The last device Jane had to try was very different.

Adam took her out into a closed courtyard where there was a small racetrack laid out in concrete, weaving its way between small trees and bushes planted in raised beds, with a clearly deliberate pattern of humps and ribs cast into its surface. Beside the track were a couple of three wheeled bikes powered by naked slave girls.

They had bicycle-like handlebars with twist grip controls and bike-like saddles but these were mounted over light tubular metal frames containing the bodies of the girls which were stretched out beneath them and strapped firmly in place. The bikes had two wheels at the front and a single drive wheel at back with pedals connected directly to its axle to which the girl's feet were strapped. The girls' arms reached straight down from their shoulders and clasped the shaft connecting the front wheels which were steered by coupling rods linked to the handlebars by gears and twin steering rods that passed down on either side of the girls' necks where their heads protruded between them. The girls' breasts which dangled freely beneath them were bound about their roots by metal bands which were connected by gear cables to the bikes' twist grip handles. Footrests for the riders extended down from the main frame. The bike like saddles rested just over the girls' naked buttocks. Jane had assumed they would be for men to ride but to her surprise they had large dildos screwed to them which it jutted up vertically.

'These are used for slave bike races and to teach slave girls what it feels like to control other girls,' Adam explained, leading her across to the bikes. 'And of course there are slave owning women who enjoy the sensation of riding them while impaled...'

Jane gaze down at the pretty blonde woman contained so perfectly and yet helplessly within the frame of the bike before her. She saw there was a rod curving down from beneath the saddle which penetrated her anus and another rod rising up from the frame that she straddled bearing a dildo that passed up into her vagina. She was doubly impaled! She could not ride another woman like that! But she feared Adam's anger even more.

Meekly she allowed him to un-cuff her wrists and then she clambered onto the bike and settled down, feeling the dildo slide up her by now aching vagina. She rested her feet on the footrests. It was a little like being astride a motorbike, but there were snaphooks attached to both the handles and footrests which he fastened to the rings of her cuffs, securing her in place. Her freedom was very limited.

'You steer as normal and the break handles work the front and rear wheels in the usual way,' he told her. 'The right-hand twist grip is the accelerator and the left works the gears as marked. Twisting the accelerator pinches her breasts - the bands cuffed about them are spiked in the insides - and she knows she's got to pedal faster.' He patted the bike girl's head where it protruded from between the steering columns of the handlebar. 'Don't worry; she's used to being used like this. It gives her a chance to show how strong she is.'

Jane had noted the girls' muscular looking buttocks, thighs and calves but it did not make her feel any better.

Adam moved to the other bike, unscrewed the dildo mounted on its saddle and sat astride it.

'I'm going to follow you round to make sure you don't slack. If you don't go as fast as you can then it's the breast mangle again for you, do you understand?

Jane nodded fearfully. Gingerly she turned the accelerator handle and felt the girl begin to pedal beneath her. She steered the bike onto the track. Adam followed on behind her. He must have a nice view of her bare buttocks straddling the saddle and the equally bare and anally impaled buttocks of her living engine as they pumped away under her, she thought. She turned the accelerator further and the girl speeded up. And then they hit the first of the bumps.

The jolt was transmitted up through the bike frame into the dildo on which she was impaled, making her gasp. Then the bike passed over a grid of fine ribs cast into the concrete and the vibrations set the dildo almost buzzing within her. And then she realized that this would be as much an ordeal for her as for her living engine. It was impossible from a woman to ride a bike like this without getting aroused. That was the Irontown way...

'You can go faster than that!' Adam called out from behind.

With a sob Jane moved up a gear and twisted the accelerator hard over. Her living engine responded smoothly, her strong thighs pumping even faster. But with greater speed the impact of every bump and rib was magnified, setting the dildo trembling and pumping within her ever hotter and wetter cleft. Jane whimpered as she struggled to concentrate on her steering and keep the bike on the track.

'Faster!' Adam shouted.

Jane moved to the highest gear and wailed and bit on her gag ball as the bike seemed to come alive between her legs. But then it was a living thing, or at least a fusion between a living thing and a machine. And she was riding it: in charge of it... it's master...

Round and round the track they went. She saw the faces of visitors looking out through the ring of enclosing windows at them. What a spectacle she must make: a naked woman riding another naked woman. She hoped they understood that she was only doing this only because Adam was making her.

Of course they probably didn't care. Here this was normal. They liked watching naked women and machines working in harmony and right now she could hardly be any closer to the girl between her legs...

The orgasm caught Jane by surprise and she almost crashed into a tree as she swerved off the track and came to a skidding halt, doubled up in her saddle as she jerked and ground her hips in helpless desire and desperate release. Some of her ejected juices overflowed the saddle and dripped onto the naked sweaty haunches of her living engine, who beneath her was working her hips about on the double dildos that impaled her. Was that her reward for enduring such degradation?

Adam pulled his bike up beside hers and reached across and patted her sweaty bottom. 'Now you're getting the idea,' he said.

She'd had a taste of using another girl's muscle power for her pleasure and, for a fleeting moment, it had felt frighteningly exciting.