Why is there a bulge on my bicycle tire when I inflate it?

After replacing a bicycle tube, I experienced a problem: When I inflated the tube, there was a bulge near the valve stem. I couldn’t figure out how to get rid of the bulge. I thought that maybe I hadn’t seated the tube properly, but no amount of reseating made the bulge go away.

A bicycle technician explained to me that I was getting the order of operations wrong.

The order of operations for replacing a tube is

1. Insert new tube.
2. Inflate.
3. Secure valve stem nut.

I had gotten the last two steps in the wrong order: I was tightening the valve stem nut before inflating.

It seems that the Internet tells me that the bicycle technician was wrong, and the valve stem nut should be secured before inflating, since it prevents the stem from going into the rim.¹ I don’t know who’s right, but changing the order of operations fixed my problem, so that’s what I’m going to keep doing.

¹ And the Internet seems to feel that the nut is superfluous.

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