I do use my multitool. I'm always fiddling with adjustments on my bikes. Also, the part that I've really needed once or twice has been the chain breaker, which has gotten me home after dropping the chain and bending a link. Not often at all, though.
Another note - this can serve just fine as the only chain breaker you own, so if you don't already have one, consider it.
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Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."