Coker: Steel Rim vs. Aluminum Rim

I finally got my 2nd Coker built with my Airfoil rim on Saturday and had a chance to get a little bit of time riding it yesterday and today.

Wow! Having ridden with the stock rim for three years, riding with the Airfoil rim made the Coker handle like a completely different machine! I can’t say that I like the Airfoil rim better or worse… though it is certainly stronger – so it is better in that regard.

While the Airfoil rim makes the Coker extremely nimble and responsive, the lighter weight rim also makes it less stable. On the one hand it was nice to be able to maneuver and accelerate/decelerate with such little effort, but at the same time it was easy to over control when making high speed aggressive turns.

The steel rim feels significantly more stable in aggressive turns due to its heavier weight and flywheel effect – you can just plan your entry, dive it to the desired lean angle, and essentially hold on for the ride! The aluminum rim Coker felt more skittish in aggressive turns and didn’t give you the same feel of locking into the turn as you get with the steel rim Coker. The greater weight/stability of the steel rim Coker seemed like it could be preferable in various specific riding circumstances. On the other hand, it was awesome to be able to plow up decently high curbs like they were nothing with my Airfoil Coker and hardly feel the impact! I can’t wait to do some drops that I wouldn’t attempt with my steel rim, too.

I read that some Cokers now come with a stock aluminum rim. Is the steel rim still available? Does anyone know if Coker is planning to phase out the steel rim and only use aluminum rims?

I just wanted to point out that the stock steel rim offers a specific type of handling that you won’t get from the aluminum rim which, in my opinion, is a real nice option to have at your disposal. I’m psyched to be able to have access to the aluminum Airfoil rim, which is incredible… but I’d hate to see steel rims disappear from the market.

You could always add weight to the Airfoil rim by taping or gluing some lead strips to the rim. Maybe crimping a lead fishing weight to each spoke.

I suspect you’ll get used to the change. You may even decide to try a 29er tube to save even more weight. :slight_smile:

Just think about how much gas money you’ll save not driving the heavy coker around NJ

I’d give you my old rim but it’s too much fun tacoing it with my bare hands…

We have been doing some checking and just for the record. The Qu-Ax rim is not aluminium, but is steel with a brushed aluminium look. We don’t have any of the Cokers here so I can not check - but my guess is that they are the same.

Tacoing the steel rims. I would have said that the majority of the times that the problem with the steel rims that taco is that they are over tensioned or dramatically under-tensioned. Spoke tension is critical on these larger wheels and if you are used to tensioning normal wheels then you will over tension the longer spokes… use a spoke tensioner if you are not sure. The other problem is people riding with too low an air pressure and this then causes the tyre to squeal on the ground and just twists the rim into a taco shape. They do flex in a way that the aero rims don’t; but for normal riding and if they are built correctly they are perfect for normal riding. I rode over 4000 miles on my standard rim before I changed it for an aero rim, this included a Polaris Challenge and several 24hour mountain bike races and I don’t remember ever tacoing my rim.

Roger

Dave that’s a hoot & a half!! You may build the world’s strongest coker wheel, but you don’t have to be the world’s strongest man to taco a wheel based on mid-20th century technology! Hopefully Arrow Racing in Oregon is making more Airfoil rims as we speak.

While the Airfoil rim is much stronger than the steel rim (and the Stockton wheel is obviously MUCH stronger than the stock Airfoil wheelset), I truly believe that the stable handling characteristics (even with it’s mid-20th century technology) of the steel rim are EXTREMELY desirable in various situations.

A decent comparison would be the way a heavier motorcycle holds the road and feels more stable than a lighter bike.

While many Coker riders on the forum may be trying everything they can think of to reduce the weight of their machine - which I will probably do, too - I will always want to have a nice, heavy, stable Coker as well.

If you haven’t already been riding on an Airfoil rim and you want a good way to notice the difference, just try some one-foot riding on a steel rim Coker and an Airfoil rim Coker. I can ride the steel rim Coker with one foot nearly endlessly, turning in any direction, with ease. One-foot riding on the Airfoil rim requires substantialy more effort. Of course, it will require less effort with more practice, but I don’t think there is any denying the stability advantage of the heavier rim.

What is the weight difference between the stock steel and Airfoil rims? What is the weight of the tire and tube? I have always thought (it has always been part of my belief system) that most of the weight is in the tire and tube, not in the wheel. I’m wondering if what you experience is a vast difference in the wheel flexure, not a vast difference in the angular momentum.

I don’t know what the weight difference is between the stock steel rim and the Airfoil rim, but I’m real curious to find out! Just from lugging it around, it seems like the Airfoil rim is a decent amount lighter.

I assumed the difference in weight is due to the weight difference of the rims because my two Cokers are set up essentially identically, other than the rim (and a really worn out tire compared to a brand new one). I further speculated that the difference in handling was due to the difference in weight… but not being too knowledgable about physics (other than that related to aviation), I could certainly be wrong… and you may be correct.

Are you indicating that perhaps the greater flexure (I assume the steel rim has greater flexure) provides greater stability?

I assumed that the greater weight and flywheel effect was the main factor contributing to the greater stability… which seems to make a lot of sense to me.

I don’t know, that’s why I asked about the weight. There will be a big difference in the way a stiff wheel and a wonky wheel feel under the stresses to which you subject them (I have seen your videos). The steel rim will flex way more because it has such an inferior cross section.

An interesting concept. Of course the amount of flex in each wheel will have more to do with the build and current condition of the spokes than what the rim’s made out of.

My Coker wheel is super heavy. If it was lighter, I’m sure I could ride it to work faster. The only heavier wheel I have (I assume) is my 45" big wheel, but the Coker wheel is still pretty heavy.

If you ride Coker all the time, I can imagine being more attuned to the heaviness of the wheel. For me, I use the Coker mostly for work, and other unicycles for everything else. My next-most-common ride is probably my Wilder, which has a heavy Gazzalodi tire and Sun Doublewide rim. Even that’s heavy.

So where I can see extra weight being useful for a certain few moves you might do, in the long run I think even you will prefer a lighter wheel.

Thanks for this discussion about 36" rim and wheel weights. I am interested as I mull what to buy next.

Harper asked about the weight difference between Coker rim and Airfoil rim. I spotted these stats on uni dot com:

Coker 36-inch Rim * Weight: 3 lbs, 5.2 oz.

Airfoil 36-inch Rim * Weight: 2 lbs, 12.2 oz.

If these are accurate and the difference is 9 oz., I would think a long term Coker rider would immediately notice a very significant change.

When I removed the heavy Coker tube from my stock Coker and installed a 29" tube that was about 1/2 lb. lighter, I really noticed the weight drop.

Personally, I am excited to lighten my 36er again by going to the Airfoil and maybe even the lighter gauge stainless spokes.

Speaking of lightening up wheels, who’s gonna be the first to have an ultra light/ultra strong coker wheel using 16 or 18 guage aermet spokes. Aermet, after doing more research from the pedal design thread, would be able to be a strong enough spoke with around 1/3-1/2 the mass, along with less diameter. I mentioned the material offhand to a sailor, and he said he already knew about it from sailing. One of his ships uses aermet rigging cables–2,000lb operating capacity, coming from 1/16" line, INCLUDING VINYL CASING. Seriously, I’d like to see someone make a wheel with aermet spokes, just to see what the difference is. Titanium won’t work since the wheel will be too flexy.

Re: Coker: Steel Rim vs. Aluminum Rim

On Tue, 15 Mar 2005 16:26:47 -0600, “harper” wrote:

>What is the weight difference between the stock steel and Airfoil rims?
>What is the weight of the tire and tube?

Incidentally, I started a thread 8 days ago about just that. From what
U-Turn and John Childs posted, I inferred/averaged:

stock steel rim = 1860 g
airfoil rim = 1235 g
Coker tyre = 2000 g
Coker tube = 540 g

So the rim+tyre+tube is either 4400 g or 3775 g. Significant, but not
earth-shocking I think. Spokes will add to rotational inertia, so
assuming you use the same spokes in both cases, the relative
difference of using one rim or the other is somewhat smaller still.

Klaas Bil - Newsgroup Addict

people who unicycle are shyly exhibitionistic - GILD

Exact weight of steel rim without rim tape 1805
Exact weight of aero rim without rim tape 1232

Roger

One final and marginally insignificant point: the effective radius of the rim is a few cm less than the effective radius of the more massive tire and tube combination. This reduces the fractional moment of inertia of the rim with respect to the total moment of inertia of the assembly. The moment of inertia is actually in question here, not the mass.

Re: Coker: Steel Rim vs. Aluminum Rim

On Wed, 16 Mar 2005 04:12:05 -0600, “rogeratunicycledotcom” wrote:

>Exact weight of steel rim without rim tape 1805
>Exact weight of aero rim without rim tape 1232

One thing to keep in mind is individual variation. Dave of Surly MC
mentioned in another thread (Where to buy Large Marge) that the weight
of Large Marge rims may vary as much as 10%, although it will usually
stay within 5%. I can only assume that something similar holds for
other rims, such as Coker’s.

Klaas Bil - Newsgroup Addict

people who unicycle are shyly exhibitionistic - GILD

Now that I Have accumulated a bit more time on my Airfoil Coker riding in the Urban Jungle (NYC), I feel that my real world riding experience confirms Harper’s intuition.

While I had initiially attributed the difference in handling between the steel rim Coker and the Airfoil Coker primarily to the greater weight of the steel rim (and thus greater gyroscopic stability)… it seems quite likely that it is the greater flexure (as Harper pointed out) which is probably the more significant factor… at least when it comes to real aggressive turns.

The aggressive, steep banked turns I utilize developed out of necessity from riding through the streets of Manhattan. It is essentially the only option I have to save my butt in various emergency situations. Jumping off usually isn’t an option because I would be jumping straight into the car that’s about to cross my path just ahead of me… which would guarantee a really bad outcome!

When I attempt a real aggressive steep banked turn on the Airfoil rim… if the entry (speed, angle, smoothness) isn’t just perfect, it feels like the Airfoil Coker is bucking me off… and I get thrown! Plus, my entry speed has to be slower in order to achieve the same level of bank on the Airfoil Coker. Thus, if I’m going really fast on the Airfoil Coker and I have to dive it into an emergency u-turn… I’m probably going to be in trouble (hopefully the wheel would slide out into the car rather than my getting thrown into the car)!

Another thing that I have noticed on the Airfoil Coker sometimes (that is pretty weird) is a tendency of the machine to want to turn in the opposite direction of my turn when exiting a steep turn… never felt that happen on my steel-rim Coker.

I don’t see how the flexure of the steel rim would make it feel more stable when riding straight and level, 1-foot, etc., so I have to attribute this feeling of greater stability (compared to the aluminum rim) strictly to the weight. For riding in the Urban Jungle… where there are lots of pot holes, hard-to-see depressions, cracks, rocks, flapjacks from the annoying NYC mounted police, and plenty of other obstacles… I feel a LOT safer on my lumbering, good-ole steel rim! I may not be able to accelerate/deccelerate as fast… but deccelerating can’t save me in an emergency and turning can! So all you guys (and gals) can go nuts making your Coker’s lighter (and so, too, will I with my 'foil Coker, probably)… but just save your steel rims for me :smiley: !

PS: I’m simply pointing out what I feel are the benefits of the steel rim for a specific kind of riding in a congested urban environment. For many types of riding… especially riding that is going to subject your rim to heavy stresses (such as MUni), a strong, state-of-the-art rim/wheel is obviously MUCH preferable!

I’m curious how much of that is due to what your used to. If you had two years of riding the airfoil under your belt, would you feel the same way? Will you be able to attain the same level of confidence with the airfoil as you now have with the steel rim?

The reason I ask, is if I were to attempt any of the things I see you do on a steel rim I would be eating asphault. Same goes for the airfoil.:smiley:

PS What type of pedals do you use?

I’ve actually wondered about that myself quite a bit (how much is due to what I’m used to)… and as of right now I’m fairly convinced that it is more due to an actual difference in the handling of the equipment than my familiarity with it… though I’m sure I’ll get better as I get more familiar with the equipment through more riding time… but I don’t think I’ll EVER be as good (or at least as consistent) on the Airfoil Coker for certain maneuvers (steep banked turns) and certain types of riding… but I could be wrong - only time will tell, I suppose.

Though it doesn’t happen too frequently… I have eaten quite a bit of asphault since getting my Coker… and I expect that probably won’t change anytime soon :D!

I use PRIMO (platform) pedals. Actually it looks like it’s spelled “PR1MO” with a “1” instead on an “I”. They are relatively light, pretty strong, fairly economically priced, and come in a nice assortment of colors. They come with back-up pins, though I have no idea how to put them in (they don’t look like the standard screw-type pin as other platform pedals have) because I never had to replace them. I like the logo on the pedal caps, too - it’s kinda cool - but I always lose the caps, anyway (gotta get in touch with the company and order like 20 extra caps, if possible!). Anyway, I like the pedals a lot… I have them on both of my Cokers.