> Guessing it gets bit sketchy fighting gravity.

The big risk is going too fast: because the wheels use balance (forwards/backwards) to know whether to accelerate or slow down, if the wheel goes beyond a certain speed it tends to behave somewhat oddly, some models will lock and stop, others will "freewheel", either way the user will likely end up eating pavement.

IIRC the latter is the behaviour of the interviewee's rockwheel, it starts beeping (in several increments) when closing in to maximum speed, then the systems just shut down and you get a completely unmanaged unicycle (without electronic stabilisation). Other wheels will try to forcibly rebalance the user, but again it's fairly easy to defeat, not much the wheel can do if you just lean forward despite its best effort… and you eat pavement again.

Aside from that, acquaintances who've tried/used them tell me they're fairly fast to learn and very enjoyable and convenient.

But can't you go down a hill slowly by just not leaning as far forward? Trivially, these allow you to remain stopped on a slope, right?

> But can't you go down a hill slowly by just not leaning as far forward?

Sure. But there is a higher risk on losing control on downhills, and if you do the only brake is to bail.

I'm fairly sure these devices (along with Segways) are illegal to use on the road in the UK[1] (I believe you could use it if you registered it as a vehicle, but then you need tax, insurance and an MOT if they're over 3 years old).[2] I guess now they're so cheap people are willing to take that risk (or just aren't aware of the legal situation).

The government apparently pledged to make Segways (and then presumably all these self-balancing 2 wheel electric scooters) legal but never actually did.

[1]: http://www.legalisesegways.co.uk/ [2]: https://www.gov.uk/electric-bike-rules

We have some strange and outdated laws. The electric wheelchair laws are also interesting:

https://www.gov.uk/mobility-scooters-and-powered-wheelchairs...

In particular as you need to register them which seems pointless and antiquated.

Someone in London too. Not as stable, though. He hopped on it and promptly fell over ;)

I've seen a lot around Oxford Circus, I'm gonna guess tourists or hipsters ;)

there's a guy in Highgate that cruises around on one of these with a mohawk and a duster billowing in the wind. He rides his in the road, a good thing too as I've seen him go at around 20mph.

I used to ride down the steapest streets in twin peaks, SF - a little harder than normal to keep balance but it slows for you. The tricky part was getting back up, it drains the battery rapidly so easy to run out of juice and the carrying these by hand is a massive workout. I have the solowheel, I think airwheel is a knockoff?