeling is that I'd not only need generally much better balance
etc., but also I'd want a much lighter wheel - as is, it just takes too
long to do anything 'coz you have so little leverage. (Yeah, ok - or my
legs just aren't strong enough ). At present I have the Nimbus 29er
rim and a Kenda Karma folding tyre - iow, the lightest rim available
from UDC, and about the lightest 29er tyre going also.

Hence, I'm wondering about going much narrower - and accepting that
this'll be a largely road-only machine. Maybe a 1.6" tyre or so - I
don't think I want anything quite as extreme as the Bacon Slicer or
Road Razor, but Nimbus 28er-ish, perhaps; I was thinking of maybe a
Schwalbe Marathon Racer, which in 700C*38mm weighs 425g (compared to
the Karma's 600ish!). However, I'd also want to move to a lighter rim,
and I'm worried about rim strength: one can easily get 29er "Mountain
bike" rims weighing in the 400g range, but presumably these are built
to withstand only half the weight of a rider on them, rather than the
rider's whole weight being on one wheel. "Tandem" rims are probably
designed for equivalent weight (maybe even more, given the weight of
the bike, tho generally not for off-road usage), but are often just as
heavy as e.g. the nimbus 29er, and frequently have 48 spoke holes (not
an option!). Narrower rims may be stronger for the same weight, but I'm
wondering what experiences other RSU readers have had in this
field????

Many thanks, Alan


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I use 125s on my schlumpf, and I know what you mean, it is a bit of a
beast. But you do get used to it.

One thing that might make a big difference for road riding is using a
slick high pressure tyre, they're much better, you'll get much more
resistance from knobs even on a light weight muni tyre. I'd consider
first trying a lighter weight smooth tyre (whilst it isn't ideal, you
can run a tyre on a too wide rim without problems).

For road riding, any strong 36 hole road rim will be fine, that's what
everyone used to use before the KH & nimbus rims came out. They don't
run the big apple nicely, but are fine with narrower tyres. You also
remove much of your ability to do muni, as muni tyres suck a bit on the
narrower rims. I used to use a mavic touring rim on my 29er.

If you do end up trying the rim change, if you could report back on how
it goes, that'd be great, I've been kind of considering something along
these lines.

Joe


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My 29er has a Mavic T520 rim on it that's just 19mm wide, half the width
of a Nimbus! I don't know how much it weighs but it's not a lot.

It's pretty versatile, I'm using it with a Kenda Klaw 2.1" at the
moment and it's the only problem I've noticed is that the tyre folds
over a bit if I try to hop up something steep sideways. That's
obviously not going to be a problem on a road uni!

As far as strength goes it's been fine so far despite being
second-hand. Bike rims are designed to take half the rider's weight,
plus half the bike's weight (which could be quite a lot on a touring
bike!), and go over bumpy roads at much higher speeds than unicycles
do. I'd definitely reccommend a bike rim if you want a light road 29er,
if you don't like the narrow bike tyre you could always use a Big Apple
2.0" on a rim like mine, at the pressure you need for road riding it
should be fine.


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I'd guess that the wheel build is more important than the actual
strength of the rim. Probably a good idea to use a decent quality rim
(box section, eyeletted) and probably not an ultra-narrow racing rim
(although MikeFule's Open-Pro is holding up OK as far as I know, even
with some mild off-roading), but bike rims are stronger than people
think - although unicycling does put more sideways stress on rims than
bicycling, so putting more importance on the wheel build quality.

Rob


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