Scooters and ABS brakes
ABS stands for "Antilock Braking Sytem". ABS brakes are now pretty standard on cars. They work by using an electronic sensor on each wheel. If the sensor detects that the car is moving, but the wheel has locked up and is skidding, the brake pressure on that wheel is electronically modulated so that the wheel isn't locked but is providing enough braking power to be just on the verge of locking up. That gives you the maximum possible stopping power.
99% of the time, ABS brakes are much safer than non_ABS brakes, the only exception being when stopping in something loose like sand or gravel, where a locked wheel can "dig into" the ground better and slow a vehicle down faster. However on the road, ABS will outperform non-ABS for almost all drivers. So if ABS is so great, and if locking up the front wheel on a scooter usually results in loss of control, wouldn't it be nice if you could get a scooter with ABS brakes, or at least an ABS front brake? Well, you can - if you pay for it. For example the Honda Reflex sport is available in two models, without ABS for $5550 and with ABS for $6050. The Honda Silver wing without ABS is $8100, with ABS it's $8600. So at least on those Honda scooters, ABS costs you about $500.
"BUT", you may say, "I've seen a bunch of Chinese scooters with ABS brakes and the price for the whole scooter is only $1200. Am I getting a bargain?" The short answer is no, you're not getting a bargain and you're not even getting ABS brakes.
Well it says "ABS", but is it really?
Well, I suppose you are getting a sort of ABS braking system, but what it is (if it's more than just a decal on the scooter) is a pressure limiting valve which limits just how hard the brakes can be applied. Above a certain pressure in the hydraulic brake line a pressure relief valve may open. Obviously if you can't apply the brakes really, really, really hard, you probably won't lock the wheel, so in a sense you have an "anti-lock" system, but it's not the ABS system that you might expect.
Is it dangerous? Well, maybe. If you want to apply the brakes hard and the "ABS" system decides it wants to dump 50% of the stopping power just to make sure you don't lock the front wheel, then there could obviously be problems. My own scooter has such "ABS" brakes (at least on the front disk) and so far I'm quite happy with the braking power. I've never felt any sort of modulation of the brakes and the harder I brake, the faster I stop, so either the "ABS" isn't working or it's set to some high value of braking power that I have not yet reached. However I have not tried an emergency stop from 60 mph because if the brakes do lock up at that sort of speed, the "test" may quickly become an accident!
True ABS braking works well on very slippery surfaces such as wet roads, snow and ice. A pressure limited "ABS" system won't do that, so even if the chinese ABS system did any good under hard braking on dry roads, it would still fail miserably in the rain and snow, which is exactly when you most need it. It wouldn't be any worse than regular "non-ABS" brakes in the rain, snow and ice, it just wouldn't be any better or safer. I have tried hard braking at safe low speed on a wet surface with my scooter with an "ABS" frint disk, and just as you'd expect from a "pseudo-ABS" system, the wheel locks and the scooter skids. Pressure limiting ABS does absolutely nothing to help prevent skids on wet or slippery roads.
The point to be made here is that NO Chinese scooter has true ABS brakes such as are found on cars. Any claims of ABS braking are at best misleading and at worst illegal. The only scooters with true ABS brakes are a few of the "maxi-scooters" and it will typically add $500 or so to the scooter price. The "ABS" braking label on Chinese scooters is very misleading. It's been suggested that APS actually stands for "AntiLock Braking Sticker". Opinions differ on whether it's actually dangerous, but there are probably tens, even hundreds of thousands of such scooters out there and so far I haven't heard of any product recalls mandated by the DOT or other regulatory or government actions due to safety concerns, so I'd have to conclude at this point that the "ABS" system on chinese scooters doesn't do a lot of harm.
BTW Chinese scooter rear brakes aren't even claimed to be ABS. Normally they are drum brakes and my experience is that even if you apply all the braking power you can, you can't lock them up on a dry road because they aren't that powerful! At least 70% of the stopping power of any scooter or motorcycle is done by the front brake just because of the mechanics of weight transfer under braking.