I blew out my tubeless Coker tyre!

I wanted to see what it would feel like to ride on my Coker with the tyre at 50PSI, so I pumped it up merrily. Within seconds of taking the pump off the valve there was a very loud bang and the tyre had blown itself off the rim! My ears are still ringing from the bang. The tyre bead now seems permanently warped out of round, so it seems unlikely that it’ll be a functional tyre again, tubeless or tubed. A pity coz I reckon it had another 1000km of tread left on it easily. Also a pity coz original Coker tyres are very hard to get hold of in NZ.

Looks like no more SINZ tour training rides til I get a new tyre, or build up my Schlumpf.

Some pics:



Ouch! But I like the TA tyre better anyways. :stuck_out_tongue:

I just noticed this on the UDC USA web site

Could it be that you have one of the smaller Airfoil rims that is only compatible with the TA tyre?

I had no idea that the Airfoil rims were coming in different sizes now. What’s up with that? I’m so out of the loop.

Yep, I’ll probably end up with a Wheel TA tyre as a replacement. A bit annoying because its a heavier tyre and not so good for offroad (so I’ve read).

I doubt that my Airfoil rim is one of these X-marked smaller ones - I’ve had it for nearly four years and the only tyre I’ve ever had on it is a Coker tyre.

Don’t worry about the weight. Just ride it lots. It will wear down to be about the same weight as a Coker tyre by the time the SINZ tour rolls around. :sunglasses:

I like the handling of the TA tyre better. It handles road crown and off-camber corners better than the Coker tyre. I’m not sure how it will be once it is worn down, but while in the newish condition it is great. I haven’t had any problems with XC offroad riding with the TA. I haven’t tried it in wet or slippery conditions, but for forest dirt and sandy dirt it has done fine.

In this case, JC, there really isn’t a loop to be in, as it’s both fast-breaking news, and poorly communicated news. I know of it only because I’m living it, via the following scenario:

–I talk to _____(not Amy) at UDC, who tells me that any UDC Nimbus 36’ orders will ship the very next day.
–I order a new Nimbus 36" online…everything seems to be fine, no Warnings
–Two days later, UDC sends me a mail saying my UDC Nimbus 36 has been handed over to UPS, and I’ll hear from them soon.
–Two days later, I do in fact hear from UPS. They tell me that the order they were told to pick up has been cancelled…by UDC.
–Thinking “Okay, WTF is this all about?”, I call UDC and get Amy. She tells me that the cancellation is due to one of their employees mistakenly creating ship orders for a bunch of orders that in fact were not ready to be shipped. So they had to cancel them. My order is not ready to be shipped because they don’t yet have the 36" wheel builds back from Kovachi Wheels, which has been enjoying a Thanksgiving break from wheel-building, even though we’re now near the end of the first week of December.
–In passing, seemingly harmless, Amy also lets slide that the current Airfoil rims they’ve received don’t in fact work with the Coker tires, but never mind about that because the TA tire is the one specified on the web site and it’s a darn fine tire. I think to myself–and say to her–that for the kind of money being paid here, shouldn’t the best 36" rim on the market hold both of the available 36" tires? When you’re “spending up” for a best in class setup, shouldn’t you be able to count on that?
–Amy’s response was basically “Well, this is what we recieved from the rim-maker, and we’re not sure he’ll ever do another batch, so this is what we have.”

In other words, “Our supplier is incompetent, but rather than challenge that or assert our quality standards as a buyer and reject their defective batch, or do ANYTHING to support our customers, we’re just going to let their incompetence ride and pass the defects on to the group most important to our long-term survival, our customers. So what if they have spare Coker tires hanging in their garage…they just need to learn to love the TA, and the TA only. And that’s fine, because the TA will NEVER go out of business, so the customer will NEVER be stuck with a totally useless rim hanging in their garage right next to their totally useless Coker tire, both of which were purchased–coincidentally–from Unicycle.com. This whole concept of interoperability is over-rated.”

But frankly, given the endless series of mistakes which has always been the UDC (in the US) business model, I don’t know whether I really believe the Coker tire won’t fit. It could just be incompetent shop hands. I want to move to Europe for an upgrade in competence.

JC: Since I have one of these defects arriving in the next week (if Kovachi is done with his Turkey Dinner)–and I have a new Coker tire on hand–I’d propose you and I run the thing through the rigorous “Black Butte Porter” testing regimen. Let’s see if we can get a Coker tire mounted and inflated above 30 psi (the point at which all the UDC tests failed), so we can provide some neutral feedback to the community. I’m pissed now, but am willing to invest some time in the spirit of journalistic integrity. We can run tests up until Christmas eve, at which point I need to have a functional 36" to stash under the tree. The children should not suffer for the incompetence of adults.

The TA is not good on wet mud, I got thrown off on my local limestone cycle route due to a fairly small amount of mud covering the surface (and in to the only puddle on the entire 12 mile route incidently). OK now I’m no great cokeur but still, I was riding in a straight line at about 13mph on the flat and the tyre just shot out to one side, I’ve since been very careful riding this section but even if i slow down and take it carefully it still feels sketchy. Next week I’ll ride the same seciton with a couple of guys on Coker tyres and report back how they found it.

Porters are always good. :slight_smile: We can do some tire experimentation.

Don’t worry about being stuck with Coker tires. If they don’t fit the new rim you can always sell the Coker tires that you have. They’ll sell.

This is strange. A recent batch of Airfoil rims was actually made slightly too big. They had to cut them, weld them back togther, and powdercoat them to fix the problem. Now this batch is slightly too small? This isn’t good.

If there are hints that this may be the last batch of Airfoil rims then I hope that Kris Holm or someone is going to make a quality 36" rim. But if the rim changes the spoke lengths are also going to change. A fortunate coincidence with the Airfoil rim is that you could use the standard length Coker spokes with the Airfoil just by switching to a 4 cross instead of a 3 cross. If the rim changes to another supplier we’ll end up needing custom length spokes. This isn’t good.

I’ve had the Coker tire slide out sideways one me on a wet boardwalk. That UPD put a rip in my cycling tights. The Coker tire isn’t a sticky or grippy tire to begin with.

The big Coker wheel is also not all that stable in terms of tracking. Turning requires leaning and body english, both actions make it unstable on slippery surfaces. When pedaling hard the Coker wheel does a noticeable zig-zag “S” pattern as you pedal. That kind of action makes traction and stability worse on slippery surfaces. So the Coker isn’t good on slippery surfaces. You need to be careful when things get slippery to pedal smoothly (to avoid the “S” weaving) and stay as upright as possible when turning. Otherwise the Coker is going to dump you.

I think it is some problem between Coker tire company and UDC. We tok a phone to Coker and they have a lot 36*2,25 tire ready for shipping. No problem. Maybe UDC make the airfoil so they not want it to fit the tire from Coker? Anyway I only pump my tire up to 32 PSI who is the max pressure described on the tire wallside. If you get a blew out at 50 PSI I think you have to much pressure in your tire. Maybe it roll better, but not get so long life time. On my tire I think the tire get a bit flatter on the top if you ride a lot with high pressure.

Apparently happened to me too…although it was at the bike shop when they were installing my tubeless tyre. The bead blew off and looked a bit like your tyre. After that, I had to stick a tube in it. Unfortunately, that’s not a good idea because the bead then slipped shortly after and I watched the tube herniate out from underneath the bead and I started running away very very fast but it still exploded very loudly. Like a bomb going off. As I was in a small town in Australia called Toowomba on a Saturday evening, there was nowhere to get a new Coker tyre and I had to reinforce my replacement inner tube with duct tape and superglue to tyre to my rim. Luckily it held together for a 106km off-road bike race the next day.


p/s It seems that the tubeless system does make it more likely to blow out a tyre at high PSI’s- given that it’s happened to both me and Tony (although mine may have been a defective bead to start with).

But then, why would you want to run 50PSI when you’ve got tubeless? It’s so nice at low pressure! It will probably work fine with 10PSI.

toowoomba, ahahaha !

That’s really good to hear, John! I’m not a fan of highly cambered roads, so I’m interested to see how the Wheel TA tyre performs on these compared to the coker.

Unijuul- many riders use higher pressures in their coker tyres - 40 or 50PSI is not uncommon. 32PSI just feels horrible for road riding in my opinion. 40 PSI was nice, but I got greedy and wanted more - that was my undoing!

It appears that if you want a matching Airfoil and Coker tyre, you now have to get the Airfoil rim from the UK and the tyre from the US, as the UK has rims but no tyres and the US has tyres but smaller rims!

Gizmo - I think I’ll try www.rimskinz.com for my next tubeless 36" tyre. Kiwi made an’ all.

From what I’ve heard from UDC America, it’s not a great store, I don’t know how much shipping to the US would be but Municycle.com is a much better store, according to personal experience. My 36" airfoil rim is brilliant. However, you can’t blame them for the 36" rim coming in a slightly different size, if you want something done, do it yourself. Mail the company who makes them (Dave Stockton???) and ask him why he’s making the smaller rim, maybe there’s a good reason, maybe he’ll make the big ones instead if you ask.

I run the TA tire myself, people who call it a heavy tire are usually the ones who’ve never ridden it, Ken, Tony… because it’s slick I believe it’s a much better ride, even though I’ve only ridden a coker tire once or twice at Unicon and only for a minute or so. A light version of the TA tire would be the best.

Tony, why did you blow up your tire? From what I know from you you’re not the kind of guy who pumps his tire up above the max PSI just to see it explode :wink:



i’m pretty sure its not Dave Stockton who makes the Airfoil rims. Some company in California, I’ve heard.

I wanted to try riding at a higher pressure simply to see what its like. I’ve been experimenting a lot with different handles, brake setups and seat heights, so why not try different tyre pressures in order to see what the optimum is?

The Wheel TA tyre is definitely a heavier tyre than the original Coker tyre - that is undeniable, but only by a few hundred grams. Generally rotating weight should be minimised to give a better ride. However, the only spare 36" tyres in NZ are Wheel TAs, so there’s not much choice for me!

I weight my old Coker tire (not wear completely down) and a new Coker tire. The old tire was 180 gram lighter than the new one. When I cyckled the worlds biggest mountain bike race this summer on Unicycle, it was a big difference on a old Coker tire compared to a new one. Nearly 200g lighter tire at the outmoust of the wheel (biggest radius) is a complete different and lighter in the big climbs.

So the next summer I use new Coker tire on the tarmac in the spring to get them wear down some 180 gram, ready for use in big climbs at grawel later on the summer.

I’ve not had the chance to ride the Coker tyre, but I’ve found that TA tyre to be a very pleasant ride. It seems to handle cambers much better than my 29er Big Apple, it’s smooth, it’s silent, and it seems quite grippy - so long as you’re not on slippery surfaces. I sprained my ankle quite badly riding it on slippery mud.

Since Roger, one of the UK’s top distance riders, is basically leading UDC’s R&D stuff, developing the new products like the Touring Handle and 36" frame, it wouldn’t surprise me if Roger decided to fill the gap that Airfoil would be leaving by stopping production. Might not be for a long time, but I would have thought that eventually (even if it is purely as a cost-cutting exercise, Airfoils are very expensive anywhere except America) UDC might have an own-brand pro-rider 36" rim.


UDC is very tight-lipped about just who the airfoil rim manufacturer is. Obviously it is the same manufacturer that makes Arrow brand bmx rims, which have the exact same profile dimensions. They also make some Sun Ringle rims, like the MTX: http://www.sun-ringle.com/2006/mtbrims.jpg which sure looks like the airfoil to me, only in the mountain sizes. But alas, UDC is protecting them. Right you are Tom!

We have been working on a new double wall aluminium rim for the 36" unicycles for quite some time. It is as Richard says a long term plan…

It is appearing to be quite a hard nut to crack as the rim is bigger than most rim manufactures standard pinning/rolling jigs. So would require a relatively large outlay for a relatively small production run. We do have a couple of leads that we are working on. Cheaper welded steel rims are reletively easy to find.


Upset about new Airfoil rim

I am so sorry to hear about your blow-out.

Sorry to thread-jack but I can’t believe this about the Airfoil rim. I just ordered a tire from Coker over the weekend and was looking forward to assemble my own 36er. I wanted to support the coker company in at least a small way and I like the button tread pattern.

I didn’t buy the rim, spokes or hub yet. I also noticed the absence of any airfoil rim from the Bedford pricelist. Now what do I do? Send the tire back back and plan on using a new airfoil rim with the TA?

What about an old steel rim? Is it even worth considering assembling a steel rim with SS spokes and decent hub? That way, I could retain the flexibility to use either the Coker or TA tire. Or is that totally ridiculous?