Most people carry way too many useless tools. Get the tools you need, put them in a ziplock bag, stuff it into your saddle bag and ride. We are talking about fixed gear bikes, right?
Even the multi tools contain too many useless bits and pieces, too much extra weight and cost too much. Using the Crank Brothers M19 for example (no offense, just using it as an example), from what I can tell it has 7 Allen wrenches, two Torx bits, two Phillips head screwdrivers, a flat head screwdriver, a chain tool, the metal frame which holds it together and the stainless steel carrying case.
I would throw the metal case in recycle bin on the first day and then I would take the thing apart and do the same with the metal frame. I'd replace all of that with a ziplock bag. Use two bags if you are worried. That alone would probably save half a pound.
The Phillips head screwdrivers are useless on a well maintained modern bike. My bike has a few small Phillips head screws which hold the SPD cleats to the pedal body. These I cemented in place with blue Loctite and they will never come out until they need to be replaced many years from now. Give the Phillips head screwdrivers to your buddies with derailleurs and save the weight.
If you have any other Phillips head screws or Torx fasteners on the bike then replace them with Allen head screws. Done.
Flat tip screws? Really??? This isn't wood shop.
3mm, 4mm and 5mm Allen wrenches will cover the seat clamp, seat post clamp, chain ring bolts, stem, brake caliper mount, brake cable clamp, brake pad mount and brake lever mount. The bigger bolt in the center of the cranks is unlikely to come apart and if it does then an Allen wrench probably isn't going to help you.
The chain tool on the M19 actually looks like a good idea with integrated wrench. I don't carry a chain tool but I maintain my chains meticulously and change them often.
Instead of a heavy, expensive multi-tool with a bunch of stuff you are never going to need, why not ride down to Sears and buy some Craftsman 3/4/5 mm Allen wrenches and a stubby 15mm combination wrench? Tire levers, patch kit, spare tube, pump or CO2 cartridges and a folded dollar bill for the inside of the tire when you get a hole are the only things else most riders are are ever going to need while on the road. This is all I carry.
As IAmSam correctly said, a well maintained bike should not break often. A tool you don't know how to use might as well be left at home. As for fixing other riders bikes, the rest of the peloton can carry their own tools.
-Tim-
Last edited by TimothyH; 08-17-15 at 05:35 PM.