Bicycle riding and a sore bottom.

I cannot really help you with how to prevent this in the future or help you to understand exactly why it happened. If something hurts so much that you feel that you have been injured then yes you should avoid that activity until the soreness goes away. Continuing to ride will only keep bruising where you are already hurt and it could make the healing process take longer.

 

Depending on how long you were on the bike for, this is fairly normal when you first start cycling and should go away fairly quickly. Take a few days off between rides (or just stick to very short distances) and you'll build up tolerance. It's worth trying different saddles to find one that suits you, as some are more comfortable than others (and more padding does not necessarily equal more comfortable), and try to avoid clothing that has bulky seams where you contact the saddle.

 

I couldn't agree with @Broccoli any more... Regardless of whether or not I've received as a bottom in sexual activity recently, my butt still hurts when I sit on a bicycle and cycle after not doing it for a while, regardless of the bicycle, seat cushion, etc... This is coming from someone who cycles regularly as my main source of exercise.

Considering this, I'm not sure your discomfort is a result of you and your friend having sex.

The only question I cant think of is, how often do you cycle?

 

I wonder if this soreness is more to do with you having sex than riding your bike. It sounds like everything was fine until you bottomed on Friday night with your friend, and only since then you have found it painful to get on the bike and go for a ride. The quote below seems to confirm what I am thinking:

Are you sure you used enough lube before getting down to it? You should only experience pain when being entered if you haven't lubed up properly. The fact that your friend lasted only a few minutes suggests to me that he was going at a fair pace, so if you hadn't lubed up adequately there is the distinct possibility of internal micro-tears which you wouldn't necessarily see. When you are riding a bike this pain might be aggravated.

If the pain doesn't subside by Monday I would suggest visiting a doctor and I would strongly recommend no more sex this week or weekend.

 

Are you wearing padded cycling shorts? (You can get cycling shorts that look just like normal shorts if you're worried about the skin tight ones) Getting the right saddle and having the right shorts made a huge difference for me (and that's as a cis woman). If it is the cycling, there is some amount of just having your body adjust, but having the right equipment does make a huge different. And more padded isn't always better as far as the saddle. I found there was kind of a sweet spot for comfort. I did, in fact, have a lot of butt soreness when I first started riding, but now I can do 3 hour rides and it not be too too terrible.