Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.
I really wanted to love this bike, I've only had it a few days, and it's probably too soon for a review, but I can see some issues with the bike. I'll start with the good, it was here 2 days after I ordered it which was amazingly fast shipping, the bike was easy to assemble, very sturdy and high quality looking and feeling, and even came with a nice tool set for assembly and a bell and water bottle, pretty good saddle, and I was very happy with the price, if it performs as I hope it will. Now the bad, as soon as I get a quarter mile from the house my battery indicator light goes from green to yellow, that is way too soon for the battery on a bike with this alleged range to be at "half life?". I have read in other reviews many have the same issue and say that it is just "inaccurate " and to "not pay attention to that" but it is disconcerting to me. Also the bike does not have the power I was expecting, it is truly a "peddle assist" bike, and not a throttler, the bike basically wants you to peddle and works best as you peddle, in fact the motor actually cuts on and off based on you peddling, in addition to cutting on with throttle, don't get me wrong it will power through on throttle alone on a flat surface pretty well, but if you expect not to do much peddling at all, this is not the bike for you. The fit of the bike isn't great for me, I am 6'2 and the fit for me is a bit awkward, ie: the bike is a bit small for me, anyone my height or taller may want to look at other options, and I can't raise the handle bars at all I don't think, although I believe you can change the angle of them. I've only taken it for 3 short rides as of yet and I was reasonably satisfied with the bikes response and power for my needs on these short trips, but I will have to take a few longer rides before I can give a more complete opinion. The bike is an eye catcher and I see people staring at it everywhere which is cool, I will update as long as I continue to own the bike, but I'm still a bit on the fence about it.
The new Stumpjumper is the ultimate trail bike. Seriously, the damn thing rides like it’s on rails. It’s the most versatile trail bike we’ve ever made. And yeah, we’re stoked about that, but we’re even more excited about how well it’s tuned to you. We’ve said goodbye to proprietary bullshit, focused on your needs, and made, what we feel, is the new benchmark in trail bikes.
The need to develop a high-performance e mountain bike provoked the launch of the ATOM X project over three years ago. A team of experts was put together from the fields of MTB geometry, suspension and performance, advanced motor, battery and IT technologies. That is how the innovative and patented “X System” came about, which represented an integration that was both ergonomic and different. It was developed until it became the best eMTB with the best of both worlds: high performance and the most advanced electric technology. See the ATOM X e mountain bikes...
E-bikes use rechargeable batteries and the lighter ones can travel up to 25 to 32 km/h (16 to 20 mph), depending on local laws, while the more high-powered varieties can often do in excess of 45 km/h (28 mph). In some markets, such as Germany as of 2013, they are gaining in popularity and taking some market share away from conventional bicycles, while in others, such as China as of 2010, they are replacing fossil fuel-powered mopeds and small motorcycles.