My long term project is to build a lightweight skinny tyred 700c. Yes, I know it’s daft, but so am I.
At the moment, I have the Nimbus I frame (the one with the Y fork crown, not the H fork crown), the standard wheel, but a lightweight tyre.
The Nimbus I frame takes a 22 mm (approx) seatpost.
Searching Unicycle.uk.com, I found the KH aluminium frame (link above).
This is way more expensive than a standard frame. Is it significantly lighter and better? As it takes a 27mm seatpost, that suggests to me it might be “overbuilt” for more rugged use, and not appropriate for my intended use. Any savings on weight might be offset by the extra weight of the thicker seatpost. Have you used one (or the smaller models?) and if so, what’s the quality and style like? What other advice can you give me?
Moving on from that, my preferred saddle at the moment is the Miyata, but that needs a special seat post. Any ways round that? I’ve heard of rail adapters, but never seen one close up. Sounds like extra weight and clutter to me. Any comments?
The plan for the uni is lightweight and elegant: a rapier, not a broadsword.
Shouldn´t you ba able to fit a 700cc wheel into a frame for a 26" wheel?
I mean a 26 x 3" tire should be almost the same size as a skinny 700cc tire.
I have always wanted to build a unicycle witha skinny racing bike tire I hope you make one of your famous Mega-long-writeups that you do, when you are finished building the uni.
I can’t see a custom built frame being any lighter - it’d probably have to be steel, hence less (if any) weight savings, and I’d guess it’d be a tad more than £80.
The rail adapter thing you need might be this but don’t take my word for it.
I’d have thought a lighter wheel would be a better bet in terms of the weight affecting the riding, being rolling mass. You’re not on a 20mm tyre yet, are you?
Unlikely to be anywhere near hockey for ages due to this new job thing.
No, I reckon anything smaller than the 28 mm tyre would be wasted on the standard Nimbus rim. I “need” (in the technical sense of “would quite like to have”) a narrower lighter rim.
I’m just looking at all options here.
Experience shows that a lightweight wheel is more responsive, but slower over a journey. It’s not only responsive to rider input, but also to input fromt he other end: bumps and changes in surface. You’ve had a brief go on the 700c x28mm. It feels very different from any other unicycle. I reckon with a skinny rim I can get down to around 20 mm, and have a really temperamental thoroughbred to ride.
yeah, but thats not going to happen. i tryed to get mike to try a nanorapter 2 years ago and no dice. he already has a 700x28 of some sort, sounds like he wants to improve on that model.
I agree with jagur - I think it would look a bit odd with a very skinny wheel in a muni frame.
It would be cool if you could adapt a pair of straight road racing forks (chop off the dropouts and braze on some uni bearing holders). Might not be that easy though because of the angle of the steerer tube. You could use the crown of a road fork and braze on some straight legs. A possible downside might be that bike forks could be too flexible to take the pedaling forces of a unicycle without the wheel rubbing on the frame. If you could build a nice narrow frame to suit the wheel it would just look far cooler than using a normal unicycle frame, but probably make no difference to the ride.
It looks like Quax virtually makes the machine you want, very lightweight and skinny with just 20 spokes. The only problem is it aimed at meeting the 24" rule for races so obviously is not 700c. I have got the spec and picture on paper but couldn’t see it on the web.
the kh frame is really light, so it would fit your purpose. Also, the seatpost (which would have to be a kh post) is exceedingly light. However, the KH seat is substantially heavier than a miyata. I don’t know, but I think a KH gel seat is lighter. It’s smaller, anyway.
I agree that a tiny tire wuold look somewhat out of place in a KH frame, but if you care only about weight, I think it’s the way to go.
The KH frame is, aesthetically, the best mass-produced frame on the market, by far. The low weight is a nice bonus.
The 27.2mm seatpost is a much better size for a unicycle seatpost than 22.2. For one thing, 22.2mm diameter doesn’t provide enough surface area to keep the seat from twisting on dismounts, unless you really crank down on a quality seat clamp bolt. I’ve never found a quick-release that will keep a 22.2mm seatpost straight; it should be possible with a 27.2mm seat clamp. The 25.4mm seatpost clamp on some of the Nimbus II frames is also an improvement over the 22.2mm.
27.2mm is also the most common size for bike seatposts, which means the selection you’d have would be much larger; assuming, of course, that you also get a rail adaptor. I don’t like the KH rail adaptor all that much, because the brake attachment is just extra weight and complication for most riders; I like the simpler adapters that Steve Howard made, but I don’t think they are commercially available right now.
For me, a big negative on the KH frame is that the seat tube is welded onto the crown tube, rather than two split crown tubes being welded onto the seat tube (as with the Nimbus frame). This means that the effective range of adjustment for the seat is less than 3cm (from bottomed-out to "min-insertion’). If you are the only person who ever rides your unicycle, and if you don’t adjust your seat for different terrain, that might not be that much of an issue, but to me it seems like a design flaw.
Overall, I would say that the functional advantages of the KH are fairly small for most applications. If you don’t need a brake, and you’re not doing one-foot tricks or hopping a lot, I think it’s hard to justify the expense, with the perfectly-acceptable Nimbus II being one-quarter of the cost. It won’t look as nice, but it will work just fine.
I’m surprised that no one has mentioned the bearing holder size on the KH frame is different than the standard 40 mm OD bearings found on most uni wheels
and also, the weight of a frame won’t make NEARLY as much difference as rotating mass (tire, tube, wheel, spokes, and even pedals)
maybe go tubleless before getting a lighter frame? it will seriously only make much difference if you are hopping or if u will be carrying the entire uni around, otherwise rotating mass is key
and the new low-profile, dual density foam KH seat is really comfortable and lighter than the standard fusion, it is also tilted back a bit more w/o a rail adapter
i’m not exactly sure, but I think Darren Bedford (bedfordunicycles.ca) might have the KH frames cheaper than UDC as well
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