Originally Posted by
Jsosborn
Thanks for all the input. I service my own bikes, as do the others with me. I’ve got all the usual spares and the tools to replace them. Each bike has a spare chain, cassette, tire, tubes, brake pads, and pedals. I’m probably bringing my portable bike stand as it packs small. We’re using a 4 bike hitch rack, and the roof rack is just for clothing and personal effects. That leaves tools, drinks and food in the back so access is simpler.
That is more spares than I'd take, but no harm if you have the space and already have the parts. I've had a chain last for a full coast to coast tour and then some. Mine have generally lasted the equivalent of more than two coast to coast trips. I'd never expect a cassette to fail catestrophically or wear out mid trip. Same for pedals. Only once ever had a pedal issue and that was a little looseness in the bearing that I could limp along with. The shop I was near didn't have the tool to work on it so I bought new ones rather that put up with the slight wobblle.. Later I rebuilt them and reassembled them. They are still going strong. They were from the original 1990 vintage SPD model and now have a huge amount of mileage on them including tons of muddy single track from service on my MTB and at least one coast to coast tour from their time on my touring bike. I think they were repacked with new grease twice I don't know the mileage on them, but it is considerable. I have had cheap pedals fail early, but good pedals seem to last forever.
If your experience is that you need to replace that stuff more frequently then by all means carry it all. Personally I probably wouldn't or would share the spare inventory carry fewer spares to be shared among the group. After all you can buy stuff on the road or have it shipped to you. I know that our group of three never needed a chain, pedal, or cassette during the tour. In fact those all lasted for a lot of future riding and some more tours. In any case when/if they did fail they didn't do so catestrophically.
By all means carry a tire or tires, plenty of tubes, and brake pads. Oh, and some spokes. If your bike has a replaceable deraileur hanger it might be worth getting one and carrying that.
Having someone at home who knows what and where stuff is can be a help. That applies to gear other than the bike. You may find that you want have stuff sent from home that you wish you had taken via general delivery or want to send stuff home that you are either done with or find you don't need. With a support vehicle sending things home is less of an issue, but even then you may find you get snowed under a bit with too much stuff. Simplifying by sending home gear you won't need again could be worth doing at some point.
In any case you have to draw the line somewhere. If you are carrying a cassette, then what about other stuff that is just as likely to fail. Derailleurs? Brifters? If those then maybe bottom bracket, crank, hubs, rims and on and on. I am not seriously suggesting carrying those, but my point is that there is always something that can break that you won't have. The odds are very good that you won't need any of them and if you do you will definitely be able to get by some how especially since you have a support vehicle to run to the closest source for the needed parts.
I don't know how compatible your family's bikes are for parts sharing but sharing should limit the need to carry all the parts for each bike. If you want to take something extra that would really be helpful, have the space, and if there is compatibility across the group, a set of spare wheels would be a nice thing to have. It would allow you to delay some repairs and constitute spare tubes, tires, rims, spokes, hubs, skewers, and cassette.