Frog Bikes is a UK-based company that designs and makes lightweight children's bikes. Like other bike brands (Islabike comes to mind) they were founded by parents looking for nicer bike options for their kids. Their goals are to make riding easy, comfortable and enjoyable for kids. The Frog 55 is a slightly larger 20" bike than the Frog 52, where the "52" and "55" correspond to the child's minimum inside leg measurement to ride that bike.
Slightly aggressive geometry
My kid currently rides a bike that is the same size (20" wheels). She said that the Frog 55 bike feels more stretched out than her other bike, but she didn't mind too much. On the specific bike that we had, the saddle could have been shifted about 3/4" to 1" forward to reduce the reach. The handlebars appear to be at the same height as those of the current bike.
Trigger shifters were nice (instead of twist-shift/gripshift)
The trigger shifters were a lot easier to use than the twist shifters that are more-common on kids bikes. I personally prefer trigger shifters for kids bikes, because many kids lack the grip strength to change gears with a twist-shift. Typically what happens when a kid needs to change gears (before they have the grip strength):
- Stop riding
- Put two hands on the shifter
- Twist really hard
- Start riding again (and have the chain jump)
Shifting is already a tough mental hurdle for kids to understand. Some say that grip shifters are more intuitive (Woom, for example, uses twist shifters instead of trigger shifters) - twist one way it gets easier, twist the other and it gets harder to pedal. But I've heard from too many parents (and seen firsthand) kids struggling with twist-shifters that are hard to twist.
Lightweight and feels sporty
I weight the bike, with fenders: The Frog 55 weighed 20.6lb. This is pretty nice and light, and lighter than my kid's other bike.
Many kids bikes are spec'd with Shimano Tourney or lower, so having an Altus rear derailleur on the Frog 55 was a nice touch. The brakes are by Tektro, and the axles are Quando quick release. It had fairly beefy Kenda tires with schraeder valves, and helpful green-colored spokes to make it easier to find the valve.
The fenders are definitely a nice touch for riding in the rain. The current fenders that we have are only 1/3 or so coverage, so these would work better.
The Frog 55 is nice.
All in all it was a nice bike. We didn't swap because we already have too many accessories attached to the kid's current bike.