The Chainlink

What Tools Do You Carry for Bike Repair When You Ride? * * * (Update)* * *

A while back a fellow cyclist stopped me to ask if I had some tools(I had my bag on the bike)so he could adjust things on his road bike. Seat tightening & etc. He carried NO tools at all ! No backpack, nothing. He became a bit unhappy because I could not totally help him with the tools I had. He 'thanked' me, and then moved on. So, basically, what tools and supplies should a cyclist ALWAYS carry ?


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Very cogent, Mr. Oxnard!
Reboot Oxnard said:

The math is complex but the key to the question about using air versus CO2 to charge an inner tube lies in the molecular weight of the three gases. Reduced to simple terms, the heavier a molecule is, the larger it is and the larger it is the more slowly it will permeate/effuse through a substance.

Air is comprised of approximately 79% N2 and 21% O2. There is a smattering of other stuff in it but not enough to make a difference. Both N2 and O2 are lighter/smaller than CO2 which tells you that, all other things equal and constant, CO2 will diffuse more slowly than air. If your experience is that it doesn’t, that is that your CO2 inflated tires are losing pressure faster than air inflated tires, something else is changing that is disproportionally affecting the permeation rate. The biggest variant is the water that is in air: as it heats up it expands more than any of the gases and that increases tire pressure. Of course, at the end of the day, your air filled tire is going to deflate more as the water cools.

Gas = Molecular Weight
CO2 = 44.01
N2 = 28.0134
O2 = 31.9988



Reboot Oxnard said:

The math is complex but the key to the question about using air versus CO2 to charge an inner tube lies in the molecular weight of the three gases. Reduced to simple terms, the heavier a molecule is, the larger it is and the larger it is the more slowly it will permeate/effuse through a substance.

Air is comprised of approximately 79% N2 and 21% O2. There is a smattering of other stuff in it but not enough to make a difference. Both N2 and O2 are lighter/smaller than CO2 which tells you that, all other things equal and constant, CO2 will diffuse more slowly than air. If your experience is that it doesn’t, that is that your CO2 inflated tires are losing pressure faster than air inflated tires, something else is changing that is disproportionally affecting the permeation rate. The biggest variant is the water that is in air: as it heats up it expands more than any of the gases and that increases tire pressure. Of course, at the end of the day, your air filled tire is going to deflate more as the water cools.

Gas = Molecular Weight
CO2 = 44.01
N2 = 28.0134
O2 = 31.9988

That's only true if all the gasses have the same permeability in the material in question.   CO2 is more permeable in butyl rubber so it diffuses more quickly through tubes despite having a higher molecular weight.

Permeability of Various Elastomers to Gases at 25°C Relative to Natural Rubber Gum Vulcanizates (=100)5

Elastomer He H2 O2 N2 CO2 Air
Silicone Rubber - 1070 2200 3300 1600 2700
Natural Rubber 100 100 100 100 100 100
EPDM - - 88 80 66 83
Polybutadiene - 86 82 80 105 81
SBR 74 81 73 78 94 76
NBR (80/20 butadiene acrylonitrile) 55 51 35 31 48 33
NBR (73/27 butadiene acrylonitrile) 39 32 17 13 24 15
Polychloroprene - 27 17 14 20 15
NBR (68/32 butadiene acrylonitrile) 32 24 10 7.5 14 8.5
Butyl Rubber 27 15 5.6 5 4 4.8

Properties of Butyl Rubber

Can you provide an explanation or source for how butyl rubber is more permeable to CO2 than N2 or O2?


S said:

That's only true if all the gasses have the same permeability in the material in question.   CO2 is more permeable in butyl rubber so it diffuses more quickly through tubes despite having a higher molecular weight.

The problem is that the table you're looking at normalizes the permeability of the gases at 100 for natural rubber.  This makes comparisons of the permeability of different gasses impossible but does let you look at the permeability of a gas in various substances.

Check out the tablehere to get actual permeability numbers and you'll see that CO2 is a lot more permeable than O2 by a factor of 3-6 times.

Reboot Oxnard said:

Permeability of Various Elastomers to Gases at 25°C Relative to Natural Rubber Gum Vulcanizates (=100)5

Elastomer He H2 O2 N2 CO2 Air
Silicone Rubber - 1070 2200 3300 1600 2700
Natural Rubber 100 100 100 100 100 100
EPDM - - 88 80 66 83
Polybutadiene - 86 82 80 105 81
SBR 74 81 73 78 94 76
NBR (80/20 butadiene acrylonitrile) 55 51 35 31 48 33
NBR (73/27 butadiene acrylonitrile) 39 32 17 13 24 15
Polychloroprene - 27 17 14 20 15
NBR (68/32 butadiene acrylonitrile) 32 24 10 7.5 14 8.5
Butyl Rubber 27 15 5.6 5 4 4.8

Properties of Butyl Rubber

Can you provide an explanation or source for how butyl rubber is more permeable to CO2 than N2 or O2?


S said:

That's only true if all the gasses have the same permeability in the material in question.   CO2 is more permeable in butyl rubber so it diffuses more quickly through tubes despite having a higher molecular weight.

+100. A pump never runs out of air.

also, a full-size frame pump is a much better farm dog deterrent than a CO2 cartridge or even a mini pump.
 
peter moormann said:

I ve helped many people on  the roads over the years  with  broken or flatted bikes.

I always talk to them about repair stuff whe Im fixing their chain or flat ....

Most of the time they seem to have no mechanical aptitude to be able to fix the problem with their bike.

I'm seriously amazed when I run into a middle aged cyclist who can not fix his flat tire on his aero bike.

So the point of carrying tools, patches, spares is dead weight for them.

CO2 cartridges are useless when they are empty.

How do you refill them....... with a compressor or  a pump?

My pump never  runs out of compressed  air....even to max pressure.

Amazing?

Pumping since '72 etc etc etc.


rwein5 said:

I'm amazed that anyone still uses a hand pump for on-the-go air needs anymore.

They are so vastly inferior to CO2 cartridges on almost every metric, including size, max pressure, speed, etc etc etc.

I carry a Topeak Master Blaster frame pump, a seat wedge with the following items: 1 spare tube, 3 tire levers, 1 Park multi-tool, 1 pair needle nose pliers for when I have to replace a cable, a Park spoke key to touch up my spokes, 1 Clif Bar wrapper which can come in handy should I gash a tire, and a patch kit.  Also, a cell phone, a Swiss Army knife, a Visa card in my wallet and change.

For my suburban commute:

Rode bike commute:

[a 4mm allen, a 5mm allen, spare inner tube, co2 (2)cartridges (I get the ones with foam on the outside) & screw-on style device, mini presta air gauge, plastic tire levers (2), presta adapter]

Foul weather commute (converted MTB):

[folding metric key set, spare inner tube, Mini-pump with gauge, small screw driver, plastic tire levers(2)]

Always on me [knife, wallet, cell phone]

I agree, I like the co2 on the road bike but it takes some skill to use. One or two mistakes and you're out of gas! I'm a good mechanic but once I was in a bit of a hurry and I inflated before setting the tire right and I had to deinflate (all Brady jokes aside) to re-set it. I ended up with the last leg of my commute being really slow to avoid rim damage on a under inflated tire.

J. W. said:

+100 Co2. Just saying. I pump before leaving home. On the road, I prefer to get rolling again asap.

#toeachtheirown
Regarding co2 and Butyl rubber. There does seem to be less permeability but chemistry is also at hand. Does it matter? Probably not by much. co2 has two oxygen atoms to one carbon. So if you inflate with pure co2 you may actually have more oxygen exposed to the butyl. The question is: is the butyl effected by the co2 over time. I'm reasonably confident that over one days time the issue is insignificant. So if you are worried about it, replace the co2 with air when you get home.

So, I've got to thank Tom A.K. for updating this thread.  It reminded me to head over to Boulevard Bikes and buy a few more charges yesterday.  I ended up using one last night!

I've got a pedicab and was halfway through a ride when I realized I had a flat.  I hopped off, hit it with the CO2 and finished the night (very slow leak).  I had the 16oz charge and nozzle in my coat pocket, didn't even have to ask the passengers to get up to access my tools, let alone cut them loose and lose the fare.

I do carry a Road Morph frame pump, but the trike has 26" x 2.5" tires that take over 100 pumps from a MUCH larger floor pump to bring up to 80psi. 

At approximately $2 each, it is conceivable that I might go through a handful of them just to keep rolling for an hour at a busy event rather than stopping to change the tube, disgustingly wasteful and greedy capitalist that I am.

Consciously or not, the decision to carry any given tool is based on a simple assessment: usefulness vs. weight. 

While a 4mm allen key might not be something used frequently, I would argue that carrying one isn't going to slow you down. 

Duppie, Apie described a scenario below that was NOT preventative maintenance-- straightening bars out after a crash.  You seem to be arguing that he doesn't need to carry tools;  not everyone's commute has the luxury of a bikes-allowed, reasonable CTA alternative, of traveling at hours when such service is available and of riding a bike that is allowed on CTA.

[I edited my first post, I think Duppie misunderstood the scenario below?]



Duppie said:

Bikes absolutely require maintenance. But what you describe is corrective maintenance. It is done after the failure (loose headset) happened.

Periodic preventive maintenance will minimize the occurrence of unexpected failures. I put all my bikes on the stand yearly (or more often if I use it alot), and check out all areas I know. Check the tightness of screws, and adjust if needed. It all takes but a few minutes each time.

As a result, I cannot remember the last time I had a failure that required roadside repair during my commute. (one exception of course being a flat tire, which even with the best maintenance is sometimes unpreventable).

That is why I don't carry any tools. I have found no need for them. And when I get a flat, the CTA is a more than adequate backup for me.

Apie (10.6) said:

A few times.  After an accident, or just being loose after 1000's of miles on many different surfaces.  I can't believe i'm even answering that question.  Bikes need maintenance, if you use them. 

Duppie said:

How often does your headset loosen in the middle of a commute?

Apie (10.6) said:

This: http://www.amazon.com/Park-Tool-MT-1-Rescue-Wrench/dp/B000OZ9WTQ/re...

2 tubes (in case I have another flat on the way home)

a pump.

2 tire levers

You can zip tie or rubber band it all together.  If I am going on a longer ride I bring a patch kit and a phillips.  If my chain breaks?  My ride is over.

If you have a long commute, its a lot quicker to have an allen key and tighten your headset or brakes then taking the bus.

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