Bicycle dual inner tube system

How to fit a dual tube system to a bicycle wheel that will enable you to deal with a puncture without having to remove the the wheel or need any tools other than a pump until you get home. When you get a puncture the second inner tube is sitting right there in the tyre waiting to be inflated.
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Step 1: Drill hole

Drill a hole in the rim of the wheel for the second valve stem at about 1/4 to 1/3 of the way around the rim from the original one. If your drill finds the going hard, start of with a small drill bit and gradually work up in size.

Step 2: Preparation

Completely empty the air from one inner tube (roll it up and squeeze). Pump just a little air in to the other inner tube, this will make fitting easier.

Step 3: Place one side of the tyre over the rim

Place one side of the tyre over the rim and then insert the flattened inner tube as straight as you can. Next insert the slightly inflated inner tube - push back the flattened inner tube to get the valve stem in place then, working from both sides of the valve stem fold the flattened inner tube under the slightly inflated one (as shown in the picture) as you work your way around the rim. It takes a bit of fiddling, I never claimed it was easy.
DoDo7292 years ago
Great idea, I have done this in the past and it works to get you home. If you do decide to do this, make sure the valve holes are directly across from each other to maintain wheel balance.
Unfortunately, almost all common rims currently available have the seam directly opposite the valve hole; drilling a hole precisely there would do most to compromise the rim. It's less of an issue with a steel rim, but the majority of common rims are aluminum i.e. the joint opposite the valve is pinned, rather than welded--as it is on a steel rim.

An alternative to double-stuffing your tire with a second tube (and having to do the jiggery-pokery necessary to have the valve of the outer of the two come through any extra hole in the rim) is a variation on 'toughy tape': cut away the beads and most of the side-walls from both sides of a scrapped--even bald--tire of a size to just fit inside the tire you already have on the rim, and lay that in before installing the tube and closing things up by installing the second bead of the whole tire.

The re-used tire's tread, in this case, is integral i.e. unbroken/uncut, at least along the center line. Choosing the proper size is important, though, as tires don't stretch much at all. If you're using 27" rims, choose a scrap tire from the 700 class. If you're using 700s, you'll almost certainly have to go with a much smaller width tire e.g. a 700x32C tire will need something like a 25C's carcass.

Another consideration for the bead-removal operation is the extent to which the edge that remains is 'feathered'; if you angle the cutting strokes in such a way that the edge is tapered, it's much less likely that that edge will cause any grief to the tube.

With this method, you are inserting an integral, second layer of fairly dense rubber between the tube (thin-walled, generally, and containing air under pressure) and the tread of the tire. Rubber cuts (or is most easily punctured) when it's wet, so having a layer of thick rubber, acquired costlessly, between the (possibly wet) tire and the under-pressure, thin-walled innertube means that anything that does get through the outside layer, will have also to pass through a fairly thick, almost-certainly-dry layer of rubber before reaching the vulnerable (but repairable) innertube. This arrangement should greatly reduce the likelihood of a flat, ceteris paribus.

Obviously, the downside to this approach is that that liner will have a mass, that mass will be at the circumference of the wheel, and you'll, therefore, have to accelerate (and decelerate) that mass in perpetuo. There's no free lunch--but you knew that.
Well there seems to be a bit of controversy on this subject. I guess the easiest solution would be to use a puncture resistant tire and a slime tube.
Puncture-resistant tubes ('thorn-proof' tubes) have something to recommend them--not least being that they're a purpose-fit manufactured item. However, the benefits have to be weighed against the costs: they're more expensive than conventional tubes; they're a bit more difficult to install and remove, especially on good-quality/tight-fitting clinchers; and, the additional mass still does have to be accelerated and decelerated. Net gain, if any, is small over the use of a liner as described in my earlier post.

As for slime, I don't recommend it, generally; I've found that its presence tends to make patching any eventual hole in the tube more difficult.
JustinsDIY2 years ago
i think This is a great idea! but what if a nail when completely thru both? i think a full proof system would be a dual inner tube system such as yours coupled with a seat belt lined on the inside inside of the tread. To me that sounds like an awesome peace of mind.
shooby3 years ago
whoa whoa the Plan B tire inflates itself around the valve of the initially inflated tire? Doesn't this raise the likelihood of a pinch flat, lead to uneven inflation, etc? This is a good idea, but there are kinks. Why not just patch it? The extra tube weighs about the same as a mini pump...
lynzay_4 years ago
Firstly, Excellent 'Ible' tyre redundancy :) genius!

Although If you want to make your bike tyres almost close to invincible, line the inside of the tyre with the Seatbelt from a car, the weave is so tight on a car seatbelt (to pass safety requirements) that a thorn wont get through it, especially not a nail.
unless you are breaking the sound barrier on your pushbike!

I grew up in rural Australia where the thorns and Bindys are huge, and using a good quality thick inner tube and the seatbelt,  I only changed about 3 pushbike tyres in my life. 
awesome idea when i find a scrapyard in my area and have the cash i will most definetley try this out on my old and new bikes. :)
That's good to know.
Ubuntu20094 years ago
Great idea, how ever i just line my main tyres with another tire that is smooth like a road tyre, ive road over glass, pins nails and no punctures. Not only that, once you have 2 tires per rim, if you ever did get a puncture say from a snake bite, then when your flat you can still ride comfortably, i rode my bike with both tires flat on purpose to test it, when flat there still = to roughly 20 psi. Just takes patients to get them on the rim lol.. I ride 100's of miles a week though so its worth it.
Not a bad idea..although i wouldn't drill a hole in my $200 rims...and my 3 ply downhill Maxxis tires work do my 3 ply Michelin X-Treme tires..haven't had a flat with them yet...and they ~sort of~ prevent pinch flats whare are the worst kind of flat... I also have extra thick tubes on my bikes...and knobby treads too :P if i had a cheap rim lying around i'd probbaly try it..but not on my $200 way in hell.. good idea though
Can you please tell me more about your 200 dollar rims! and please tell me why your tires are awesome!
yvesbigben4 years ago
Simply genial, well done. Thanks.
2high5 years ago
It would be a cool Idea to make a ready made doubletube. would be a killer at the expeditions. Great work mayte!
I have some far better alternative but you may need to find alternative to these as i just so happened to work for my dad industrial tyre fitting for years and theres a product we sold under the name of bulletproof (belfast) made by polycil which is a ployurethane liquid pumped in to tyres that makes them ride like pneumatic but completely invincible (the tyre casing can come off and you'll still get home). If you plan to attempt this one yourself with makeshift equipment please message or comment me it's dangerous like dead dangers. Another interesting option is closed cell foam filling, it's cheaper and lighter and is well proven for less brutal applications like wheel chair and shopmobility tyres, no idea how the pressures work with it. For a puncture sealant I suggest going to an industrial tyre place and ask about the black slime puncture sealant, its like the gooey stuff some bike use except it works and keeps the tyres really well balanced, I have seen this stop massive holes and seal a bolt onto the tyre because it was still in it
the green slime you can get at walmart work wonderfully! I like to ride my bike through forested terrain and no trail riding which would have been impossible without the slime. You can tell that it works when you notice a lower pressure in the tire when you get home but its not flat. just add some more air and its good to go for next jaunt. I ran over some barb wire and it punctured my tire but the slime performed superbly. There is also a orange colored slime but I don't think it works as well.
There's a similar white stuff meant for cars that comes in spray cans. It saved me today. I got two flats in five minutes, can you believe it? Nasty thorns! The only thing that I can complain about was all that white foam spraying me and my bike.
Eh the green slime is ok, this balck stuff I speak of is unholy though, it's like witchcraft... also I still have a bulletproof bike tire sitting here... The green one is decent but the orange one is a simple waste or money...
Esmagamus5 years ago
I thought about this once, but doesn't it make rolling harder? You can always buy a can of puncture repairing foam that is meant to be used in cars and fill your tubes with it like I did 5 years ago. Today, I had a puncture (yes, I still have the same tubes) and I watched how the foam came out of the hole as liquid expanded where the pressure is lower and quickly covers the hole. Right then, I saw another thorn sticking in the tire and thought "damn thorn, I almost had two punctures at once!" I pulled the thorn and presto! Another puncture! Anyway, two punctures in the same day and I still rode another 40 km back home.
mikesty7 years ago
Great idea until you hit a nail, or some uber spikes, and end up deflating both tires :) This is a good idea - I will show this to my teenage bike friends of mine. I'm not a big fan of bikes myself (I didn't learn to ride until I was eight), and I still pretty much suck. Living out in the country, biking isn't an optimal form of transportation - either you mountain bike like a crazy man, or you just chill :) I have an old Panasonic Villager that needs new tires and probably tubes. I'll be sure to consider this.
Most flats I get living in a city are from small items. It's usually some tiny piece of glass. This idea would totally work well as an emergency backup.
Ah. Living in the wilderness that is Pennsylvania, the things we hit are giant nails ;) Maybe it's just me, but it seems like the majority of Instructablers are urbanites.
sennomo mikesty5 years ago
Yes, they are mostly urbanites. There are lots of trendy track bikes here and no mention of dodging road apples or farm equipment.
mikesty sennomo5 years ago
Every week or so I get a notification that someone has replied to a two-year-old post. Usually it's junk, but this was hilarious. Thanks for making all those check-ups worthwhile.
Antexter6 years ago
How about blowing up both of the tubes next to each other? This way you get a very comfortable ride and if you blow one up the other is already half inflated, another advantage is you wouldn't blow it up by going up a curb as it could take much more pressure.
toyotaboy6 years ago
What you really need is a special inner tube that has a hole in it exactly 180° away from the stem (that's sealed off), that way the inflated tube can slip right through the deflated one.. and then pop off the outside tube when it gets pierced, toss it, and inflate the other one.
cycling2477 years ago
The only thing better then two tubes is NO TUBES!

I don't work for them, but their stuff is quite good. I would HIGHLY suggest checking out their video segments!
moon1617 years ago
I used to make a Z fold around the puncture when I was stuck with a pump but no tube or patch kit. I put a few hundred miles on such a fix once.
Wade Tarzia7 years ago
Great idea, and very well discussed! How long have you been doing this? Have you "tested to destruction" so to speak under natural conditions. This would have saved me changing tubes in the rain during my irish cycling/camping expeditions (Ireland is hard on tires). -- WT
kph53867 years ago
cool idea. you could inflate both tubes side by side instead of stacking them -one on the left / one on the right. Inflate them both carefully with equal amounts of air, count the strokes on your floor pump. that way when a puncture happens the other tube is already half full, most likely still ride able. or, you can even leave the ‘backup’ tube’s stem inside the rim. just inflate it half way before finishing the tire install. no drilling into the rim.
NinjaTek7 years ago
This would have saved my ass from having to call my girlfriend to pick me up a couple weeks ago. Absolutley brilliant, this seems incredibly marketable to me, maybe it's just me.
trebuchet037 years ago
very cool idea :D I don't think it would fit in my road bike... but I usually carry some patch goo and a Dr. Phil -- and its gotten me home in the past :P But, my father has a bike he uses to transport himself and equipment in one of the ship yards he works in... there's always crap on the ground causing trouble...
dhammy01107 years ago
Great idea! Unfortunately, the spare tube will be kinked around the valve of the original tube, but at least it should get you home. Now how to figure out a detachable valve system for the original!
brob dhammy01107 years ago
of course you could use one of those sausage style innertubes as the spare (they aren't a complete circle) but then they're so easy to put on after a puncture (no need to remove the wheel) then this project is almost redundant. Good idea though. I used to know some BMXers that would put 3 or 4 tubes in their tires fo the extra pressure. Dunno if it worked.
that is an awsome idea

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