Wider hubs?

Unicycles and Equipment
1

As I keep reading here, and as seems obvious at a glance, the Coker wheel isn’t that strong - or, more accurately, stable. Th problem is it’s a massive disc with a narrow hub, so that the spokes on opposite sides are nearer to parallel than they would be on a smaller wheel. There’s plenty to stop the wheel going egg shaped, but nothing to stop it going pretzel shaped.

Years ago, I rode a penny farthing with a wheel that was about chest/chin high to me (probably a 60 inch?) and the rim was very narrow indeed, with a solid rubber (or similar) tyre. The difference was that the hub was a fair bit wider than on a modern unicycle, giving the spoke pattern more width, and the rim more lateral stability. The disadvantage was that the pedals were further apart, encouraging a rather bow-legged pedaling style.

It strikes me that the only distinctive thing about the Coker is the tyre/rim combination. Coker make the tyres and tubes, and the rims (or equivalents) are not available from elsewhere (correct me if I’m wrong). The frame is fairly standard except for length and everything else is bog standard.

But… if there are people clever enough to make geared hubs for unis, surely it would a ‘fairly’ simple task to make a hub say 1/2 as wide again, giving the spokes a wider angle and making the wheel easier to true, and more rigid. This would in turn necessitate a new uni frame with a wider crown and the forks further apart, but as the Coker frame is nothing to write home about, and there are plenty of frame builders out there, I doubt this would be a problem.

So what I envisage is a Coker with the hub maybe half as wide again, and forks suitably spaced to accommodate it, producing a ride with all the benefits of the big wheel, but with more structural stability. What does anyone else think?

2

Agreed a wider hub will produce a stronger wheel but…

… one of the best features of the Coker combination are the heavy tyre/rim coupled with the short distance between pedals creating a stable flywheel…
Thus (especially with short cranks) there is much less oscillation at speed.

I’ve seen racing unicyles with ‘narrowed’ hubs to counteract this effect and even some with 2 kilos of lead under the inner tube to get a stable platform.

I can’t remember who but someone has already widened their Coker hub.

Leo White, Cheltenham

3

Chris Reeder made a wider hub for his Coker.

4

By oscillation, do you mean side to side (toward the pedals), or orbital (in the direction of rotation)?

I’m really interested in getting a Coker, and I’ve been checking through all the forum posts I can find on them. A couple of people have said that the rims can’t be trued… is this true?

I think that higher flanges on the hub (I think this is what you mean by “a wider hub”) would make the wheel stiffer. I haven’t ridden a Coker, but on bicycles, this is generally the case; lower hub flanges make a more flexible, shock-absorbing, bump-forgiving wheel, while higher flanges give you a stiffer, and perhaps stronger rim.

I don’t know whether there’s an important relation between hub flange height and crank length… On second thought, I guess that rotational flex of the spokes (oscillation?) could depend on the relation of how much power you can deliver to the pedals (via the cranks) versus the length (and thus, flex) of the spokes.

Has anybody had a Coker wheel fail on (I mean under) them?

5

By wider it is more distance between the flanges so your feet actually end up farther apart (larger Q factor).

6

RE: Wider hubs?

> So what I envisage is a Coker with the hub maybe half as wide
> again, and forks suitably spaced to accommodate it, producing a
> ride with all the benefits of the big wheel, but with more
> structural stability. What does anyone else think?

I’m sure everyone else thinks the idea is great. Leo White pointed out how
the advantage of a narrow hub, in promoting a straighter line (less wobble).
But this has to be weighed against the risk of a wheel failure due to it’s
being too narrow.

On my big wheel (45.5"), I think it’s about 6" or more between the hub
flanges. This makes it more proportionate to smaller wheels. I’ve never had
a problem with it, but I also haven’t put zillions of miles on in the 20
years I’ve had it.

The Coker hub is Reeeel narrow, and I’d lean more toward doubling the
distance between the flanges, at a minimum.

But here’s the main problem. The big reason for the Coker’s success,
regardless of what anyone else says, is price. At its low price, basically
anyone can have one. To have a real nice one, with specialized versions of
hub and frame, would most likely double the price.

Several of the European Unicycle Tour riders had special frames on their
Cokers, made by Paul Wyganowski. These were hand made, so they were probably
pretty expensive. Something mass-produced would be cheaper, but only if made
in large quantities, beyond what the market can probably support.

I don’t remember what happened with the rim project someone was working on,
to get an alternative to the Coker’s rims.

Since the Coker is essentially a Semcycle XL with a giant wheel, to make a
higher-end version would probably be to upgrade most of the components,
working from the original (not upgraded) tire. New rim, new hub, better
frame, better seat, and some sort of handle/brake & computer mount/rack
system to attach all your stuff to.

Now how much would you pay? There’s the rub. The more expensive it gets, the
less people will buy it. That explains the Coker success story. When they
came out, I thought they wouldn’t hold up. But they do! They’re not perfect,
but it’s a lot of unicycle for the money.

Looks like the next big breakthrough will be the new unicycle from Norco.
Quality parts, and design input from a quality unicyclist, at around $400
(CA or US?)! I can’t wait to see one. I wonder how they will be sold in the
US, as Norcos seem to only be found in Canada?

Stay on top,
John Foss, the Uni-Cyclone
jfoss@unicycling.com

Mind where you grind

7

Oh. Wider axels/hubs. Doh! Now I get it!

I was thinking of the other kind of spoke parallelity :roll_eyes: … the angle relationship between spokes, that is, as they cross each other…
Now that I’ve got that straight, does the existing Coker frame allow for a wider hub? I’m guessing “not”.

I live in Japan, and my plan/hope/desire is to pick up a Coker on my next visit back to the States this Fall, and bring it back here, and hopefully get competent enough on it to use it to commute my sqidgy butt to work… Since I won’t be able to get the kind of service that Coker owners in the States can get, I’m thinking of getting everything I need to customize it to a daily-use dependability before I get on the plane to come back here. Everybody sings the praises of this uni, but at the same time, I keep seeing little criticisms… maybe these are just standard idealistic gearhead frettings (I’m a gearhead, too), but I’d appreciate any accounts of real trouble from Coker riders. I know, this ain’t Consumer Reports. Should I be concerned, or not?

8

Re: Wider hubs?

sendhair wrote:
> I’m really interested in getting a Coker, and I’ve been checking through
> all the forum posts I can find on them. A couple of people have said
> that the rims can’t be trued… is this true?

The wheel will be far from true when it arrives, and there’s no way it’ll go
in a jig. But it’s quite possible to true it in the frame, with patience.

–
Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny )
Recumbent cycle page: http://www.speedy5.freeserve.co.uk/recumbents/
“I don’t think proofreading is adequate. All posts should be waxed and
buffed. Then they should wear little tuxedos.” - Greg Harper on usenet

9

Re: Wider hubs?

>The wheel will be far from true when it arrives,

Not necessarily, John Drummond and John Kovachi are very cool about checking
tension and truing if you ask them. Ask them.

David Maxfield
Bainbridge Island, WA

10

Re: Wider hubs?

A Wyganowski Coker frame runs about $350.

Many of us have improved the Coker wheel slightly by rebuilding it around a
Suzue hub. It’s not much longer, but a bit.

The Coker frame is a real noodle. I bet you could use a longer hub without much
trouble.

The big improvement IMHO would be a better rim. John at Unicycle.com is working
on this. He had a false start, but is still working to bring one to market.

Despite all these problems, the Coker is magnificent–but it’s a road machine.
Handle it with some care. Going down curbs/kerbs is fine. Going up them isn’t.

David Maxfield
Bainbridge Island, WA

11

Here is a link to the EUT website and the custom coker info.
http://www.outtech.com/Unicycle/EUT/Coker/index.htm
The hubs were upgraded to Suzue and the frames are chromoly.

Over 3,000 miles on mine in the last year and it’s going strong.
http://www.outtech.com/Unicycle/EUT/Photos/pages/Day%2023%20-%20Barcelona%20Finish%20-%20Scot%20-%20Andy’s.htm

I rode this uni around Lake Tahoe almost two weeks ago. It is the ultimate touring unicycle. The seat will be upgraded to a leather airseat before I ride from San Francisco to Los Angeles in Sept. as part of the California Coast Classic ride for Arthritis.

12

Thanks to everyone who posted details about Cokers! It’s all very helpful and interesting. Are Wyganowski Coker frames stocked by any vendors, or are they built-to-order only?

13

Hello,

I own Chris Reeder’s modified Coker. I have put a lot of miles on both a widened hub and the narrow stock hub. Besides being stronger, I prefer the widened hub for several other reasons:

• Freemounting. I find it significantly easier to mount my widened Coker. I have not put a lot of consideration into why this is, but the extra leverage seems to help me get straightened out and going.
• Turning. I can turn tighter and more smoothly on my widened Coker. Here again I think the extra leverage helps. And no, despite my pedals being farther out I have never leaned over enough to have a pedal touch the ground. I can do this on a 24” wheel with 5.5” cranks.
• Wheel wobble. I don’t have much of a problem with this, even on a wide hub. Years of road bicycling have given me a silky smooth pedal stroke. I think the ability to pedal smoothly and evenly makes a bigger difference than the distance between your pedals does. Three-time Tour de France winner Greg LeMond first gave this tip in 1985, and it’s just as helpful today: When you pull your foot through the bottom of the stroke, imagine you’re scraping mud off your shoe. This will help you pull your foot through smoothly with added power.

I took a few photos of my Coker with the widened hub. They can be found here:

http://www.public.iastate.edu/~gbarnes/coker/

To see the wide hub compared to the stock hub, check out:

Also,

Wheel truing on a Coker is definitely not impossible. I’ve seen a wheel go from almost hitting the frame to true in a matter of minutes.

14

Can the Coker be upgraded at Unicycle.com (for a fee) before shipping? That’d be swell. Who the hell stocks 4 foot long spokes? (that length is exagerated)

15

I just happened to take a glance at Unicycle.com’s site tonight, and guess what? They’re now offering an upgraded Coker! It wasn’t on their page a day or two ago… Not a lot of detail in their online catalog, but they’ve upgraded the wheel (hand-built) and hub (but they don’t say how wide), and you can get it with an Odyssey V-brake (but they don’t mention how it’s attached), and a choice of saddles. Here’s the link: http://www.unicycle.com/shopping/shopexd.asp?id=568

Either they read your mind, or they read your last post, Sofa!

16

NEW ALLOY COKER RIM !!!

http://www.unicycle.com/shopping/shopexd.asp?id=569

Wonder what the shipping costs would be …

Leo White, Cheltenham UK

17

… Yeah, me too. The online shipping-cost calculator doesn’t recognize “Japan” when I choose it on the drop-down menu. That’s why I’m waiting 'til I go back to the States to get a Coker. Unfortunately, the “World-Wide Web” doesn’t allow for the transport of realia, and many vendors don’t want to bother with overseas sales.