Like myself, I'm sure alot of us have multiple bikes in our stable of materialstic necessaties. I just bought a brand new set of wheels (NEW Fulcrum Racing 5) just as a backup in the event of crash, damage, etc.

What particular component would you choose as an insurance type back-up for serious recreational riding and staying to a committed program??
BTW, could be anything off the bike also, clothing, accessories.

Chains, cables and tires

You already have 2 bikes? Just tubes & tires - and anything else you know you are going to replace like maybe chain or bar tape, if you see it on really good sale.

Enough clothes to ride 2 days in a row in any weather without doing laundry.

For anything else, just ride your other bike until the parts come in.

I have a stash of all consumeable parts- tires, tubes, chains, cables, bar tape, headsets, cassettes, chainrings, spokes. So I don't have to make it to the LBS today in order to fix the bike tonight so I can ride again tomorrow. I also have a rain/backup bike but in the winter I don't want to ride the good bike in the rain.

My backup bike, wheels, etc are old race bikes or parts from them.

I am so relieved that this is not about back-up barz.

I would add helmet to the list btw.

I forgot cleats!

I keep extra cleat screws and an old cleat in the tool box that I take to races.

I keep my old helmets and use them as backups. I once accidentally ran over a helmet with a truck, as I was leaving for a ride. I did the ride with no helmet but it felt very odd.

Actually that's a good one, must buy another, gives me a reason to purchase that Mavic Plasma SLR helmet I have been OOoohhhing over.

Always have two bikes, multiple wheel sets, chains, tubes, bar tape, clincher tires, tubular tires and glue, cleat hardware kit need to order another cassette to keep on hand.

I've got a back up bike, so if anything major goes wrong, on short notice, I would just grab the back up bike.
But I've got back up tubes, tyres and wheels. And if push came to shove, I'd use an old helmet and old cleats on an old set of shoes.

Whew, me too. I was very afraid to click.

Back up bikes for me. Even when I didn't have back up bikes at least a backup wheelset is necessity IMO.

Also cables, tires, tubes. I get tubes in 5-packs, have three extra road tires and a couple of MTBs ATM.

I also have a back up bike for my back up bike.

cleats for sure
brake pads
bar tape
cables/housing
favorite saddle if spendy, discontinued, etc...

my 2nd helmet has a lighting system on it, which is great for winter

Cleats, brake pads, tires, tubes, chains, cables and housings, bar tape.

If you're feeling spicy add a cassette in there. Otherwise just buy it if it fails. You can usually get whatever you need within a day anyway.

Just saw a saddle mention. A+ to that. Once you find a saddle that actually works for you buy up every single one you can find. Things happen. Saddles get discontinued. Your ass will appreciate it.

If we go on a ride that starts away from home, like in the mountains, first thing we grab is a spare wheel and tire set. Your trip could end permanently without one.

Tubes and I can throw on an old tire in a pinch, but I don't specifically buy backup tires.

Yeah. I'm a classic Flite fan. I know these have been reissued, but if I find one cheap in good shape I'll usually buy it.

I bring with me on training rides and to races a spare dropout among other things. It's so easy, so small, so light, and yet you're so screwed if your dropout breaks on a ride. I do bring a chain tool also because of the same reason. We pushed a teammate who broke a chain, 10 miles, over some very small hills. No biggie we thought but it was really hard.

In my gear bag I have extra cleats, pedals, misc tools. I bring a second helmet and try to bring spare parts for my shoes. I usually stick other spares in my gear bag too. Most of the other stuff I can borrow at the race. I've lent/given out bar tape, tubes, cleats, even pedals at races. In one particularly eventful race I lent my whole bike to someone whose bike half fell of their roof rack (broken fork) and lent my spare front race wheel to another racer who flatted their front tire (and she rode her bike to the race). My bike won and my front wheel got second.

I like the Titanio 2000 saddle. Discontinued at around that year. I'm down to three I think. Maybe four.