29er tube in coker help

I forgot to add that U-Turn’s web page on installing a 29er tube in a Coker includes a link to the Schwalbe North America web page where you can order the tube. AV 19 is the size that you want. AV is Schrader valve and 19 is the number for their 29er size (40/60-622/635). 622 is the rim diameter for a 700c rim and the 40/60 is the width.

hmm, okay, I think I do understand it now…yeah, it does seem like a pretty confusing topic q-: I think I’ll prolly order the Schwalbe tube John recommended…

Bontrager also make a 29" inner with a Schrader valve. I don’t know where you can get them from, though. (They aren’t available in NZ, anyways.)

Bontrager is owned by Trek now so I would guess that a bike shop that carries Trek bikes would be able to get the Bontrager 29er tube.

I didn’t know Bontrager made a 29er tube, and especially one with a Schrader valve. I went to one of the local Trek bike dealers asking about 29er tubes and they were clueless. I guess they didn’t realize Bontrager made them. Shopping around for a 29er tube can be an exercise in frustration. So many shops know nothing about 29ers.

Bike shops are useless for 29er parts.

Schwalbe do 700c 40-60mm, which is a really nice big tube.

IRC do a 29er tube, but I think in presta only. You could probably use it with washers, but it’d be a bit risky as they’re not such sturdy valves.


aaalright everybody. I did it.
bought the 29er tube, and stuck it in my Coker, but thus far haven’t had much of a chance to try it out yet. I have tried it out, and it’s AWESOME!! it turns so easily, and speeds up/slows down so easily…sweet.
but. for some reason, my rim now seems waaay out of true, vertically. as in I can feel it going up and down when I ride, and of course I can see it when I get off and spin the wheel.
is it possible that I bent the rim while pulling on it to get the tube on, and the tire on/off, etc.?

also. I was wondering, has anyone seemingly successfully install a 29er tube and ridden it for a short while, then have it pop while they’re on it? because that would suck. a lot. so I’m just wondering if that’s something I should worry about.

Your tire is probably not seated correctly in the rim. The bead of the tire needs to fit evenly all the way around the rim and on both sides of the rim. If the bead is not properly seated the tire can have a bump (almost like a flat spot) just like you describe.

Deflate the tire and then reinflate it to about 50 psi or so. Then let it sit for a bit. The tire will try to even out the pressure on it and will try to even out the bead all the way around. If that doesn’t work then deflate and try again. If that doesn’t work then get forceful with tire leves to even out the tire.

What I do now for the Coker is spray the bead of the tire and a bit of the sidewall with Silicone spray lubricant. That seems to help with installing the tire and also helps the tire to seat itself after being inflated.

Do you have the stock rim or Airfoil?

Also be careful with the rim strip or rim tape. It is very easy to peel away part of the rim tape and expose a few spoke holes while trying to install the tire. This is especially true with the Airfoil rim. After getting the tire installed, and before inflating it for the first time, you should stick a tire lever down the side of the tire and inspect the rim tape all the way around the tire and on both sides of the tire. Make sure the rim tape hasn’t folded over in any places or shifted over a bit. Make sure all the spoke holes are still covered. Every time I put a Coker tire on an Airfoil rim I have to make adjustments to the rim tape after the tire is installed.

I just helped tomblackwood put a 29er tube in his Airfoil Coker last night. Wasn’t too difficult at all. In fact it was one of the easiest tire installs I’ve done with the Airfoil rim. It was also the second time that I did the silicone spray treatment. Seemed to help a lot.

Yes, it is true. The Doctor made a house call. I tried to “help”, but in the end was extraneous. The rim-fighting challenge JC was hoping for just didn’t materialize. That aside, I learned a ton in the process, and as always JC rocks!

I should also note that this was my first tire change since purchasing my GB4 36 from U-Turn, and it happened at exactly 1,300 miles. The tire was bald but not quite down to the threads. In addition to a new Coker tire, I dumped the heavy Coker tube for a lighter Schwalbe 28" tube. After a 10 mile ride tonight, I have to say that the difference is dramatic. Felt squirrely at first, but almost everything is easier with the 28" tube. Mounting, idling, stopping, starting after a standing break, accelerating, and especially CLIMBING. Stuff I had to stand up for yesterday I stayed in the seat for today. Only areas it was tougher was gravel (marginally), sloped crowns, and steep decents with brake. On the downhills, a light feather touch on the Maguras was definitely more critical…less mass in the wheel to help roll it through the braking.


U-turn’s 29" installation instructions are great. Thank you for the help.

One suggestion for a one person installation, at step 5):
Tie the tire/tube/rim points at two anchor points (~180 degrees apart) to hold tube in place and continue to stretch the tube completely around the rim.

I wrapped short bungee cords around to anchor/hold things and then completing the tube stretch was easy.

(My mounting the second bead of the tire is another ongoing story.)

I just recently did my first Coker tire with 29er tube installation onto an Airfoil rim. I was going to resurrect this thread but then this thread was resurrected and now this one.

I got my Airfoil rim, TM Spokes, Sem nipples and UDC wide hub a while back. unisk8r laced it up and trued the wheelset. He sold me one of his Bontrager 27 x 1 3/8-1 3/4 / 700 x 35c-44c tubes that he uses in his wheels.

Pete suggested inflating the tube to pre-stretch it and then deflate it onto the rim. After doing that I placed the rim with tube inside the tire and worked the first bead on by hand. On the second side I experienced the same problem many described about that last 18”. Of course I didn’t search the for a before attempting installation, I finally ended up holding one of the tire levers down with my foot (rather than the rubber band method which would have been much smarter) and worked the other side of the bead with the other two levers, about an inch at at time. These were standard plastic tire levers and worked fine. After the tire was on I inflated it by floor pump to about 35 PSI but the bead wouldn’t seat. I got tired of the floor pump and resorted to the air compressor; it seated after a while at about 40 PSI.

The next problem I had was that the tire was down to about 20 PSI the next morning. I deflated the tire, checked for pinches, and re-inflated. After a day it was down to 20 PSI again. Looks like a slow leak that “seals” at 20 PSI. Rather than go through the hassle of another dismount & mount of the tire I thought to try some tire sealant. I didn’t realize they recommended 4-6 oz. for a tire the size of a Coker. There goes your weight savings. Instead I put only about 1-2 oz. in and spun the wheel for about ½ hour this morning (to kill time I read the paper and lurked on RSU). I pumped it up to 40 PSI and left for the Thanksgiving gluttony. Came home this evening and still at 40 PSI.

Now I can hardly wait for the frame to show up so I can ride the new wheel.

No tools Coker still applies (except for the choice of rim tape)… just did one a couple of days ago with a 29er tube. I’m not a he-man-type, so you guys with V-shapes and actual abs shouldn’t be having these troubles. Take your time and keep pushing the bead into the center channel.

Having failed my previous attempt with mounting 29 tube on my Coker, I’m getting the urge to try again. (I had the tube in, but could not get the tire on. LBS then mounted the tire with the original full size tube.)

Is there a difference between mounting a ‘Coker’ or a ‘TA’ tire on the airfoil rim. I know they both can be hard to mount but could it be that the TA tire (like I have) is more difficult to mount than the Coker tire?

Well, I just trashed all three of my 29" tubes (Schwalbe AV19, three more on the way) and I’m working with a Coker tire. I don’t know if the TA is harder, but the Coker sure isn’t easy. I don’t know how to be sure the lever isn’t pinching the tube once there isn’t room to get my fingers in there.

I’m not looking forward to getting a flat and having to do all this again, but I sure would like a lighter wheel for the Laos tour.

Now I’ve done a few 29er installs, mostly successful, and I have to say that doing it no-tools is really difficult and probably not worth the trouble.

I assume you are talking about the 2nd side of the tire. In this case, use more air in the tube. This makes it harder for the lever to grab the tube and more likely for the lever to slip past the tube where it belongs. It also makes it harder to get the tire into the center channel, but that’s a complication that we have to live with.

Scott Wallis also recommends talc all over the tube.

I discovered a trick that makes getting the Coker tire on an Airfoil rim really easy (well, much much easier). I’m using a 29er tube now in my JC Coker (Schwalbe tube).

I use fabric style rim tape. About 16mm width. Get the rim tape snug in the rim.

Then I use strapping tape over the rim tape. I cut the strapping tape to be wide enough to cover the bottom of the rim, pretty much from sidewall to sidewall.

The strapping tape is slippery and makes it much easier for the tire to slide down into the center channel of the rim while installing the tire. The big problem I have is the tire getting hung up on the edge of the rim tape. It will peel the rim tape off or just get hung up and not slide down into the center channel of the rim. The strapping tape solves that problem.

The strapping tape does not need to cover 100% of the circumference of the rim. I covered about 70% to 80% of the rim and that was plenty. I cut short strips a couple inches long so they would be easy to apply. Then went around the rim piece by piece.

Then a little Silicone spray lubricant around the bead area of the tire and follow U-Turn’s instructions for installing a 29er tube in a Coker. Oh, and talc on the tube helps too.

With the strapping tape over the rim tape it was really easy to install the tire. It felt like it would be completely possible to do it by hand with no tools. The thought of needing to repair a flat or replace a tube is no longer a scary thought.

Next time I take the tire off I’ll try to remember to take pictures of the strapping tape. The description should be explanatory enought, but pictures are worth 1000 words.

questions for jc

I use a fabric style rim tape that is the kind they use on mountain bike tires. i have to tape one on and they use part of another to get all the way around the rim. Is that the same kind you are talking about, John?

What is strapping tape? Clear-plastic tape used to tape up a cardboard box?

just found this:

and this:

is that what you use? that’s the kind with thread running through the tape. it’s easier to remove.

I use the MTB or road bike rim tape like Velox brand. It takes a little bit more than one roll to do a Coker rim. Bike shops can get the stuff in bulk in a big roll and just cut off the length that they need. So a bike shop would be able to wrap a Coker rim with a single piece of rim tape. Us normal people generally have to use the prepackaged tape that is just a little bit too short to fit all the way around a Coker wheel with one roll.

The strapping tape is the stuff you have pictured. Scotch Strapping Tape that has the threads running lengthwise all along the length of the tape. I used the 2" wide stuff in the second picture you had posted.

You can rip the tape lengthwise and the threads will act as a guide to get a smooth tear all along the length of the tape. I had problems getting long pieces to fit smoothly inside of the Airfoil rim so I had to use short pieces and lots of them.

Hi Seth,

Just bring along a spare Coker Tube in case it does blow up. That’s what Bronson did on the AUT when his 29’er tube started deflating, and what I used to change my tyre over when it wore out- I didn’t have the high pressure compressor or enough no-tubes sealant to configure back to tubeless on tour.

If you are after a light wheel (the whole point of the 29er exercise), then I’d stick with the Coker tyre- it’s lighter than the TA apparently.

To be honest, whilst it’s a noticeable difference, the trouble required with a 29’er configuration almost makes me wonder if it is worthwhile.


I didn’t have any trouble with the rim tape. Whatever’s in there isn’t moving around. The tube doesn’t slide on it easily, but it doesn’t seem to need to.

I’ve removed and replaced the tube three more times since trashing those first three and I haven’t had any more problems. The big change was to use dishwashing soap to lube the bead area of the tire, just like what John suggested with silicone spray. It makes the tire slide over the lever easily, which means the lever doesn’t have to move as far before the tire can be convinced to move into the rim, which means the lever won’t pinch the tube.

But after all that hard-won experience and scratching the rim, I think I’m going to stick with a 36" tube. I managed to ride on a patched 29" tube for an hour before it deflated and I didn’t feel much of a difference, so I’ll stick with reliability. (Slime didn’t help either, so I have to assume that a flat would often mean changing the tube.)

I got the whole process (including getting the wheel off and on past the brake) down to 40 minutes, but it’s a lot of work. I’ve had enough of fiddling with the gear. I’d rather be riding.