Is there a market for cobra tubes? let your voice be heard

[morph999]

If these cobra tubes come out in a 26 inch version, and they are $20 or less, I'm planning on buying one as a part of my survival kit when I'm 5 to 10 miles out and I get a flat. I don't want to be sitting on the side of the road for an hour fixing my bike. If you know me, I don't buy many things without seriously thinking it over or it being an absolutely necessity.

The guys from flybikesbmx.com want to know among electric bike enthusiasts like ourselves, which is more popular, 20 inch or 26 inch tubes? I'm saying 26 inch is probably more popular. What do you think?

The Cobra tubes are the ones where you don't have to take your wheel off to fix the flat....here is a picture

 

[John in CR]

Tell them to just make motorcycle tires in bike rim sizes instead of specialty bike stuff that always comes at a premium.

 

[gestalt]

Hear hear! sometimes I cry a little inside because there isn't a motorcycle tire I can throw a motorcycle tire on my 26" surly large marge rim. guess I'm gonna have to settle for hookworms. you know, I wonder what it would take to get some chinese company to make custom tires. Something like what recumpence has going on with those specialty rims.

 

[swbluto]

26 inch is more popular, no doubt, but I personally like 20 inch due to the gearing benefits.

 

[johnrobholmes]

Why not just use a motorcycle rim and go with tires already on the market? The economy of scales would not be in favor of "cheap" moto tires for a 26" rim.

26" would be most popular for the cobra tubes.

 

[morph999]

Do you guys think these tubes are a good idea? I'm only using it for a survival kit so I would just put it on my rim when needed and then when I got home, I'd probably switch it out for a regular tube and then put it back into my survival kit.

 

[nomad85]

If it works well then yeah it could be a lifesaver. beats lugging around the right tools to take off torque arms and the motor.

 

[John in CR]

Why not just use a motorcycle rim and go with tires already on the market? The economy of scales would not be in favor of "cheap" moto tires for a 26" rim.

26" would be most popular for the cobra tubes.

Would it be advisable to drill out hub motor spoke holes to fit the larger motorcycle spokes? If that's not a problem then sure.

 

[johnrobholmes]

most hubs are already sized for 12ga (2.3mm) spokes, so drilling over for 11 or 10ga isn't a big deal.

New tires require a new mold. A new rim size would only require a change to the roller separation on the machine, assuming the extrusion is already available.

 

[julesa]

I would buy some 26" cobra tubes right this minute if I could find some. And if the price wasn't completely out of the ballpark, of course.

 

[drewjet]

That's verry neat I would want a few in 20 and in 26. I think 26 would be most popular with this crowd.

 

[John in CR]

I would buy some 26" cobra tubes right this minute if I could find some. And if the price wasn't completely out of the ballpark, of course.

They look DIYable to me. A tube for a 700 might do the trick for a 26" tube. Just cut it and seal the ends with a taper at each end so they overlap in the wheel. I'd cut it halfway around from the stem, so the weights offset.

I like the conceptual approach using 2 tubes. One goes flat, just inflate the other. A specialty tube set designed specifically for that, including access to each through 1 valve hole in the rim is something someone should make.

When there's just no way around tube replacement, what about a repair kit for a tube cut all the way through? Then you just take a normal tube the size you need and cut it all the way through halfway around from the valve stem. That's so the weight of the repair to join it equals the weight of the stem for good balance of the wheel. I'm envisioning 2 rubber cylinders approx 3" long, 1 for the inside so you don't glue your tire closed, and 1 for the outside to work like a patch, but a patch that joins 2 ends together of a tube that's been cut all the way through. With a good joint, you could just leave it in the wheel afterward. I guess the only reason someone hasn't come up with this yet, is that taking the wheel off isn't really an issue with pedal bikes.

Don't forget to carry something in your tool kit to cut the old tube off, so you don't have to take your wheel off to get the tube off, defeating the whole purpose of the special tube.

John

 

[amberwolf]

I like the conceptual approach using 2 tubes. One goes flat, just inflate the other. A specialty tube set designed specifically for that, including access to each through 1 valve hole in the rim is something someone should make.

That's part of why I wanted to make a "dualie" rear wheel for CrazyBike2, so I'd have two tires/tubes on one wheel.

 

[John in CR]

I like the conceptual approach using 2 tubes. One goes flat, just inflate the other. A specialty tube set designed specifically for that, including access to each through 1 valve hole in the rim is something someone should make.

That's part of why I wanted to make a "dualie" rear wheel for CrazyBike2, so I'd have two tires/tubes on one wheel.

Amberwolf,

With the occasional spare moment I've been trying to figure out how to combine 2 hub motors to go in a single rim without much motor modification to end up with kind of a DIY Markcycle hub motor. Let me know if you come up with something.

John

 

[evblazer]

There was a discussion a few weeks on cobra tubes and one thing I mentioned is people on the BROL (bent rider online) are just cutting a tube and sealing with the patch glue and it is working well for them. I wonder if I could also use my vaccuum sealer to do it, don't let your wife/sister/mother see yah do it.

I like the conceptual approach using 2 tubes. One goes flat, just inflate the other. A specialty tube set designed specifically for that, including access to each through 1 valve hole in the rim is something someone should make.

... is that taking the wheel off isn't really an issue with pedal bikes.

I don't know if 2 tubes would help much. They have thorn resistant tubes that are probably as thick as 4 thin tubes and glass/thorns will still work your way through it. You still are going to have to peal the tire off and inspect the tubes to find all the offending material. A patch might be just as effective at that point.

Taking the wheel off is an issue with pedal bikes in my experience. Especially in muddy, cold low light conditions a hundred miles from your car or so. $#@*() tire. Lots of folks have chain cases for the rear or internally geared hubs that don't like to come off. On the front people have hub generators and sometimes those are a bit of a fight to take off depending on how they are wired. Probably a few other issue too and certainly not on the level of multiple torque arms with multiple hose clamps but an issue for sure. I'd really think people in racing might like these who had to self support since they pay alot more for advantages that might make a few seconds worth of difference.

 

[amberwolf]

I like the conceptual approach using 2 tubes. One goes flat, just inflate the other. A specialty tube set designed specifically for that, including access to each through 1 valve hole in the rim is something someone should make.

That's part of why I wanted to make a "dualie" rear wheel for CrazyBike2, so I'd have two tires/tubes on one wheel.

Amberwolf,

With the occasional spare moment I've been trying to figure out how to combine 2 hub motors to go in a single rim without much motor modification to end up with kind of a DIY Markcycle hub motor. Let me know if you come up with something.

John

(just to link this, since I ran across this old post in a search for something else)
I never have done that part, but I did finally try what I ended up calling a Twinnertube:
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=12500&p=562728
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=12500&p=569564
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=12500&p=570075


However, I did think of this: Two motors could be put "in series", chained together so they are in sync, one controller on each, halls lined up so they're electrically sync'd too, then secondary chain running to the twin wheelset itself. But a large enough motor (like what you have now) would make dual motors unnecessary.

 

[ebent]

I have a 20" cobra. Still in the box. I hope to never use it. I'm glad I have one. I would like to avoid the walk of shame.

 

[MadRhino]

That is the fastest way to fix a flat
I wouldn't use slime as prevention, because I like a light weight wheel
But a small bottle of slime and a CO2 tire inflator are fitting nice in the tool kit

 

[docnjoj]

We have used Cobra tubes 2X on the road with a CO2 inflator and it is the way to go. The cobra has been on my trike for about 3 months now and on Joyce's about a month with no leaks. Really easy to change the tube. Slime is too icky for me.
otherDoc

 

[MadRhino]

...Slime is too icky for me.
otherDoc

It is for me too. Slime makes a quick fix and ride in the trail so I can change tire and tube later, in the comfort of the garage.
There is always a few spare wheels ready to ride in the garage anyway, for I wear half a dozen every year.

 

[aroundqube]

If there was a 26" Cobra tube available I would add it to my pack.The next time I have to take the rear DD wheel off of the bike, I am going to try that idea of placing a spare tube around the frame stays and taping it up,out of the way.