Pumps vs. CO2 inflators...

[galen_52657]

It was a ride from hell as far as flats were concerned....

Got all rev'ed up and suited up hoping for at least 2 hours on Sunday as the sun came out, temps were in the high 30's - low 40's and weather was supposed to turn....

Unload the tandem and the front tire is flat...

Change out the tube just as 2 guys on singles return from thier ride to where my car is parked. We chat as I am working the tire back on.. One of the fellows sees I have a pump and offers to inflat the tire with his CO2 inflator... and I accept (I have always carried a pump on all my bikes).

So, we are off and about 15 minutes into the ride when I feel the roughening ride of the air comming out of my back tire....

So, off with the back tire, out comes my last tube, get it changed out and begin inflating with the Crank Bros. pump.

http://www.nashbar.com/profile.cfm?category=106&subcategory=1076&brand=&sku=8507&storetype=&estoreid=&pagename=

What a POS. And to think the bike shop guy recomended this pump! It does not have a place to hold the pump at the head and with 48 spoke wheels, I could not get my fingers between the spokes and around the pump head to work my pumping arm against my stationary arm. After futzing around for about 15 minutes (while my stoker wondered off for a bathroom brake and took shelter behind some big rolls of hay) I managed to get 75 psi in the tire. And this pump is supposed to inflate to over 100... maybe if I had a month..

So we had to cut the ride short. I got as much workout fixing the flat as I did riding...

I am worried that if I carry an inflator instead of a pump, I may use up all the inflators on some God-forsaken ride and get stuck....

So I think I may buy a good-old full sized frame pump.

Comments/recomendations?????

[slvoid]

Innovations sells a co2 pump that also converts into a hand pump if you run out of cartridges. That's your best bet. Use the hand pump to test out the tire, then after a minute of riding at low psi, when you're sure it won't leak, use half a cartridge to air it up all the way, that way you still have half a cartridge that will last an hour or so in case you get another flat. Plus you can always carry 2-3 cartridges with you.

[2manybikes]

Innovations sells a co2 pump that also converts into a hand pump if you run out of cartridges. That's your best bet. Use the hand pump to test out the tire, then after a minute of riding at low psi, when you're sure it won't leak, use half a cartridge to air it up all the way, that way you still have half a cartridge that will last an hour or so in case you get another flat. Plus you can always carry 2-3 cartridges with you.

Are you refering to the newer pump that looks more like a regular mini pump? Have you used it a few times? Anything else good or bad about it that comes to mind?

I have struggled with the small one that looks like an inflator, it's almost useless.

[skydive69]

Innovations sells a co2 pump that also converts into a hand pump if you run out of cartridges. That's your best bet. Use the hand pump to test out the tire, then after a minute of riding at low psi, when you're sure it won't leak, use half a cartridge to air it up all the way, that way you still have half a cartridge that will last an hour or so in case you get another flat. Plus you can always carry 2-3 cartridges with you.

I use this pump, and it is great! I had a bad day recently and ran myself out of my two C02 cartridges, and was able to pump up my tire enough with the pump portion to get home.

[TandemGeek]

So I think I may buy a good-old full sized frame pump. Comments/recomendations?????

Frankly, I find full-size pumps to be a little less complicated and far more predictable with regard to their intended purpose. Moreover, for non-competitive events involving road bikes and tandems in particular, I also see no point in chasing any weight savings on the minimally required field repair equipment that might drive me away from a full-length frame pump vs. a compact model or C02 cartridges.

With regard to C02 cartridges, I would say that I have been let-down or left holding by C02 cartridges far more often than a good old fashion frame pump. Of course, if I'd only been let down by C02 once that would out number the times that my frame pumps haven't worked... and worked quite well. The Blackburn model "seems" to be easier at getting the 120+ psi levels that we run on our tandems and the brushed aluminum air cylinder has always looked nice hanging on the bike vs. the black or painted-to-match Zephals.

Pumps, in general, will provide you with an infinate volume of air which, at least to me, is really important when it comes to fixing flats. Even in those flat tire situations where I've had C02 cartridges around I've only used them to bridge the gap between using the pump to pre-inflate the tube enough to permit fitting it into the tire for remounting -- which is the only way I know to prevent inadvertently pinching the tube and arguably making it easier to fit the tire to the rim -- and then perhaps saving a minute or so by "blasting" the tire up to running pressure IF the cartridges doesn't peter-out or pop-off the stem before it gets there.

As for my preferences, I've used the Zephal HP-1's since ???? (they were invented?) and Blackburn FP-1's since '97. I have both in the stable, but prefer the Blackburn... well, at least the pre-'05 models which were far more affordable and better looking than the new carbon stick. On the bright side, your Etailer of choice has them on close out for $24.99. Just be sure to get the right size for your frame.

http://www.nashbar.com/profile.cfm?category=106&subcategory=1074&brand=&sku=11157&storetype=&estoreid=&pagename=

I have a slew of other pumps in the shop.... Topeak RoadMorph, Blackburn mini-pumps, etc... and they'll most likely remain there for a long time. I carry a mid-size, large barrel Blackburn pump in my Camelbak when we ride off-road and the RoadMorph gets packed in the S&S cases for trips as a "back-up floor pump" in the event someone fails to show up with one, even though I'm not sure it's any better than the FP-1 (probably just trying to justify the expense).

[Rincewind8]

I recently bought this pump:

http://www.performancebike.com/shop/profile.cfm?SKU=17774&subcategory_ID=4361#

but I got a version with aluminum barrel. I used it just once since, but it was very useful. It has a retractable valve head and kind of can be used like a floor pump. It also didn't take me very long to pump up a tire.

[bidaci]

I used to carry just the CO2 cartridges until I got a pinch flat and couldn't get my tube seated properly with the CO2 cartridge alone. I now carry a small pump to get just enough air in the tire to seat the tube and tire, or locate a pinch for a quick patch. I then use the CO2 cartridge to fill the tire up completely.

[SDS]

Blackburn water-bottle mount medium-sized frame pump for road tires.....

Check equipment at base camp before depending on it in the field....

Use flat-resistant tires (kevlar belt), Velox rim tape, learn how to install a tube so it doesn't get pinched, inspect assembled wheel/tube/tire for entrapped tube.

Inspect tire that has gone flat for embedded sharp debris and small cuts/holes.

If there is anything worse than one person not getting to ride, it is two people not getting to ride. Maintenance and inspection of a tandem is about four times as important as on a single, because the owner is representing to prospective vic- I mean, PARTNERS, that the bike is ready to go all day.

[stapfam]

I used to carry just the CO2 cartridges until I got a pinch flat and couldn't get my tube seated properly with the CO2 cartridge alone. I now carry a small pump to get just enough air in the tire to seat the tube and tire, or locate a pinch for a quick patch. I then use the CO2 cartridge to fill the tire up completely.


The choice of pump is vital. It has to be usable, fit the bike so it will always be on the bike, be of the high volume type of pump, and be of a quality that means it will always work. These do not come cheap, and I have always found the Blackburn Mammoth Pump excellent. That was untill I got the Tandem where a higher pressure into a larger tyre is required. I now carry the Blackburn and use this to inflate to as high as I can get, but carry a CO2 cartridge to get that final bit of inflation for when either the Pump or I have had enough.

Edit-- Whilst writing this SDS replied so that is two votes for a blackburn pump

[galen_52657]

All good posts and recomendations.

I did try the Crank Bros. while the bike was at home and got the tire up to about 80 PSI but it was warm in the house... not trying to handle ice-cold rims with stiffening digits.....

I think I will follow the knowledgable advice of our esteemed members; Livngood, SDS and Stapfam and spring for the blackburn.....and some tubes...!

[TandemGeek]

.....and some tubes...!

In that we run 700x23 & 700x25 tires on our road bikes and tandems, this is one of my favorite specials:

http://www.performancebike.com/shop/profile_combo.cfm?SKU=14301&estore_ID=&subcategory_ID=5411&CFID=43670367&CFTOKEN=87971265

I buy these about once every 18 months or so... $2/ea and they work just fine. I usually try to combine my tube buy with sales on tires, chains, and derailleur cables -- you know, the consumables of cycling. Just keep the tires and tubes out of the sun in the garage or basement and they'll stay "fresh" for quite a while.

[allgoo19]

There was a time I walked ten miles because of flat tire. I keep a CO2 just for emergency but I don't totally depend on it. If you goof, and many things can go wrong, you are out. If I go long and don't know whether gas stations are near by, I'll bring my frame pump. Like some people said, push against the floor type(like Sigma) works good. Mine is Performance brand called, MiniMax. It goes 100+ PSI.

[fogrider]

On my tandem, I run two innertubes in one tire...I drilled an additional valve stem hole 180 degrees from the existing and inflate 50% pressure in each. I run 25 cm wide tires in front and 28 cm in the rear. When I do get a flat, I still have 50% pressure, nice at high speed. And at that point, you can just pump up the innertube that is not flat and off you go.

As for a pump, I too would recommend a full size frame pump...on a tandem, there should be lots of room to mount it. I too agree that the blackburn is the way to go.

[lisitsa]

I had all these problems with pumps, so I got an Air compressor designed for a car for 30 bucks from KMart (equivilant of walmart). It works wonders. Before every ride, I just connect it, and switch it on, and in seconds it reaches my desired pressure. Even better, it's got a battery so you don't need to connect it to anything to pump up the tire, and it has Jumpstart for the car as well.
For home use, electric pump is the bomb. For use on the road, I agree with everyone that the minipumps are damn inconvenient.

[bassplayinbiker]

On my tandem, I run two innertubes in one tire...I drilled an additional valve stem hole 180 degrees from the existing and inflate 50% pressure in each. I run 25 cm wide tires in front and 28 cm in the rear. When I do get a flat, I still have 50% pressure, nice at high speed. And at that point, you can just pump up the innertube that is not flat and off you go.

As for a pump, I too would recommend a full size frame pump...on a tandem, there should be lots of room to mount it. I too agree that the blackburn is the way to go.


how does this work? Ive never heard of this before. i just dont see how 2 50% tires would = 100 % inflation. two soft things dont = a hard thing. (right?) (no pun intended)

no offense, I would like to hear more details, i Like this idea.

[galen_52657]

how does this work? Ive never heard of this before. i just dont see how 2 50% tires would = 100 % inflation. two soft things dont = a hard thing. (right?) (no pun intended)

no offense, I would like to hear more details, i Like this idea.


I have never heard of running two tubes... I am not going to try this but....

I am guessing he inflates both tubes a little at a time to keep the pressure ballanced in each tube.

My concern would be this: If you are running a 700 x 28 tire do you use two tubes for smaller tires? (say, 700 x 19-23). Or, do you stuff two proper sized tubes in the tire?

I would worry that there might be some bead seating issues with the tire at high pressure, or that if you use a smaller tube than designed for the tire you are running, if one tube goes flat the other tube will be stretched or that if you get a pinch flat, it could very well flatten both tubes.

Still, a novel idea. If you did run two tubes of the proper size, if you did flat one you could just remove the flattened tube, top off the tube that remained and carry on...saving a little time.

[Murrays]

For home use, electric pump is the bomb.

I've seen people at rides with electric pumps, but I would opt for a good Silca floor pump. For topping off before a ride, I put on the chuck, pump 3 or 4 times and I'm done. I wouldn't mind having a compressor, air tank and regulator for topping off, but that's too much expense for the convenience gained.


50% pressure in each.

The other poster was right, inflating two tubes to 50% pressure will result in...50% pressure in the tire. As for just pumping up the tube that isn't flat, you're likely to end up with another flat if you don't determine what caused the flat in the first place.

-murray

[jazzy_cyclist]

I was very unhappy with the pump that came with my bike - getting it to 80 psi would require that you be "Ahnold". Got a Topeak Road Morph for xmas that I have yet to try out.

I'm sure this stuff is all that much worse on a tandem...

[Steve Katzman]

I vote for the Topeak Road Morphe. I've been using them on most of my bikes for at least 5 years with great success. I have never owned a Blackburn frame pump, but I have a Zephal on one bike - it's OK but the Road Morphe is much easier to use. I like the ability to put it down on the ground and pump it like a floor pump. Plus the Road Morphe has a built in gauge to let me know how much pressure is in the tire. The only bad part about owning one is that your friends with mini pumps will want to use it if they get a flat when riding with you. I think, all told, my friends have used it more than I have.

As a matter of fact, on last year's Georgia Tandem Rally, the organizers (Roger and Eve) got a flat on their triple on the last day's ride. They inflated it with a full size frame pump (not sure which one). They pumped and pumped but it would not hold air. The tube stem had wiggled itself loose from the pumping action so the tube was kaput. I came along with my Road Morphe and made easy work of reinflating the second tube. The team with the flat and the bystanders were impressed. Yes, I know there is a proper technique for using a frame pump and from what I could tell the pumper was quite experienced and was doing it correctly. I feel there is no substitute for a rubber hose decoupling the pump action from the tube stem. That, and the up-down pumping action of a floor pump seems so much more natural than the sideways action of a frame pump. Maybe that's why floor pumps are all designed the way they are.

[flyingscotsman]

I used to carry just the CO2 cartridges until I got a pinch flat and couldn't get my tube seated properly with the CO2 cartridge alone. I now carry a small pump to get just enough air in the tire to seat the tube and tire, or locate a pinch for a quick patch. I then use the CO2 cartridge to fill the tire up completely.

My Co2 inflator converts into a hand pump.

Love it.

[TandemGeek]

I feel there is no substitute for a rubber hose decoupling the pump action from the tube stem. That, and the up-down pumping action of a floor pump seems so much more natural than the sideways action of a frame pump. Maybe that's why floor pumps are all designed the way they are.

There's some truth to that. Me, I always look like I'm doing something obscene whilst pumping up a tire during a road-side repair (more often someone else's vs. my own). Owing to the frame pump's hard connection to the valve stem, I rest the wheel/tire against my upper thigh with the valve stem at the 12:00 position so that the pump head presses against my leg. As you can now visualize, this means the pump is perpendicular to the wheel with my left hand holding the lower grip of the pump and my right on the articulated T-handle moving out and back from the wheel.... indeed! Anyway, although provocative, it does prevent the valve stem from getting damaged and it also provides for a more efficient pumping action than any other technique I've tried with a rigid frame pump.

My only complaints about the Road Morph are the smaller air volume-per-stroke and the ungainlyness of it hanging on the frame, what with all its exposed accoutrements; nits to be sure. Pressure gauges are nice but I think you can reach a point as a cyclist when you can get your tire pressure "close enough" by learning how the tire "feels" as you press your thumb into the sidewall.

[SDS]

With the Zefal HPXs, I refuse to let the wheel touch anything except the ground for fear of fracturing the valve stem. I just bring one hand to the other, with the valve stem at the top of the wheel, with the bottom of the wheel resting on the ground, keeping the valve stem and the rim motionless. I have accidentally achieved 160 psi that way, and I would guess 220 would not be too hard as long as nothing let go. At 190 lbs, most people let me inflate their tires.

It seems to me that a lot of MTB racers use two tubes in one tire/rim. If one goes flat, they keep right on going.

[TandemGeek]

On my tandem, I run two innertubes in one tire...I drilled an additional valve stem hole 180 degrees from the existing and inflate 50% pressure in each. I run 25 cm wide tires in front and 28 cm in the rear. When I do get a flat, I still have 50% pressure, nice at high speed. And at that point, you can just pump up the innertube that is not flat and off you go.

I've seen where a few off-road MTB racers had adopted the practice of stuffing a second, un-inflated inner tube in their tires that could be inflated via a valve sticking out of a second valve hole drilled into the rim. Thus, in the event the first tire was pinched the tire could rapidly be re-inflated with a C02 catridge without removing the tire or the 1st, now punctured tube. However, there's a world of difference in the amount of room and psi levels associated with a 26" fat tire bike vs. a 700c narrow tire tandem, never mind how the two-tube installation is used. Moreover, this was for race situations where time was of the essence.

So, that said, and as others have asked, how does this work? Even assuming that each tube ends up with 50% of the total volume of air required to achieve the tire's recommended psi, I would expect that there would be at least three "issues" with this arrangement:

1. Let's just assume the loss of air in one tube or, put another way, a 50% loss in the total volume of air forced into the tubes to achieve a given net amount of air pressure inside of a the bicycle tire. If the tire is normally inflated to 100 psi, a loss of 50% of the total air volume in the tire would result in something far less than 50 psi would suggest; it isn't much. Thus, your 2nd tube would likely make your tire no more useful or safe to ride on than one that was flat, i.e., you'd still be pretty much riding on the rims. NOTE ADDED @ 7:40pm: Just inflated a 700x25c tire at home to 50 psi and it's a little more robust than I suspected, but still basically a rim rider under tandem team weight.

2. The addition of the second tube would invite a little bit of chaos inside the tire in that, an inner tube is designed to fit inside the tire with a uniform, symetrical thickness. This close fit between the tire and tube ultimately plays into the tire's contact patch, rolling resistance, and heat build-up from friction. The second tube would -- even under optimum conditions -- create a new source of friction between the tubes within the tire, create variability in the contact patch along the seam where the two tubes meet, and increase rolling resistance, never mind the added rolling weight of the 2nd tube.

3. With regard to flat protection, while a good number of flat tires are caused by sharp objects penetrating the tread, many others are pinch flats caused when a bicycle tire hits a blunt object, pothole, or expansion joint. On tandems, the dreaded "snake bite" is the most common type of pinch flat, where pinch cuts occur on both sides of the tube. Unless you could ensure that your tubes remained "stacked" on top of each other, you could easily end up with both tubes being pinched by a single impact.

NOTE ADDED @ 10:00pm: OK, I couldn't resist the temptation and drilled an extra valve stem hole in an old T217 rim and did the two-tube installation. It's an intriguing concept that I would have to road test for a few hundred miles before passing judgement on. My original concerns remain, i.e., better than a flat, but not by much; implications on rolling qualities and treadwear; and in practice would it work.

Additional observations from the experiment are at post #27 in this thead: http://www.bikeforums.net/showpost.php?p=857310&postcount=27

[Murrays]

if the tire is normally inflated to 100 psi, a loss of 50% of the total air volume in the tire would result in something far less than 50 psi.

While your post makes several good points, this one is technically inaccurate. The relationship of pressure to volume is described in the formula PV=nRT or pressure X volume = amount of air X constant (R) X temperature. Since the amount of air in one tube and temperature don’t change, it reduces to pressure times volume = constant.

In other words, if we double the volume, the pressure is cut exactly in half.

-murray

[TandemGeek]

While your post makes several good points, this one is technically inaccurate.

Guilty as charged; Boyle's Law is alive and well (at least I think it's Boyle's Law).

Original is now re-edited to reflect the original intent of the thought.

Good gravy; what a horribly written post that was. Never compose when you're in a hurry.... Some additional edits have been made.

[zonatandem]

Flat tires are a fact of life we have to live/cope with when riding!
We use the Topeak Mt.Morph . . . 100 pump strokes give 100 lbs of air in our 25mm tires.
Topeak's mounting system seems a little Rube Goldberg-like: run a velcro strap through a plastic thingie (receiver) and secure it on a convenient tube on the tandem; then clip the pump into the receiver, etc. . .
We simplified that by putting epoxy on the plastic thingie (receiver) and installing it on the boob tube, thereby by-passing the velcro system. Clip the pump into the receiver and voila! . . . you're ready to roll!
Have used all kinds of pumps since the early 1970s, and the Mt. Morph is the cat's 'meow' for us. It is lighter and shorter than the road model and pumps up air just as quickly. Having it convert to a mini-floorpump is really a marvel in form and function. No more breakiing of presta valve stems by over-enthusiastic pumping action!
We do carry an Innovation's CO2 inflator as a backup . . .
We normaly carry one spare tube in our repair kit + patch kit. On tour we carry 2 spare tubes.
Better to have it and not need it, than to need it and not have it!

Pedal on TWOgether!
Rudy and Kay/Zonatandem

[TandemGeek]

OK, I couldn't resist the temptation and drilled an extra valve stem hole in an old T217 rim and did the two-tube installation. It's an intriguing concept that I would have to road test for a few hundred miles before passing judgement on. My original concerns remain, i.e., better than a flat, but not by much; implications on rolling qualities and treadwear; and in practice would it work.

Installation observations: I used two standard 700x19-26 butyl tubes from Performance and a 700x25 Vredestein Fortezza tire mounted on a Mavic T217 rim. You must use new tubes or, for previously used tubes, roll-up or "suck" the air out to get them completely flat before installing them in the tire. The tubes do, in fact, stack in on top of each other quite nicely. The only "blip" is where the inner-most tube must duck around the outer-most tube's valve stem. Inflation is somewhat entertaining and reminiscent of "Dr. Science" shows. I used two floor pumps with gauges and as you would expect, the tubes will both register the same psi regardless of how much air goes in each one. Thus, you have to count strokes to make sure they each end up with the same volume of air as you work your way up to your targeted net psi. Given a cursory look, there is no hint that there is anything special about the tire/wheel until you notice the 2nd valve. On closer inspection of the tire, it also wasn't obvious that there was much going on inside the tire, although I could detect where the two tubes crossed near the 2nd valve stem. Interestinly enough, the tubes may or may not let you deflate one independently of the other as the open valve stem gets "pinched-close" at the base of the stem once the 2nd tube starts to compress it. Thus, the 50 psi test is best conducted by deflating both tires and then inflating one to 50 psi. With 50psi in the tire, my weight of 170 lbs was enough to fully deflect the tire down to the rim such that it looked like an uninflated sew-up tire where the rim/tire contact the ground. So, while there technically is 50 psi in the tire, most of it is displaced from under the contact patch. As for other observations, you can feel the extra 120gr of weight just holding the wheel. I suspect the rolling characteristics would also yield some sense of the added rolling weight.

In sum: If there was a good way to "plug" the extra valve hole in some good rims I might be tempted to play around with the set-up to see how it performed in the wild. If it didn't adversely impact tire wear, it would certainly merit use for commuters, particularly those who ride in super-cold or adverse weather conditions where the speed with which a puncture could be addressed would be reduced to the time it takes to pump up the 2nd tire vs. muking around with the removal & reinstallation of the wheel, tire, and tube. It also has merit for our off-road tandem's front wheel which uses a bolt-on 20mm axle; something that makes a flat tire in the backwoods a royal PIA. In fact, that IS something I may consider having fiddled around with the dual-tube installation. Given the large volume of the 26 x 2.4" tires we use and the lower psi's used on off-road bikes and tandems (35 - 40 psi), the dual tubes could prove quite helpful for any front tire puncture. Of course, it's rarely the front tire that flats on an off-road tandem....

Again, it would be good to hear more about how the installation works relative to tread wear and just how much added security / bike control they provide in the event of a front or rear tire puncture.

[zonatandem]

Sounds like the double tube theory is a bit more bother than it is worth except, possibly, in a real off-road racing situation where seconds could make a diffference in placement.
Much TWO-do about nothing?

[TandemGeek]

Sounds like the double tube theory is a bit more bother than it is worth except, possibly, in a real off-road racing situation where seconds could make a diffference in placement.
Much TWO-do about nothing?

It would sure make fast work of a flat IF the second tube didn't create problems inside the tire; that's my real concern. Again, if I was a commuter or did a lot of riding in adverse conditions, the 2nd tube would be worthy of further investigation: how cool would it be to puncture during a wet, 37 degree ride home and know that all you had to do was verify which tube was still holdling air and give it a blast from your CO2 cartridge or a few strokes with the frame pump (with your fingers cross in the hopes that you didn't have something penetrating the tire that would puncture your 2nd tube as it came up to pressure). However, I'd probably opt to use 700x32 or even 700x35 tires running lower psi to minimize the potential inside the tire / tube-related issues in those circumstances.

[zonatandem]

IF . . . ???
Commuted for years . . . always gave myself 'bout 10 x-tra minutes time in case of puncture/problem. Only happened a couple times; still got to work on time.
However, if so inclined, it would be worth a try; but, being retired now, don't have too many time constraints when riding the single or the tandem.
Pedal on!

[Brian]

On our tandem we use one of the Sigma pumps that converts to a mini floor pump, with a hose and gauge. We flatted on our first ever ride, and yes, the 20mm thru-axle was a pain. I see a Marzocchi DJ in our future for the QR20. We now run a slime tube up front, because a bit of extra rotating weight is not a worry. I haven't used the road style "stick" pumps in years, just compact ones. I found the Sigma did a great job and has an easy to use quick mount as well. The two tube idea intrigues and frightens me as the same time.

[SDS]

With 20mm thru-axle wheel/forks, and small hole(s), is it not possible to lift a bead out with the wheel still on the bike, pull the tube out, find the hole(s), fix them with peel off / stick on patches, and reverse the process to restore the wheel to use? This won't work with big holes, but it should work with small holes.

With the previous generation of patch kits, where instant repairs were less successful, a lot of us became accustomed to changing the tube out during field repairs. The peeler patches are an advance in ease of use and reliability. With a 20mm thru-axle, perhaps they could be used with an improvement in convenience in comparison to removing the wheel to change the tube. It would still be my choice to change the tube with QR wheels on a group ride because that has the highest probability of one-stop fix. By myself with no schedule requirements, I often repair the tube with a peeler patch to preserve my supply of spare tubes. One never knows what will happen around the next corner.

Of course, on a tandem with rim brakes only in steep terrain, the usual rule applies: vigorous use of the brakes that warms the rims can melt the patches off the tubes, and then they can deflate.

[Brian]

It was a charity event, and I didn't want to sit by the roadside watching little kids pedal by while I looked for a hole in the tube. I also like to run a gloved hand through the inside of the tire before I put everything back together. Force of habit. I think the sag wagon handed out tubes also, but we packed a few spares. We hadn't gotten the bike fully sorted, and my wife didn't feel well, so the break was welcome anyway. A guy on a unicycle finished before us. 6 months later, still no flats.

[Daily Commute]

The Topeak pumps are great--I use the Mountain Morph. Whatever pump you get, make it has a flexible nozzle. Ones without the nozzle can damage the stem. On long rides, I also carry a couple CO2 cartridges as back up in case I somehow damage the pump.

[galen_52657]

Mark,

Regarding your 2 tubes-per-tire test, can the tubes be side-by-side instead of one on top of the other? Then, there would be no overlap at the valve.

[TandemGeek]

Mark,

Regarding your 2 tubes-per-tire test, can the tubes be side-by-side instead of one on top of the other? Then, there would be no overlap at the valve.

I suppose if someone really wanted to work at it, yes. However, side-by-side vs stacking would almost guarantee that you'd end up with the irregular seam where the two tubes butt up against each other falling on top of the tire's contact patch. Of course, this assumes that if you stack them against the back of the tube they will, in fact, stay stacked as you inflate the tubes and during use. I'm not quite sure how those things would play out, theoretically or otherwise. Also, assuming that you were successful in getting the tubes to rest side-by-side, you've almost guaranteed that both of your tubes would be punctured in the aforementioned "snake-bite" pinch flat scenario. Moreover, the positive aspect of the stacked tubes would be that in the event of a puncture from something small that pentrated the tread, the flatted tube would provide a few mils of added protection for the second tube... well, maybe. According to Murphy's Law, small shards of glass and other pointy things that make their way into tires would likely penetrate three layers of rubber as the 2nd tube was inflated to full operating psi -- and of course there would be witnesses (also part of Murphy's Law).

Finally, as a data point for other would-be experimenters, I should note that you can't put the 2nd valve hole 180 degrees away from the existing valve hole as that would be the location of the rim's weld joint. Instead, it must be off-set one or two holes to the right or left. I suspect that the weight of the material removed from the rim to create the hole would not fully off-set the additional weight of the 2nd tube's valve which would give you some additional wheel balance issues... noting that most wheels already have balance issues.

[jazzy_cyclist]

This two-tube thing is pretty wild, although I'm sure that with my luck the nail would get both...

I haven't tried this, but I have heard that in the case of an unrepairable tube, you can cut out the "bad spot" and "tie off" both ends and that it will still function (a mountain biker told me this, so hard to say what degree of performance he meant by "function"). If this is true, then you could still stack the two if the "outer" tube had it's "tube-ectomy" where the valve stem of the "inner" tube was located.

I must admit that I'm getting the feeling that we passed the "it's not worth it" point a while ago, but it is definitely intriguing...

[2manybikes]

This two-tube thing is pretty wild, although I'm sure that with my luck the nail would get both...

I haven't tried this, but I have heard that in the case of an unrepairable tube, you can cut out the "bad spot" and "tie off" both ends and that it will still function (a mountain biker told me this, so hard to say what degree of performance he meant by "function"). If this is true, then you could still stack the two if the "outer" tube had it's "tube-ectomy" where the valve stem of the "inner" tube was located.

I must admit that I'm getting the feeling that we passed the "it's not worth it" point a while ago, but it is definitely intriguing...

I have read about the tube cut and tie method many times. Maybe it will work on a mtb tire, I don't know.
I spent a lot of time trying to get it to work on a 700cx23mm road tire. The knot is so big that you can not get the tire bead on the wheel well enought at the point where the knot is. It was worth it that day as my glue dried up and I used up my spare tube. The cell phone was very worthwhile that day.

[spacerconrad]

I've tried minipumps, frame pumps, CO2, and finally settled on what I carry on all rides, no matter what I'm riding or where. The Topeak Morph series ROCKs! I used my first one at home and on the road, and after 2 years of pumping every tire that presented itself (I've traditionally been one of the cycling mech support crew on the Arkie 100 rides here) and finally wore it out. I can probably fix it, but I bought two more, one for my sweetie and another for myself, as well as a Joe Blow to use at home or at the car.
It doesn't look as slick as some, not as light as others, but fellow riders' faces light up when help rides up with a floor pump.
The other models similar to this may also be great, though I've been so taken with the Morph that I haven't bothered trying them.

[spacerconrad]

I don't think I'd bother with something like this on a single bike, but Jacquie and I suffered a flat on the rear tire of our tandem (700x35 Pasela TG) and couldn't get stopped in time to save the sidewall. The chip and seal surface chewed it up pretty handily. Some sort of redundancy is certainly an attractive idea in that sort of situation.
Now we carry a spare tire (and spokes, learned that one the hard way, too.)

[TandemGeek]

Now we carry a spare tire (and spokes, learned that one the hard way, too.)

As someone who has loaned out a few spare tires, both out of the tool box in the car and from the seatpack under my saddle, let me fully endorse the suggestion to carry a spare tire for your tandem. We didn't bother with it until we were on tour in California and one of our fellow teams shredded the rear tire on their tandem. Now, as luck would have it, one of the teams had a spare... just one problem: The spare was a 700c and the tire that was shredded was a 27". There's a very long story that goes with this particular day on the bikes that included some problems with really old spare tubes. So, while it wasn't "our turn" we certainly learned a valuable lesson about having a spare tires & tubes that are in good condition on the bike. I now make a point of rotating my foldable spare tire out of the seat pack and onto the front wheel of the bike when the front tire moves to the back to replace the worn-out rear tire. This ensures that the spare doesn't become too old or otherwise unserviceable sitting there under the saddle. Same goes for tubes: I carry two plus a patch kit in the seat pack under Debbie's saddle and when ever I need a tube I pull from the seat pack first, then backfill the seatpack with a fresh tube from the shelf.

Spokes are in the same boat. I have made a habit of keeping a few of the old spokes from every wheel I have built or rebuilt; old & new, which I keep in my tool box. I'd estimate that over 20 of those spokes have been given away or used to fix other people's broken spokes on tandems over the past ~7.5 years. So, again, having spares in the right size for your tandem IS a good idea. Since taking up tandem riding, I have kept the correct size spokes for our tandems stashed inside of Debbie's seatpost. They are inserted into and held in-place in her seatpost by one large and one small rubber stopper: the small one goes into the seat post and keeps the ends from rattling around and the large one fits snuggly in the open end of the seat post to keep them from falling out and down into the seat tube.

As I learned long ago in the Boy Scouts, "Be Prepared" ... it think it may have been the forerunner to "Just do It".

[Brian]

This is totally off topic, but I went for a ride in the bush today, and saw a kangaroo cross my path not 10 metres in front of me. If I flatted both tires it still would have been a great ride!

[OldShacker]

I found that the long air pumps (high psi units) work best for how we ride. It only takes a few strong pumps to get it at 120 PSI. The smaller pumps make me look like a monkey doing something ..... I have one or 2 new tubes ready to be put in place and some patched ones just in case. Since we stop to assist others the pumb is just easy to work with. Here in Ohio you have to change a tire really fast or you get eaten up by insects. I have it down to this, Back tire is only 2 bites and front down to 1 bite. The Co2 units work best on my commuter bike. I also use that fix a flat sticky stuff in most of my tubes. It works even at 120 psi. And another item is the tuffys tire liners thay work too ;)

[zonatandem]

Use the Topeak Mt. Morph: light, converts to mini-floor pump in seconds. 100 pump strokes puts in 100 lbs in a 700x23 tire. We're happy with that one!