Coker: Steel Rim vs. Aluminum Rim

I’m also wondering if the riding problems that you’re experiencing now are because you haven’t gotten tuned into the new, tight, sports car handling of the Airfoil rim. You’ve gotten so used to the much more forgiving handling of the steel rim that if you try riding it the same way , you end up over controlling with out realizing it. After all, you could always ride it that way before, and if this is such an incredible wheel, it should ride incredibly.

Once you get really comfortable on the Airfoil, you’ll probably find that you can do much more with it, including higher speed and steeper, banked turns.

The Airfoil Coker does ride incredibly… just differently. I do believe you are correct in regard to the handling as it pertains to how nimble and responsiveness the unicycle is with the Airfoil rim… so yes I will be able to transition from one turn into another quicker, for example… but I do believe that the greater flexure of the steel rim (as Harper pointed out) is a major factor that enables me to achieve the steep banked turns easily. Even if I can ultimately figure out how to achieve the same level of bank, just as aggressively (and with the same entry speed) with the stiffer Airfoil rim… do I really want to have to utilize the added effort and concentration to pull it off on the more high-performance, yet squirrely, Airfoil Coker? Especially since I’m riding in the City with lots of pot holes and eneven streets (and cars and pedestrians everywhere)… the added weight and stability of the heavier steel rim Coker is quite comforting.

No matter how accustomed I get to the Airfoil Coker, I think it will always be easier (and probably safer) to do steep banked turns on the heavier Coker.

Higher speeds, definitely. I’m not sure about the steeper, banked turns though… at least not from a decently fast entry speed, anyway.

36-inch rim “flexure”

Interesting discussion about rim flexure and the potential for it to vary significantly between Coker and Airfoil rims. I don’t doubt that the difference in rims is, at least, partly responsible. But, the subject has me thinking about the other possible elements that may affect flexure and your tight turns performance.

HUB - is your new hub the same as your old one? Same flange to flange distance and same flange diameter?

SPOKES - are your new spokes the same as the old ones?

WHEEL BUILD - is your new wheel build similar to the old as far as spoke tension?

FRAME - same frame on both new and old?

I am wondering if your experience of a radical performance difference between Coker rim and Airfoil rim might be exagerated by any of these other factors.

Re: 36-inch rim “flexure”

You are correct… it is definitely a combination of factors regarding the wheel. I have the wider hub with the Airfoil rim… and the spoke tension is much tighter, as well. The frame and everything else is the same (except for the tire being worn bald on my steel-rim Coker).

Re: Re: 36-inch rim “flexure”

This is probably the main reason for not settling on the new wheel and hence finding corners better on the old rim. The wider hub is definatly less good for speed, the foot position is unnaturally wide and reduces the ability to spin. It also gives you greater load to turn the wheel using foot pressure so making it feel more “responsive” on turns.

I think the wide hub on my unicycle took 1mph off my top cruising speed initially and it took me over 6 months to get back to anywhere near it. This being said it has produced a more nimble and versile machine because it is definately more manoeverable and better off road.


Re: Re: Re: 36-inch rim “flexure”

Having accumulated some more time on my Airfoil Coker… and comparing it to my steel rim (smaller hub) Coker, I am in complete agreement with your assessment, Roger.

Wow… this is a LOT more complex than I had realized - weight, flexure, hub width, etc. (I’m sure Harper can throw in a bunch of others)!

For speed, I prefer the steel rim over the Airfoil rim by a good margin. It definitely feels like I can really spin that steel rim a LOT better.

Though I had inititially thought I’d prefer the Airfoil rim for top speed due to it’s lighter weight, it turned out not to be the case at all. While it does accelerate and decelerate faster… that may be one of the reasons I like it less… being able to maintain a good constant speed more easily (over varying terrain) with the steel rim is quite nice.

The even more important factor, however, seems to be the lateral motion of the wheel. Though, as Roger pointed out, it is more responsive due, in part, to the wider hub… I think that greater responsiveness also causes greater lateral motion of the wheel. It seems like I can keep the wheel on my steel rim (small hub) Coker a lot straighter, a lot more easily than my Airfoil Coker with the wide hub.

Now if only it were possible to somehow engineer a small hub that offered the benefits of the big one!

I think that if you went cold turkey with the better wheel you’d find that your body adapted to the new dynamics, and that soon you’d look back with wonder at how you kept going with the old one. The stiffer wheel requires greater finesse, but the stock wheel is overwhelming that and the finesse get swallowed up.

In the same way I found it easier, when I was learning, to 1-foot on the trials than on the freestyle, especially outside on a rough asphault surface. The trials with a low psi and fat tire, absorbed a lot of my balance and pedal pressure crudeness. It took a lot more finesse to do the same thing on the freestyle with 80psi of pressure.

The real question about width when thinking about speed is not the width of the hub, but the Q factor that your body’s shape requires. One needs to match the Q of the setup to your hip width and leg configuration. The wider hub adds to the overall Q. Perhaps using cranks with less contribution to Q would help you adapt to the better wheel more quickly.

For some riders, the additional Q produced by the wider hub would make them ride faster, because of their hip and leg geometry.

You guys can take the fun out of everything!

I am waiting for a Dave Stockton wheel as I enjoy but curse my original wheel a few times a week. The weight and my freemounting ability are one thing, but what I worry about is all the creaking, flexing, being unable to true it and yes the original rim has done the taco with a guy (not me) of about 100kgs bunny hopping.

Metalurgically (nice word) speaking, steel is an alloy of carbon and iron, so not all alloys are other metals like aluminium. Steels of various alloys (% carbon) can be heat treated for toughness, hardness and tensile strength.

So…ooo, if weight is great, why doesn’t some company make a higher grade steel alloy rim that has the weight but can overcome all the other Coker problems. In other word, a strong steel rim. What about cromo etc.

I look forward to getting my Dave Stockton wheel and only then will I know what you are all talking about.