Quick question about seat tube length

Hi again, it’s me, the guy with the silly questions.

I’m curious about seat tube length and its effect. A lot of riders regard the KH20 very highly, however its seat tube is very short at 150 mm. The Nimbus Equinox, for instance, is available in 300 and 400 mm seat tube lengths, I could be wrong on those numbers but the tube definitely looks a lot longer than the KH20’s.

So, does seat tube length even matter? KH unis are regarded by many as the best you can get, and I’ve seen some pics of older KH20 versions which actually had longer necks, so the move to a shorter neck must have been intentional. Just wondering what’s the advantage of the shorter neck. Basically my concern is that I could end up hitting my knees on the seat post clamp—done it before on bike stems and it’s not fun.

Cheers :slight_smile:

Yeah, now that you mention it, I do remember KH20s having a long-neck frame in the past.

It’s usually your ankle, rather than your knee, that gets hit by the seatpost clamp, or so I’ve heard, and avoiding that problem is indeed the main reason usually given for preferring a long-neck frame. My sort-of trials uni has an Impact Reagent long-neck frame, and I like it a lot. Goudurix had them on sale a month or two ago. Not all long-neck frames are the same length. Mine, at least, is nowhere near being too long for me, and I am only average height.

My opinion of KH unicycles is that they are overrated and overpriced, though I do think they are awesome anyway, just not quite as awesome as one might hope. There were terrible problems with KH hubs, and KH took years to fix the problem, but it’s fixed now.

Damn I was all set on getting one. That Equinox is regaining appeal. The other option would be to frankenstein it.

If the frame has a long neck, the range of possible adjustment for your seat-post will be increased. If you’re a beginner, you might benefit from playing around with seat height. SIF (seat in front) and freestyle riding, for example, use a higher seat, while SI (seat in/under) and flatland riding use a shorter seat. I did a lot of experimenting with seat height early on, and I was glad my Equinox frame allowed me a larger range of adjustment.

On a side note, I wish the neck on my 26" Oracle frame were a tad longer; the seat post that is compatible with the Shadow handle comes in one size, and to get the seat high enough, I’m raising the post past the minimum insertion point. So far, so good.

If you think you might be letting others try your unicycle, it’s nice to have a range of adjustment. The Equinox long-neck frame, however, is too tall for most kids, even with the seat-post fully inserted into the frame. I assume you’re tall enough for the Equinox.

My repertoire doesn’t include any techniques causing the seat-post clamp to catch on any part of my body. Some riders have referred to this issue, but I’m guessing for the large majority of riders, it’s not an issue. Same for me with the Equinox’s square crown. Maybe various leg wrapping techniques create an issue with the crown. However, I have gotten more utility out of having the square crown, particularly for one-footed techniques.

Lots of riders trash the Cyko-Lite tire (stock with the Equinox) on the forums. I think these are either very advanced riders, or riders performing a lot of gapping with lower tire pressure. The Cyko-Lite is long-wearing and it doesn’t totally suck for a variety of riding conditions.

Regarding the 25.4mm (Nimbus) vs. 27.1mm (KH/Impact) diameter seat posts: The only problems I’ve had with the 25.4mm seat posts on my Equinox and Oracle…involved the failure at the top of the seat post where it forms a “T” and attaches to the seat…which is not really caused by diameter.

I say go with the Equinox!

KH Trials 20 used to be available in long neck and short neck versions. Maybe the long neck has been discontinued. Still advertised on the UDC Australia site, though out of stock

For letting others have a try I have a second trials uni made from my leftover parts with a shorter seat post. (I crossed my old KH Onza with an Impact Athmos putting the Impact wheel and Fusion saddle in the KH frame.)

The white Impact rims are really pretty.

According to Unicycle dot com, the Equinox is 2 pounds lighter and $175 cheaper.

“Frankensteining” is usually a more expensive option. Goudurix, which is located in Montréal, charges very reasonable prices for shipping to the US. They have the Impact Gravity longneck frame on sale right now for $56, which is less than half the usual price. That frame has a fork that is completely rounded, though, so learning any one-footed skills on it would be very difficult. I also don’t know where you’d get your wheelset right now without spending a ton of money.

Edit: The one problem I did have with Nimbus stuff was that the alloy seat post snapped when I was hopping up the stairs. I replaced it with a Nimbus CrMO seatpost, which is a bit heavier, and have not had a problem since then. I’m not sure if those seatposts are still available, and I don’t know what KH seatposts are made of. Oh- and I had a set of Nimbus Venture 2 cranks that got a bit wiggly after a year or two. I don’t think KH cranks will do that. They are very strong.

I’m in China though. I just noticed a pic of the KH20-LN meets all my requirements exactly. The Equinox is OK but I prefer the 27.2 mm seat post standard for spares availability reasons. The Impact Gravity looks really nice, but how do the hub and cranks compare to the KH20? Would a KH20 hub with 32 mm bearings fit an Impact Gravity frame? The problem then becomes getting the actual wheel.

Yes, but there’s also a flip side to that, being that the lowest possible setting is however much higher than a short neck frame.

Some people like their seats to be very low for Trials, Street and Flat, so a shorter frame allows for this. The downside is less length of tube for your seatpost to move around in.

If you do a lot of tricks where your legs and feet are moving around above the wheel (I guess your legs almost always are), NOT having the clamp in certain places can be a good thing. In my days of learning/doing Freestyle (before those other disciplines existed), we had Miyata unicycles with short frames, then one or two extension posts, then a standard sized seatpost in the top extension post. So for most riders, there were two clamps to bang your knees into. Ouch! This is why Freestyle-oriented unicycles like the Nimbus Eclipse put the clamp up high, away from the “knee zone”. A tall frame will move that clamp out of the way (if it even matters for you), but will limit how low your seat can be. A short frame gives you more flexibility, but less range of adjustment for any seat.

All other things being equal, the choice would be obvious. But of course all other things are not equal, which is what keeps these kinds of threads from being really short. :sunglasses:

Not really, but definitely more of a challenge. Imagine learning to ride one-foot on a Schwinn. Slippery chrome at about a 45-degree angle. People would stick grip tape, or even little squares of old carpet or a simple hose clamp, and they were much better foot support. You can do the same with a round crown. It may not be pretty, but a basic automotive hose clamp can make a huge difference on one of those frames, with the screw at the top, of course.

A round bridge doesn’t bother me at all. I do like the Impact Gravity frame a lot, I think neck length is spot-on, but I prefer the KH20 wheel and cranks. I know frames are sold separately but what about wheelsets? And then, would the KH hub be compatible with the Impact Gravity frame, if I use the correct bearing? Would I need different spacers?

It’s a pity Kris Holm have gone so short on neck length, if it was a mere 4~5 cm longer it would be ideal. For a given seat post, too short a neck limits the maximum height, and too long a neck limits the minimum height. I guess one could always get a longer seat post for the short neck, but strength compromises are made and the clamp can get in the way as you guys said.

Just check what buying all the parts you like would cost compared to buying a prebuilt uni, it’s usually pretty much the same. Last time I checked you could buy wheelsets seperately, but there don’t seem to be any on unicycle.com right now. You would need the new bearings which come with the gravity frame and new spacers. Just send the guys at unicycle.com an email with what you want, and they’ll probably make it happen for you.

They aren’t really prebuilt anyway as they parts in a box. UDC Australia will happily swap parts in an out of a new uni at the list prices and get me whatever I want if we can find it in UK or US. Just have to wait for their next shipment which isn’t usually very long.

I’d say go for a second hand cheapo, and then:
1- ride it until you break it
2- it breaks you and ends up collecting dust in the basement like 90% unis.
If 1 then you can reward yourself to a KH, if 2 you won’t have an expensive KH collecting dust in the basement.

I come from a BMX and Trials background (ok, in the 90’s that was), and unicycle has very very little to do with those two sports even if the gear has some resemblance.

I’ve just emailed UDC Australia and Goudurix to see if they accept international orders. Taking the Frankestein route is a tiny bit more expensive but not by much. If I can get that frame off Goudurix then it would actually come out cheaper than buying an either an Impact Gravity or a KH20.

Anyway, here’s what I want:

If a KH20 with a longer neck was available, I’d buy that. I basically like the KH hub which is made from a single piece of steel and has nice big flanges. I also prefer the KH Spirit cranks because they have a generous Q factor. Do you guys know if KH Spirit cranks would be compatible with the Impact Gravity hub? Does anybody know how the Impact gravity hub and the KH Spirit hub compare? If hub is good enough, I coul just get the Gravity, swap the cranks and be done.

If I can’t get the bits separately, an option would be to buy both the KH20 and the Impact Gravity, franken one to my taste and stein another with the bits I don’t want, then sell the latter, or sell the bits individually. Unfortunately the unicycling community here in China is not as vibrant as it is in some western countries so it could be a while before I rid myself of the leftovers.

Just saw your message. Trials is different in many ways but my gut tells me I’m going to love unicycling, because unicycles are mechanically simpler and because of that they are pretty much always good to go unlike a trials bike which usually requires a bit of tweaking before every ride. Portability is also a huge bonus for me, being able to easily throw the thing in the boot or on the bus and ride virtually anywhere, even indoors when it’s raining outside. It’s like learning to walk all over again. I honestly can’t think of any sport involving tyres that’s more rewarding, exciting and convenient than unicycling.

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!

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.

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.

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)

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. :slight_smile:

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.