Sensors in the handlebars, seat cushion, and pedals indicate the presence of a rider and signal the control rod drive mechanism (CRDM) in the bicycle seat springs to activate. A handy thermostat near the handlebar grips allow the rider to select the desired temperature by metering the CRDM. A compact pump in the pedal bearing housing circulates the reactor coolant throughout the frame, including the handlebars. After 87 years of faithful service, simply swap out the plutonium-238 in the bicycle seat, and you (or more likely, your heirs) will be ready for more biking fun.
As a bonus feature, a smoke detector is included at no extra charge which will alarm loudly should it detect that your Speedo Bike Shorts have somehow caught fire.-- Grogster, Dec 16 2012 Not even vaguely related... Bicycle_20Seat_20Shorts [normzone, Dec 16 2012] Pu-238 isn't fissile … we sense a misunderstanding on your part as to the physics of radiothermoelectric generators, which aren't reactors and don't have control rods.
Also, placing the isotope package in the bicycle seat will (unless massively shielded) rapidly ensure that you have no further offspring, and shortly thereafter leave any you already have gleefully contemplating how much they've just inherited.
You can't change the output of such a generator, which is maximal at the time of manufacture and steadily decays over time. That's why they're used to cover the baseload for satellites and deep-space probes, when photovoltaics may deliver intermittent (but predictable) output. Batteries are usually used to cover surges in load, like when the main transmitter is active. Under low load conditions, surplus energy has to be dissipated by a simple resistive radiator.
Bun for a design potentially lethal to cyclists.-- 8th of 7, Dec 16 2012 //likely, your heirs// unlikely; and yet more unlikely that if they exist, they'd be of a bicycle-fitting shape-- lurch, Dec 16 2012 Can we have a new [MFD] for "nuclear powered everything"? I've got one: a nuclear powered toaster. No, nuclear powered TV! Nuclear powered Christmas tree lights?
I read this as an actual reactor [8th], not an RTG.-- DIYMatt, Dec 16 2012 Because Pu-238 isn't fissile by slow neutrons, but it is used in RTGs. Unless the proposal is for a bicycle-mounted FBR, which would be ... interesting.-- 8th of 7, Dec 16 2012 Start with a nuclear powered LED.-- pashute, Dec 17 2012 Ironically, an everlasting light source based on radioactive material and phosphor is probably quite practical …-- 8th of 7, Dec 17 2012 how is that ironic ?-- FlyingToaster, Dec 17 2012 //Ironically, an everlasting light source based on radioactive material and phosphor is probably quite practical//
That's why it's quite baked, and I have one on my car keys. It isn't exactly "everlasting" but it will glow for 12-20 years.-- DIYMatt, Dec 17 2012 random, halfbakery