Spares (not tools) for roadside rescue kit to keep in car
 

I keep a spare toolkit in my car and have used it many times to get stranded cyclists back on the road. I know what tools that I need, and I know how to use them, so that is not what this thread is about.

Yesterday, I drove by a cyclist that was hopping to the side of the road with one foot stuck in a pedal. It turns out that he was missing a cleat bolt, and his foot got stuck in the cleat. Fortunately, I had a spare bolt (m5 button head) that worked perfectly and was able to get him on his way.

What spares do you carry in your car? Here is my short list:

several inner tubes of different sizes
patch kit
tire boot
spare tubeless valve w/core
presta to schrader grommet
road brake cable
derailleur cable
a couple of spare ferrules and tips
misc spare m5 bolts
presta nuts
25mm m6 bolt
chainring bolts
9, 10, and 11 speed quick links
square taper crank bolt
Cable ties
bar end plugs (I hate to see people riding without these)
”T-nut” for saddle clamp (if you think that this is overkill, I have seen four different rides ended or made miserable because of a lost seat clamp bolt and prevented one since I started carrying this).
cheap, giveaway flat pedals (for a ride where someone forgot their shoes, this has also happened more than once).

Great list and darned nice of you to help others out.

Some things that come to mind;

QR skewers
Velcro strips in miscellaneous sizes
Electrical tape

Worn out road tires. GP5000 25mm (now I use 28mm, but those don't fit every bike.)
There's a few hundred miles left on the tread, perfect for finishing a ride after a tire is sliced open.

I've never had occasion to use these spare tires in my trunk. I have loaned (empty) water bottles on three different rides where riders forgot their bottles, probably sitting in their kitchen.

good call on the tires. I replace mine with a few hundred miles left, so I can fold one up and throw it in the trunk. I have done that at my work where we have a spares locker in the bike parking area with tools, pump, tubes, etc. lots of my coworkers have used the “tube bank” and everyone has been good about helping keep it stocked.

Most important are first aid supplies to deal with road rash and prevent a subcutaneous infection. Flat tires are what disables a bike and with the wide range of wheel diameters and rim widths there are too many tube sizes to carry.

I already have a first aid/trauma kit in my car. Couldn’t agree more. Main items are tourniquet, Hemostatic gauze, roll gauze, and tubular gauze for that “pro” look.

I used to keep a pump in the trunk mostly for myself but I wouldn't have hesitated to pull over to offer it to anyone to save them from having to use their mini pump.

I can't believe you thought of the square taper crank bolt.

a couple new chains.. i'd carry a couple 6-7-8s, a 10 and an 11 speed... typically chain problems are caused by the chain saying "I'm Done!" and breaking.

a new quiklink won't fix "worn the heck out."

You don't need the exact right tube to get you home in an emergency. I have put a 700 tube in a 26 inch tire before. I carry a 700x 35 tube presta valve stem and an adapter to Schrader and chain repair links in my Topeak trunk bag along with patch kit pump and CO2 inflator. It's in the car when it isn't with me on bike extra CO2 cartridge in the car

I actually do have a couple of spare chains (10, 11 speed for my bikes) in my car, and have given someone a chain from my trunk to get them home, but I probably could have got them home with a quick link and one less gear.

A worn out chain (repaired with a quicklink) should still get someone home, which is really my goal. I would say "a quick link wont permanently fix "worn the heck out". It will get them home.

A new chain is likely to cause problems on that "worn the heck out" cassette.

and broken chains are about as much fun as slugs in your hiking boots at sunup.