I tend to disagree with Florian on this issue. While it is true that the torque arm must be firmly anchored to the frame with some precision, it is possible with the right equipment to make any frame suitable to accommodate it. I modified Kris’ standard Coker frame to tightly anchor the torque arm on der UberCoker but I had to align the frame and bore a hole slightly off perpindicular to the frame tubing. Then I had to machine a plug so that the anchor bolt could be tightened without crushing the frame leg tube. Without the proper equipment this would be close to impossible to do.
You’ve already done the biggest part by lacing one of your incredible wheels to one (or two) of them.
I still agree with Mike’s assessment. The 36" tire makes the geared unicycle much more stable. A shiftable 36" will be manageable at low speeds in low gear and demonically swift yet still stable in high gear.
I don’t know if they’re available, but he does show a frame/cranks/hub combo for a 36" on his price sheet/order form. …and ok, maybe I wasn’t the first to say it.
Ken,
In Laos, I’ll be riding a regular coker probably with 140’s. I think that shiftability is the key to making a geared coker a feasable touring machine.
I disagree about 29" being the most common size in the future (ok, so maybe its physical size DOES make it more practical). You may change your mind once you try a geared coker. Confession: I’ve never tried a geared 29er.
I had no idea that a coker was so expensive in NZ! We’re so spoiled here.
Would it be possible to engineer some cunning floating mount so that torque arm/frame alignment is less of an issue? I believe some disc brake systems (I think Avid) have a cunning mount that allows the brake to self centre, whereas others like hope etc. require the disc mount to be faced so that the alignment is correct. Might something like that work for a geared uni so that frames that weren’t precision built could be used?
I think there’s an issue here of how practical you want to make it. The ultimate practical touring cycle is getting more and more like a bike with every iteration, adding handlebars, brakes, gears etc. I think there might be a point where people start not bothering with riding these highly evolved vehicles and going back to plain old unicycles without all the added bikey gumph, or just give in completely and buy a two wheeled touring cycle.
Having said all that, I’m definately getting a schlumpf in 29er form, because of the two unicycles in one aspect Ken mentioned, a practical way of getting yourself places, plus a pretty good setup for fast muni. Muni on the coker is fun, but a bit dicey once you’ve put 110 cranks on for distance, whereas a 125mm cranked 29er is fine and dandy for muni.
Incidentally, a coker here costs about a third of the schlumpf cost.
As far as I’m concerned, the only thing that could make a unicycle bikelike would be the addition of a second wheel, but I agree that for many people, simplicity is key.
I think using a geared hub for MUni might be a bad idea (can anybody comment on a Schulmpf’s durability under such circumstances?)
Still, you compared a coker with 110s to a 29er with 125s. On a Schlumpf 36er, I think ideal cranks would be close to 160s; perfectly suitable for coker MUni. …or were you comparing a shiftable 29er to a standard 36er?
The drop impact on a standard unicycle is to the axle only because, ideally, the rider is holding the seat and therefore the frame. The rider doesn’t land on the frame which would impart impact to the bearings.
On a geared unicycle, even the jackshaft style, the drop impact would be transmitted directly to the hub bearings. In the case of internally geared unicycles this impact would be transmitted to the geartrain also.
Florian case hardens his gears and shifting mechanism parts which allows him to make them smaller and much stronger than the ones I used. The bearings are still going to take the brunt of any impact, though.
We’re talking fast muni without big drops, as opposed to hoppy droppy muni. I currently ride a suzue hub with bicycle euro cranks on the 29er, and haven’t broken any cranks/hubs over several years of riding. The only time I’d get more than 6 inches of air would be if I launch off something fast and I only do that on the 29er on jumps or something with an obvious transition.
I think the impact on the cranks / hub is likely to be much larger on a heavy 36 when you drop the uni going fast on the road than on the much lighter 29, even if it falls down something offroad? I know that I’ve broken a couple of pedals by dropping the coker whilst riding fast and not done the same sort of damage on the muni.
Roger unicycle.com and I did talk about this, but we both ride very light (and don’t weigh much) so we thought we’d probably be okay. It’d obviously be stupid to do if you’re someone who needs splined cranks.
I don’t hesitate taking BlueShift off of a curb but I wouldn’t do 4 foot drops to flat like I do on a MUni. As you say, if you’re riding light MUni (smooth trail riding) and not doing big drops it’s unlikely that you would do any damage.
phew, that’s less worrying! To be honest, I’m much more a rider of mountain bike trails on my muni than a drop to flat person, I’ve done 2 foot to flat on purpose three times on the muni just to see what it felt like, but when I ride it on trails it’s rare that I do drops at all and I don’t do anything that doesn’t involve rolling out whilst still riding fast.
Now that is a great idea. Geared down to about .5:1 would give an effective 18" diameter but the 36" wheel would roll over bumps and obstacles with greater ease. Don’t know if there’s be stability problems with a 36" at slow speed though (not being a Coker rider myself).
No offense at all, but I can’t imagine a worse set of trade-offs than gearing down a large wheel for offroad riding. The extra weight of the wheel itself plus the hub would make it not fun. I think a 24x3 with 170mm cranks is plenty slow enough and allows for riding over obstacles pretty well.
Re-geared road unis, I will reserve judgement until I’ve tried out Ken’s schlumpf. I will be interested to see if I have the same reaction I did to my first long distance coker ride. The reaction was along the lines of :
“I have got to get me one of these, no matter what the cost!”.
Two grand and nine months of planning, organising, watiting, custom building later I got my coker and have been loving it ever since. Note that NZers can finally buy affordable 36" wheels with the advent of the new UDC 36" wheel for about half the price of the old cokers. Due to our geographical remoteness postage is always a killer so if we can’t get it shipped by sea things become horrendously expensive.
Re-geared Munis, Tony and I have had the “if these existed what crank length/ wheel size combo would be best?” conversation. I think they would be ideal for offroad racing, which does not require as strong a hub for general free riding and jumping off big stuff.
Having done a fair amount of 12 and 24 hour offroad events I’ve noticed many courses have large sections of relatively flat unchallenging terrain (often fireroads or riding on grass to reach the next technical section). When competing on cokers these sections are a blast because you can really motor through them but a coker is a lot of effort to navigate through more technical terrain (especially at night).
Tony and I both find 150s a good length for riding technical sections (whether that be on a 29er, 26 or 24). With a geared hub and this crank length you could motor through the easy terrain and then switch down to really crank through the technical sections. This sounds ideal assuming small bumps aren’t too much of a problem.
what about gearing down for uphills?
well YOU do not need that but humble Cokeurs like me are unable to climb long hills (and worse, unable to freemount uphill )
I know, I know the answer is “do not expect much from technical gimmicks: just train!” … except that , at my age, progress is very VERY very slow and seething with rage I grumble “If I had a geared down machine!”
If uphills are the problem, maybe what you need is a 29er geared up for the flats. It’s going to be much easier than riding a weird geared down coker really slowly up hills. A 29er climbs easier than a coker with the massive weight difference.
For offroad, I can’t see a geared down coker being any good. The ability to roll over things isn’t a big problem on a 24"x3" anyway, and you have the advantage of being able to use a good offroad tyre, unless you live in a desert you wouldn’t want to coker proper offroad riding in winter. Also cokers offroad are limited in forest riding, where head height is really an issue.
for sure I tested that solution but …
(almost) same problem with 29er : I just climb 3 times further!
(that is around 500m ) then wether my heart gives up or my balance gives up due to change in slope.
Since I am a fairly good climber on a mountain b*ke I suspect that I do not use my forces well (and, maybe, that another cadence will help …hence gear down and up with pedal cadence).
So the question boils down to: does better cadence helps balance? (up to a point: if the uni goes too slowly you sure loose your balance)
none taken whatsoever. I’m thinking merely from an experimental point of view, more for uphills than anything else.
a spectator’s view could be rather like seeing a silly bike rider spinning uphill in a granny gear at walking pace - quite entertaining! (there’s something else to try - super-silly geared down ratios - 1:10 anyone?)
Oh that’s what you meant. Sure I’d love to try a 1:2 or 1:5 or 1:10 or whatever geared 36er to see what it’s like. But for actual offroad riding, a 24x3/170 if it’s steep or 29x2.3/150 if it’s reasonable are the way to go. SO much lighter.
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