Quick question about seat tube length

[finnspin]

Originally Posted by Scoox

Does anybody know how the Impact gravity hub and the KH Spirit hub compare? If hub is good enough, I could just get the Gravity, swap the cranks and be done.

I haven't heard of any problems with either hub yet. They weigh about the same, and as long as they don't break, there is really not much difference a hub can make.

[Scoox]

Originally Posted by song

Thank you for that tip! I actually found a modern UDC Schwinn 24 at a garage sale, and I keep it at a relative's house for when I visit. Not being able to practice one-footed skills at those times has been a minor but persistent source of frustration. I had thought of wrapping a piece of innertube around the fork, but never got around to it. The hose clamp idea sounds much tidier and more effective.

Scoox, it's kind of funny that you're wondering whether all these Chinese-made products can be shipped back to China for you! I don't know what the answer is, it's just a funny situation. I guess it says more about the world we are living in than about what sort of unicycle you should get, though. Oh well, good luck!

LOL yes indeed, we do live in a mad world. Goudurix are working out a quote for that Gravity frame, at 56 USD it's a steal, so what I might end up doing is getting a full KH20 and then just swapping out the frame.

I mean, this is a minefield. There's very little info about parts compatibility and too many 'standards'. For example, I have no idea if a KH seat post and an Impact saddle would fit together, and there are several different saddle interfaces. It seems the whole unicycle thing is still in it's infancy, a bit like trials bikes 8 years ago.

[Scoox]

Unicyclist.com's China rep just got back to me, says they can sort out my custom build but I need to wait till the 17th of May as he's not in China ATM. He says, however, the Impact hub is lighter and also very good.

The KH20 weight is quoted as 5.4 kg on KH's own website. However, based on data from UDC (UK) it's actually less, but then they also mention the KH20-LN variant on the same page, I wonder if the 5.4 kg is for that model, although 400g for a few extra cm of alu tubing seems hard to believe. UDC (UK) quote the weight as 5 kg, and it seems all their weight values have been obtained empirically, not based on marketing blurb. For my own sanity I've put together a per-component weight comparison of the KH20 and the Impact Gravity stock configurations. Rim tape and inner tube weight are guessed values since there's no info about these for either model, I've just assuemed both to be the same weight. Some values are quite interesting, and, as you can see, both models are similar in weight, which I think is pretty good news.

(click here to view table on Google Sheets)

[johnfoss]

Originally Posted by song

I had thought of wrapping a piece of innertube around the fork, but never got around to it. The hose clamp idea sounds much tidier and more effective.

The downside of the hose clamp is that it will leave marks on a painted frame (and possibly plated ones too). You could just put some tape (or old innertube) on first.

I am reminded that a lot of the earliest USA Inc. competition racers didn't put their foot on the fork for one-footing. Probably because they had Schwinns. I have pictures from the 1981 National Unicycle Meet of the great Floyd Crandall (and others) zooming down the track with their non-pedaling foot just kind of angling out in front of them like a La-Z-Boy recliner.

[Scoox]

I think I've made up my mind, it's going to be the Impact Gravity black but with the black rim and 137 mm KH Spirit cranks. After watching some videos I don't think I'm going to be doing any flatland and if I do any sort of trickery it's going to be pure trials. The KH cranks with their polished metal finish and generous Q factor should be kind on my ankles. If I can get the frame from Goudurix it's going to be a really good deal.

While watching videos I noticed titanium hubs are quite popular among uni trials riders, maybe a future upgrade once I've got the basics down. I've also seen carbon fibre saddles, are they very expensive? Couldn't find any on unicycle.com.

[elpuebloUNIdo]

Originally Posted by Scoox

it's going to be pure trials.

SIF is the pure trials!!!

[johnfoss]

No hops is the pure-pure Trials!

Okay, let's call that the pure Rolling Trials. Rolling has its limits...

[finnspin]

Originally Posted by Scoox

I've also seen carbon fibre saddles, are they very expensive? Couldn't find any on unicycle.com.

I'm not sure if they are expensive right now, it's more that they are almost impossible to find. No one produces them anymore, and the people that have one (like me) wouldn't part with it. It's more important for street and flat though, not that important for trials.

The only reasonable definition for pure (unicycle) trials is overcoming obstacles on a unicycle without putting your foot down, with no consideration to style or technique.

[OneTrackMind]

Originally Posted by finnspin

I'm not sure if they are expensive right now, it's more that they are almost impossible to find. No one produces them anymore, and the people that have one (like me) wouldn't part with it.

I have one on my 36 and it definitely will be mine until I can no longer ride any unicycle.

[Alice Arctan]

Compulsion has a curved carbon base, undrilled, for $100.

[Scoox]

$100 for just a seat base is a bit much. Never done any work with carbon fibre but if it's just layers of the stuff and epoxy I wonder how hard it'd be to diy one.

BTW I emailed Kris Holm about the neck length, here's what he said:

The KH20 used to be made with a 150 mm neck and 250 mm neck (LN). Recently we switched to a single model with a 200 mm neck. So yes, the LN has been discontinued. It was actually rarely produced because while riders liked it, many riders couldn't fit the longer neck.

This is good news because 200 mm seems like a happy middle ground. It seems the guys at UCD China got their facts wrong when they told me it was 150 mm, either that or they still have stock of the old 150 mm model.

I actually quite like the KH20, with the flat crown it probably makes a more versatile machine than the IG.

[JimT]

Originally Posted by Scoox

$100 for just a seat base is a bit much. Never done any work with carbon fibre but if it's just layers of the stuff and epoxy I wonder how hard it'd be to diy one.

Here are a couple past threads on a DIY carbon fiber bases:
http://www.unicyclist.com/forums/sho...d.php?t=109074

http://www.unicyclist.com/forums/sho...age=4&langid=5

[Scoox]

Wow that's pretty good, especially the second one. I'll start off with an off-the-shelf saddle and maybe do one of these after.

I don't know how he made the moulds, but it's clear the results are better than using a vacuum bag.

The way I would do this:

1. Make a saddle from a solid block of wood that can be bolted to a seat post for checking fit and form
2. Send the wood prototype off and have it 3D scanned
3. When the 3D model comes back, import it into 3D modelling software (e.g. Fusion 360) and modify it to make it perfectly symmetrical, and then make a slightly bigger negative of the model as a counter-mould.
4. Finally, have the two halves 3D printed or CNCed from a block of ABS or whatever.

I bet that'd cost more than just buying the $100 one! But it'd be a custom saddle. In China 3D printing services are reasonably inexpensive.

Anyway, I'll add that to my stash of DIY projects.

[Pinoclean]

Originally Posted by Scoox

$100 for just a seat base is a bit much. Never done any work with carbon fibre but if it's just layers of the stuff and epoxy I wonder how hard it'd be to diy one.

BTW I emailed Kris Holm about the neck length, here's what he said:



This is good news because 200 mm seems like a happy middle ground. It seems the guys at UCD China got their facts wrong when they told me it was 150 mm, either that or they still have stock of the old 150 mm model.

I actually quite like the KH20, with the flat crown it probably makes a more versatile machine than the IG.

Also not mentioned here the long neck KH's neck bends like spaghetti. Mine curves forward and a rider I live with bent his to the side.

Here is the bent to the side one in all its glory..
https://drive.google.com/file/d/0B_M...ew?usp=sharing

[Scoox]

Originally Posted by Pinoclean

Also not mentioned here the long neck KH's neck bends like spaghetti. Mine curves forward and a rider I live with bent his to the side.

Here is the bent to the side one in all its glory..
https://drive.google.com/file/d/0B_M...ew?usp=sharing

Damn! Which year model is that? Has anyone experienced this problem with the lastest model?