My stepmom orgasmed on her exercise bike while I was in the room

Diana came into the entertainment room again the next day to ride her bike. I was already an hour deep into a multiplayer FPS with some buddies and hardly noticed when she came in. My nerves were on edge today though after what had happened yesterday. I was continually doubting myself and what I had done.

She didn't attempt to say hi to me which was expected since I was in game chat with my teammates. In the reflection of my monitor, I watched as she set up her things and got on the bike. She sat there for a moment while she picked out something to put on the screen.

My stepmom was wearing black workout shorts and a blue tank top. Though her shorts mostly disguised the shape of her ass, her top hugged her breasts tightly. Part of me thought I could make out the faint outline of her nipple but it was hard to tell in the reflection.

Diana began pedaling once she had chosen what to watch. It looked like some 90s romcom I'd never heard of. Not long passed before I noticed she had begun to pedal quicker than normal. She'd gotten right to it. Well I better keep up appearances I thought to myself.

Reaching my hand in my pocket, I felt the remote control for the vibrator. I brought it out and looked at it in my hand. Discretely I turned it on and set it to the lowest speed, 5. I glanced back at Diana and I was surprised. She was pedaling almost the fastest I'd ever seen her go. Rarely had I ever seen her go faster.

Fuck, I thought to myself. Is she testing the bike? Hurriedly I dialed the vibrator to 10, then 15 a moment later.

Diana's hips lurched backwards and she slowed down immediately.

Oh shit.

I turned the vibrator off just in time before she sat forward again. She was still pedaling, but going slowly and looking at her seat inquisitively.

There was no backing out now.

Diana looked towards me.

I hadn't been focusing on my game at all and realized I was practically afk. My friends were in my headset calling my name too.

In a hurry I began playing again and responded to one of my friends, "Yeah yeah I'm coming. Don't do anything stupid."

Nervously, I glanced at Diana's reflection in my monitor. She had turned away and was watching her movie while pedaling at a medium pace. For a long moment she stayed at that pace. I was dying inside wondering what she was thinking. My game helped keep me somewhat distracted but my heart was racing inside.

My friends and I were starting another match when I noticed Diana's pace had increased. In response I turned on the vibrator. She looked like she was going fast enough for 10 already so I set it there. A moment later Diana leaned forward and put her elbows on the handlebars. Her hips moved forward until she was positioned right above where I had put the vibrator.

I did my best to stay focused on my game, communicating strategy with my teammates, but right behind me, Diana was pressing herself up against the vibrator that I was controlling. My cock was practically a second heart beat.

Diana rode how she normally would... but there was extra movement in her hips. I could see the arch in her back curling and releasing as she used her core muscles to grind her hips forward and backward. It was plainly noticeable. There was no doubt about it now. Diana rode the front of the exercise bike like she was riding a cock.

Holy shit.

She wasn't over-expressive. She didn't moan or give it away with her face. She looked as normal as could be while riding her bike, except for that small rock in her hips. It went on for what seemed like forever but in reality it was probably only a minute.

I watched in the reflection as Diana switched her grip on the handlebars. The muscles in her arms flexed. She usually kept them relaxed so this was different. Her body curled forward more the slightest amount. It looked like she was almost trying to pull herself down into the seat. She wanted more, I realized.

I set the vibrator to 15. Diana's mouth dropped open and she let out a gasping breath. Her whole body flexed and her hips gyrated even faster. She was clearly going to cum soon and this time her expressions weren't as covert. Her eyes closed and she brought one hand up to her face. Immediately, her hips locked into a slower, longer motion. Her pedaling slowed gradually and that's when her legs started twitching. She was cumming.

I had lost all focus on my game, but I tried my best to keep up appearances. When Diana's orgasm was finally over, she sat upright and scooched back on the seat. I dialed down the vibrator to a 5 and then off. She glanced around the room, eyeing me multiple times. I did my best to seem as inconspicuous as possible.

For about ten minutes, Diana rode at a cooldown pace. Her attention flipped back and forth between her phone and the movie. I expected her to be finished with her workout. This was about how long she usually rode for. But no, Diana put her phone down suddenly and began going faster.

I watched again as she increased her intensity. Her body position shifted and I could tell what she was looking for. I turned the vibrator on and she quickly found it. I never expected that Diana would enjoy my modification this much.

For a second time in the same workout, I made Diana cum while riding her bike. This time was even quicker than the first. It seemed like once she had already been there, it was easier for her to get there again. My dick was leaking precum from being hard so many times.

After her second orgasm, she finished up her workout quickly. As soon as she was gone from the room, I jumped up and headed to the bathroom for much needed relief. There was an attached bathroom on the side of the room where I sat. The door to the bathroom was a sliding barn door, I closed it behind me.

I finished myself off in record time and got back onto my game. It was hard to focus though since the image of Diana cumming was seared into my mind. Not long passed before my cock was hard again and I needed to take another trip to the bathroom. I was deep in this whole situation now and part of me knew it might not end well.

The following day I wasn't around. One of my friends was having a get together and I ended up spending the whole day and night at his place. When I finally got back home, I could tell my Dad was already at work since his car was gone. Diana was here though. I walked into the house and to my surprise, Diana was standing in the entryway. Her eyes were wide and she glared at me hard. It seemed time had stopped between us. Finally, she lifted a finger and pointed at me.

"What did you do to my exercise bike Jack?" she asked forcefully.

Ahhhh fuck me. The gig was up.