I hid a vibrator in the seat of my stepmom’s exercise bike

My stepmom Diana has pretty much always been in my life. She married my Dad, Patrick, when I was young, five years old to be exact.

The whole time I’ve known her as far back as I can remember she has been a quiet, mousey mom-figure in my life. She is never too overbearing, never yells at me, never grounds me, nothing. If I ever did something to upset her, she would leave the room with a disappointed sigh instead of trying to control me.

I remember purposefully testing her patience over and over, yet she never cracked in front of me. She would shake her head, turn away from me and then disappear to another room. Yes, I did try following her a couple times to continue my annoyance. During those attempts I was met with her stone cold face and silence. The lack of emotion did its job to scare me away.

I stopped being a menace to Diana when I was a bit older. We got along better and she continued to be a supportive stepmom, doing laundry, cooking, cleaning and pretty much all the other household tasks.

Everything changed one summer when I was back home from school. I was playing a lot of video games since I had so much downtime, and Diana had recently started riding a new exercise bike my dad bought for her.

To set the scene, our house had an entertainment room with a large movie screen and projector. Naturally that’s where we would play video games too. So when I got a PC, I set it up in the entertainment room on a desk with two monitors. When my Dad bought Diana the exercise bike, he set it up behind the giant U-shaped couch in the entertainment room so she could watch the movie screen while riding her bike.

During that summer I played video games almost everyday, mostly in the mornings and evenings. Diana would come in and put something on the movie screen then set up her things for her workout. The majority of the time she wouldn’t say anything to me during her workout. Probably because I was in the back right corner of the room, with my desk facing the wall, headphones on, focused on my screens, clicking away. Her exercise bike was on the opposite side of the room but directly behind me.

The exercise bike happened to be in the perfect position for me to see her reflection in one of my monitors. When the screen was black, I could see her reflection in sharp detail. And even when it wasn’t black, I could still make out her reflection.

Diana would ride at different paces, sometimes going her hardest and other times going at an easy steady pace. When she rode fast, she would lean forward and put her elbows on the handlebars. Consequently, her ass stuck out and I would have an amazing side view of it. The arch in her lower back was especially sexy when she was pushing hard. Her hips would tilt forward and rock side to side while she pedaled.

She wore athletic shorts and a tank top generally. Sometimes if it was cold in the room in the morning, she would keep her jacket on. I got to know her routine pretty well.

After seeing her ride almost daily for a month, I thought of a devious idea. What if I put a vibrator in her seat? Would she feel it? Would she be suspicious? If I only used the tiniest amount of vibration, she might blame it on the exercise bike itself. The idea turned me on a lot thinking about it, so I said fuck it, let’s do it.

I bought a remote controlled bullet-sized vibrator the next day. That night, I pulled her seat off the bike and peeled back the fabric underneath the front of the seat, inside was foam cushion. I cut a small slit into the foam and fit the vibrator inside. I closed it all back up with glue so that the seat looked completely unchanged.

I tested my creation with the remote control. At the lowest vibration setting, I couldn’t feel it. I pushed two fingers hard into the front of the seat and finally I could feel the vibrator moving inside the cushion. Mounting the seat back on the bike, I even tried sitting on it myself. I couldn’t feel anything.

Well that was good to know. The lowest vibration setting wasn’t even noticeable. I turned up the intensity until I could barely feel it and noted the amount. Then I tried turning it to the max setting and it made me instantly jump right off the bike. It worked better than I thought it would.

The next day my dad was away for work and I was playing a solo RPG. Diana came in around 11am to exercise. I waved at her and said hi. She was wearing something similar to a tennis skirt and a white tank top. She said good morning in response.

After getting situated, she started riding her bike. It was impossible not to constantly watch her reflection. Diana was extremely fit and showed a lot of muscle tone. Greatest of all her assets though was her ass. It was a perfect curve, developed shape, and big enough to bounce around when she walked. Eagerly, I waited for the perfect moment to start the vibrations.

Part way into her workout, she upped the intensity and started leaning forward. So I upped the intensity too and started the vibrator, though at the lowest setting. My heart raced as I watched her pedal. She didn’t react. Diana kept her pace steady and continued to watch the movie she had put on.

For reference, the intensity setting goes from 0 to 100. I had it at 5 currently. When I had tested it, I had started to feel the vibrations around 15.

I left the setting at five for a while, wondering if she was more sensitive than me and could actually feel it. Her rhythm and form looked the same. From what I guessed, she wasn’t feeling the vibrations. So I took the setting to 10.

For a minute or two, she kept the same pace, but then suddenly, she began going faster and leaned forward even more. Diana kept her head down and pedaled. I intently watched her reflection.

After only a couple seconds, she glanced over at me. My blood went hot. Did she notice? I kept clicking away at my game and did my best to seem totally enveloped. It was just a glance though, like she was checking to see if I was paying attention to her.

Now Diana looked down at her bike instead of the movie. Oh fuck she totally noticed something was up. She seemed to hesitate for a moment… but then quickly got back into her rhythm. This time though, as she pedaled hard, I noticed her hips were pushed forward just a little bit more. I could see her riding closer to the front of the seat and the slightest extra arch in her lower back.

She kept going. I was trying so hard to act normal but I could see her reflection pushing harder and harder. Her motions became more accentuated and her hips rocked side to side on the seat. Diana had never been this expressive before on any of her rides.

She was going at her fastest pace and I could tell, she felt it. There was no way she didn’t judging by her motions. Well there was only one way to be absolutely certain. I took the setting to 15.

She had been pedaling her hardest for longer than normal at this point. Again, I saw her glance in my direction. I kept my chair facing away from her and gamed away. Diana put her head down and focused. Her hips moved faster than normal, grinding herself into the front of the seat.

She was breathing hard but started to take even bigger and bigger breaths… and then her legs started to shake. They pushed outwards and twitched like she was losing her strength. I held my breath.

Diana shook and started grinding herself hard into the front of the seat. Her breath caught and she twitched forward, her whole body seeming to curl up. All the while she pedaled.

For about ten long seconds, I was making my step mom cum on her exercise bike. She looked so fucking hot. When she finally began to relax, her pace slowed and I made sure to dial down the vibrator setting accordingly. She went at her cooldown pace for about five minutes, the whole time, glancing over at me constantly. It started to make me nervous but she was probably wondering if I had noticed. My headphones were on though and I hadn’t turned around the whole time.

Once Diana finished her exercise and hopped off her bike, I could tell she was having a little more trouble walking this time. She gathered her things and left the room, and I finally took a breath.

This was the first time of many that I made her cum while she exercised. Let me know if y’all are interested in what happened after this.