Bike display won't come on no matter how much you pedal. What is the problem?

The display (timer) needs to be connected to a sensor on the bike.
Make sure the display is plugged into a cable coming out of the bike.
If it's plugged in and still doesn't work, then contact the manufacturer.

It could be,
1. a bad display. (possibly a broken PCB connection)
2. a bad sensor inside of the bike. They typically use a Reed switch.
3. a broken connection in the cable or connector
4. the magnet fell out of its location.

You can get a replacement monitor from the manufacturer. If this doesn't solve the problem then it's either the sensor or the connection.

You can also place a continuity tester across the 2 contacts of the connector that plugs into the display. The continuity tester should flash when you pedal the bike.

Here's a link where you can purchase a continuity tester.
http://www.amazon.com/Extech-ET40-HD-Continuity-Tester/dp/B0025PK724

You can also pickup a continuity tester at any auto parts store.

your free wheel is shot. it takes special tools to repair it. take your bike to the nearest bike shop

on the spraket there a small spring inside may its damage already.

will the pedals move forward? they should cause the chain to move and the crank in the back to cause the wheel to spin, if this isnt happening, look at the chain and make sure its correctly on both sprockets, if the pedals still wont spin, they may be too tight on the crank.

Your pedal falling off is never a good thing, nor is the entire crank arm assembly.

For this one you are best taking it into your local bike shop and have them take a look at why both of these fell off. There are a number of reasons, from stripped thread to missing bolts and nuts to improper assembly. None of these are a good scenario with a childs bike, or any bike for that matter.

Alternative, and my personal suggestion - Take the bike back to where it was purchased and exchange for a new one. These parts should not fall off after years of riding let alone 2 days, and would constitute a warranty and safety issue.

I WOULD NOT RECOMMEND CONTINUING TO RIDE THIS BIKE, SINCE YOU DO NOT KNOW WHAT ELSE WAS IMPROPERLY ASSEMBLED.

I've had that happen with the exercise bikes that I have repaired My best suggestion is their any play after tightening the pedal if not remove the pedal an apply some blue loctite on the threads let it set up then put the pedal back. This should take care of it now if you want to get more radical then apply the red loctite, the only way to break the pedal loose is actually using a torch!!! good luck

You have to start pedaling to get it to start up, some times you have to pedal pretty fast to get it to start up

Change the battery. It is a 9v battery behind the small door on the back of the display panel.

Couple possibilites. If it is just a matter of your battery clips coming undone, tighten the with pair of pliers then reattach. If it cuts out, then reengages when you start pedaling, either your controler is shot, or you have a ground short on your wheel hub. How long does a charge hold, and how often does it cut out?