Tubeless Coker

[GizmoDuck]

Ok- I've now done about 160km on my new tubeless Coker. It's great!

I was most impressed with Stan from Stans no-tubes who emailed me back personally. Stan makes the most popular tubeless kit for mountainbikes. He also made me a custom 36" rim strip for my Coker. They sent my package from the US to NZ- I got it within 10 days of placing my order.
http://www.no-tubes.com

I can't tell you much about the conversion itself, since I left my bike mechanic to do it. It was pretty straigtforward apparently. The 36" rim strip goes around the rim and the tyre goes on top. Then it's a couple of scoops of Stans sealant to seal up any holes. Apparently it was also holding air pretty well even before the sealant was put in. It would have been nice to have tried it without any sealant in there. But anyway, Blair (the mechanic) chucked in about 3 scoops of sealant.

My main reason for the conversion was to lighten the wheel. All up it saved about 200g.
A Coker inner tube weights 480-500g
The 36" rim strip (120g) and 3 scoops sealang (3x60g=180g).

When you consider the fact that this is rotating weight right at furthest point on your wheel, it feels quite significant. I'd previously converted my standard Coker Spokes (600g) to much thinner Unicycle Factory Stainless Spokes (don't have the weight- does anyone know?). I estimate this saved about 200g. So in total the Coker wheel is about 400g lighter after both conversions.

Well- the main thing you notice with the wheel is how lively it feels. Although it's not as big a jump as dropping all 400g at once, it still felt faster than just having the Stainless steel spoke conversion alone. It accelerates much faster and, more significantly, it seems to decelerate faster. I dont' use brakes on my coker, yet I was able to slow from about 30km/h to a stop (with 102mm cranks) in just a few metres. With less momentum- the tubeless/SS Coker seemed to track around corners in a tighter circle also.

I think some users on this forum questioned the loss of flywheel effect a while back. Basically, a Coker Wheel is so heavy anyway that you can afford to lose a lot of it before it feels as jittery as a 28'er. You can compensate by using shorter cranks, which is in fact the best thing about this. It's like moving up a gear- from Tubed to Tubeless is like going from 125mm cranks to 110mm cranks. Once you factor in the SS conversion and a stiff carbon seat you can almost ride 100mm cranks with the same ease as 125mm cranks on the standard Coker.

Off-road is probably where the tubeless Coker really shines. Without the fear of pinch flats (which you hardly ever get on a Coker anyway, but still), you can lower the pressure right down for better traction. Even at the same pressure, I think it rides nicer than a tubed Coker. The tyre is more compliant as there is no friction between the tyre and an inner tube. This thing hums on gravel.

There is another option of lightening the Coker wheel, which I'm hoping Tony Melton will try this week so that I can compare the two. That is to use a 29'er inner tube in a Coker- you'd be surprised how much it stretches. This should probably save even more weight than the Coker conversion, especially if your bike mechanic chucks in three scoops of sealant.

Anyway, I think this is the way Cokering should go. It's still a pretty heavy wheel so any method of lightening it is a good thing!


Ken Looi

[nathan]

Thanks for the writeup Ken. I may give this a try but will let you be the pioneer for a while. Let's see if it holds air over a period of several weeks - also that you have no trouble offroad. Sounds great though. I would happily give up some of the flywheel effect!

---Nathan

[john_childs]

Any info from Blair (the mechanic) about how hard it was to get the Coker tire back on? The new rim strip will be pretty thick which could end up making it very difficult to install, and later remove, the tire.

Using a 29er tube sounds interesting -- If it works.
The Coker tube is heavy. As a bonus a 29er tube is also less expensive.

Have Tony try the Rox Ultralight Rim Strip along with the 29er tube. The Rox rim strip could save maybe 30g or so. As a bonus the Rox rim strip makes it easier to install the Coker tire.

[TonyMelton]

I can't wait to try out your souped up Diet Coker at the Day-Nighter, Ken!

I just had my coker rebuilt with a widened hub and improved Magura brake mounts. (It now my 'Dietless Coker'.) In the process of rebuilding the wheel Johnnie Foster, my bike builder, discovered the joys of taking off the Coker tyre. He replaced the rim tape with a good quality bike one, I don't know which type, but it looks shiny and slippery. Nonetheless, when I tried to take the stock inner tube out on Friday it was very difficult - tyre lever breakingly difficult. I didn't manage to even budge the tyre. Maybe I need to try JC's toe strap method.

I wonder whether using a 28" inner rather than a 29" would make any appreciable difference. When an inner is stretched that much its going to be pretty thin anyway. I have a spare 28" tube on hand, but no 29" tube.

I think Dirtsurfer pioneered the tubeless Coker. Can you give us a report on how your tyre is holding up, Dirtsurfer?


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[Dirtsurfer]

Since December, I think I hooked up the pump to it three or four times (usually needing only one pump and added 1 'scoop' once). I will soon be replacing the tire (worn out, no flats) and checking the rim for true and tension. I have no experience with it off road, so I can't help you there. As for the rim strip thickness, when I installed the tire I'm using now, it was flat as a pancake. It would not inflate because the bead would not make contact with the rim strip properly. A foam tape had to be used to support the center of the rim strip. If the mechanic didn't have to use a foam tape, it wouldn't be any different mounting the tire with or without the strip. The foam tape increases the difficulty of the installation. Maybe having the tire inflated with a tube for awhile to give it shape, you could bypass using the foam tape.

[GizmoDuck]

John,
The inner rim strip is as thin as a regular rim strip- just wider so that it covers the whole width of the rim. It also has a valve stem sticking through it to allow you to pump up the tyre. you can see them on Stans no-tubes website (link above).

Dirtsurfer,
I don't think Blair needed to use a foam strip- I can't seem to visualise your foam strip- does it go over the rim strip? I guess my Coker tyre was already the right shape after being inflated with a tube previously.

You really got to try the tubeless Coker off-road. It's just magic. Especially tight twisty singletrack and gravel. I was going so fast it was scary.

Tony,
Blair is usually grumpy after working on my Coker- probably because he is the only one that can get the Coker tyre on the rim. It won't be any harder to get a tubeless tyre on compared to a tubed tyre- in fact it should be easier because you don't need to worry about pinching the tube with your tyre levers.

Nathan,
There was no appreciable air leak over the two days and 160km I rode. Although I had to let out quite a lot of pressure when I rode it on gravel. Will let you know in a few weeks how it holds up. It should be more puncture resistant than a tubed Coker- the Stans sealant seals up small holes and there is no risk of pinch flatting.

Ken

[GizmoDuck]

Originally posted by Dirtsurfer
It would not inflate because the bead would not make contact with the rim strip properly. A foam tape had to be used to support the center of the rim strip. If the mechanic didn't have to use a foam tape, it wouldn't be any different mounting the tire with or without the strip. The foam tape increases the difficulty of the installation. Maybe having the tire inflated with a tube for awhile to give it shape, you could bypass using the foam tape.

Actually, I think maybe your rim strip isn't wide enough- do you remember the width you ordered?

[ChangingLINKS.com]

Originally posted by GizmoDuck
There was no appreciable air leak over the two days and 160km I rode. Although I had to let out quite a lot of pressure when I rode it on gravel. Will let you know in a few weeks how it holds up. It should be more puncture resistant than a tubed Coker- the Stans sealant seals up small holes and there is no risk of pinch flatting.

Ken

I am sure that the Stans will hold up to your expectations - you may lose a bit of air - but it will be insignificant.

However, I found a concern with the Stans kit is lateral pressure. I.E. if you fishtail on a mtnbke or sidehop on a uni (causing the tire to start to slide off) you *can* lose bursts of air. That concern made me ride differently - I could trek off-trail more (without worry of thorns) however, overall, I rode less agressively for fear I would lose 4-8 pounds.

Also, sharp rocks can take their toll. On several occassions, a rock cut my tire between the knobs and I lost ALL pressure (the hole was simply too big). I solved that "buy bying" a tire with a continuous raise tread.

One day, I had the "best of times and the worst of times" with Stans. I lost ALL pressure from my back wheel from a sharp rock. I walked/rode a mile and ended up pulling 40 thorns from my front tire (with no significant loss of pressure). I walked 2 more miles to a gas station, "borrowed" a quarter and used the air to re-inflate the back wheel. I rode home 5 miles without further trouble.

Overall, I felt is was the best upgrade that I made. I have not gone with Stan's on my municycle - but that's only because I have not had the same trouble with flats. For some reason, I have been able to pull thorns out of the tire and luck/thickness has been sufficient.

[GizmoDuck]

Originally posted by ChangingLINKS.com


However, I found a concern with the Stans kit is lateral pressure. I.E. if you fishtail on a mtnbke or sidehop on a uni (causing the tire to start to slide off) you *can* lose bursts of air. That concern made me ride differently - I could trek off-trail more (without worry of thorns) however, overall, I rode less agressively for fear I would lose 4-8 pounds.

Also, sharp rocks can take their toll. On several occassions, a rock cut my tire between the knobs and I lost ALL pressure (the hole was simply too big). I solved that "buy bying" a tire with a continuous raise tread.

Mr Links,

I figure that if a rock is big enough to make a hole in the Stans kit- it's big enough to rip a hole with your regular tyre/tube system. Either way is a walk home. You might be able to patch the tube, but likewise you could bring along a spare inner tube to stick in the tubeless system if you get a puncture. If you can get the Coker tyre on/off that is.

I've not thought about side-ways hopping- I don't think it's major issue on the Coker. I guess on a MUNi at low pressure you might need to be more careful.

Haha- what are you doing riding through thorns like that

Ken

[Dirtsurfer]

The foam tape goes over the strapping tape and beneath the rim strip. I did not have to do this on my MUni, which is also tubeless. Nor have I had any "burbing" of the tire on either. Bikes are a different story, turning at higher speeds.

[ChangingLINKS.com]

Nor have I had any "burbing" of the tire on either. Bikes are a different story, turning at higher speeds.

That's really good to hear. I wonder if it will work just as well with trials.
Air pressure may be a solution to lateral movement from hopping.

Haha- what are you doing riding through thorns like that?

Here there are bushes of thorns that can even be mowed flat (hidden in the grass). I usually don't see them until after they've struck.
Come to think of it, i have never had the "sharp rock" problem on my municycle - perhaps that is more an issue of speed.


I like the stan's and would use it if I got more flats - or if I didn't change my tire so much (stan's is definately messy and expensive {10.50/bottle or so}).
For now, I could get away with just packing a small can of "fix a flat."

[TonyMelton]

I have successfully replaced my stock Coker inner with a 29" inner tube. It seems fine for now, but I have only ridden it a kilometre or less. I just hope that it passes the 12 hour torture test of the Day-Night Thriller tomorrow! Fingers crossed!


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[nathan]

How hard was it to stretch it?

[GizmoDuck]

Originally posted by TonyMelton
I have successfully replaced my stock Coker inner with a 29" inner tube. It seems fine for now, but I have only ridden it a kilometre or less. I just hope that it passes the 12 hour torture test of the Day-Night Thriller tomorrow! Fingers crossed!


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Whoopee! I can't wait to try it! Did you weigh the 29'er inner tube? I think you probably saved more than I did with the tubeless conversion- probably about 300g?

You may need to run slightly higher pressures- I think it will be slightly more vulnearable to snakebite punctures.

Ken

[TonyMelton]

The 29" inner was not hard to stretch to fit the Airfoil rim at all. Just pump it up while not inside the tyre and without anything to restrict it it will keep expanding (until it bursts!).

I didn't weigh the 29" inner, but I've read that the type I got (Quality Parts)weighs 225g. I got the thickest one I could, because I knew it would be stretched and consequently thinner thus exposing it to possible pinch flats. There are other lighter, thinner 29" inners available. My stock Coker inner weighs 503.5g without the valve cap. Looks like I've saved at least 250g of rotating mass! Nice one.


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