Motor challenges:
It turns out to be very difficult. First off most fat bikes just use the Bafang and similar 500-750W hub motors which are mass produced these days. We tried all of them and the performance just cannot be called "Hyper" anything.
The other way is to go with a mid drive, but the available strap on 1,000W mid drives out there are not torque sensing. They are also somewhat clunky requiring many gear changes as you move faster or need more torque.
Now some 1,000W mid drives with torque sensors are slowly coming to the market. But they still suffer from the need for constant gear changes for electric motors which technically don't really need to change gears.
Only the human needs to change gears as humans have insanely narrow power bands relative to electric motors. But since the human and motor's power are forced through the same transmission. The electric drive system is compromised and this becomes apparent when you try the really high powered mid drives. But it does work well for lower powered system.
Also you really need exotic derailleurs to cope with the power being sent through the transmission. Mid-drives are already technically more complex and as a result more expense piled on more expense.
So we went with MAC Motor at the moment they completed the Fat spec motor. They usually make very high powered motors for DIY bikes with the "need for speed." This 1,000W motor is incredible, but has never been integrated into a torque sensing production e-bike. It also has some quirky features that makes it difficult to integrate. Like the strange position of the hall sensors and lack of a speed sensor. The motor is relatively light and I guess there are some compromises due to weight and the need to fit the motor into standard 135mm rear dropouts.
Our controller supplier is quite good. They make all of Bafang's mid-drive controllers from the smallest to the largest. The have become masters at translating how you want the torque sensor to feel into code that's programmed onto the controller.
They tried in the past to tune the MAC motor and just gave up. We begged them to try again and it took many months and many failed or half working systems before we got the thing to work. We had to bring these two very different suppliers together to focus on jumping this hurdle.
Sometimes the MAC engineers went to the controller supplier to help work out issues. Many times we went there and spent days at a time at great annoyance to everyone considering the relatively tiny number of units of this project.
We also had to make our own wire harness because the motors wires are so big. Also the lack of speed sensor means we had to make provisions for an external speed sensor which is kind of clumsy since like every other hub motor has a speed sensor.
We wanted an advanced display with a silly number of features. Some did not appear to make sense, like deactivating the torque sensor, but they made each one of them.
It took way longer than expected, but amazingly at the end of the day it works! And its a beast and there is nothing like it on the market.
We feel that this is the maximum speed that this work can be accomplished in this industry for a production product. We know many full bike manufacturers are trying to pull off the holy grail - the 1,000W, high speed, geared hub, torque sensing e-bike.
There are many challenges and its very easy to walk into the ring and get punched out right away. And this is just on the motor side.
Battery issues:
Another huge challenge is the battery. To power such a motor you need a huge battery, there is no way around this at the moment until scientist invent a better battery. For now we have to work with the materials that are available or the bike will never come out.
A huge battery takes up lots of space on a bicycle frame. We wanted the battery to look as slick as possible, to be backwards and forwards compatible with every bike we made and will make, be lockable/removable and sit integrated low on the downtube. The pack cannot interfere with the optimum frame geometry for pedal powered bikes as we want it to feel like a real bike.
The capacity needs to be around 1KWh with readily available cells. Such a battery just does not exist on the market.
Basically most everyone making factory-assembled e-bikes in China buy the battery case and tube and welds it to the frame and boom, we are in the e-bike business. The pack sits either integrated, bottle style, or rear rack style. Some are making triangle type, but they are normally not removable which makes it difficult for us to service and was ruled out.
So all the e-bike start looking the same. This happens because it is expensive and time consuming to make a battery case. There are companies that specialize in case making and you must only buy it from them.
But what if we want more battery capacity than already exists? You can use multiple batteries which we ruled out as being too goofy of a solution... Or you have to make it yourself and this is exactly what we did to reach our performance targets.
This route is very much going against the grain, difficult and full of challenges. We had to figure out and solve all of these challenges but the result is incredible. It has 1kWh of energy, nearly double what's found on the average e-bike. The larger case has room for a massive 45A BMS, nearly double that of the average e-bike battery. It can super charge at 10A, that is 4 to 5x faster than most e-bikes are doing. It works on just about every "Current" series e-bike we have ever made. And sets the platform for future expandability.
Rather than make the case longer which is what everyone else does, we made it slightly wider and shorter. This way we could fit the huge 12 Transistor controller into the frame of the bike so it does not need to be unsightly or strapped to some part of the frame like a wart.
This downtube style of case usually have the cells stacked like roman candles. This configuration is a massive headache for battery suppliers and they really hate to do it. We literally turned things on it's head and put the cells sideways in a grid so they can be automatically welded and easily fit into the case. It sticks out to the side a little bit (which we will fix later) but the compromise is well worth the performance.
We developed this somewhat in the open and already found some supplier presented the 3D printed clone at the trade shows. It really does not matter, because in China, everything is a copy and if you made something that is not copied, it just means that there is no money to be made from that product at the moment.
GPS integration:
The battery packs now all have GPS integration capability. This is real tracking, sending actual coordinates data over the GSM network with its own sim card. This is insanely awesome as you can get a notification when someone so much as just touches your bike. If the crook rides off with it, they WILL be tracked down.
Brakes:
Some people noticed the brakes. The brakes are mechanical and that is due to lead time. Hydraulic disc brakes are harder to get hold of and dramatically increases the time it takes for the bikes to get to the market and most of all the good ones are made in Taiwan and have to be imported to get them to China. This double import is expensive and time consuming. It will improve later, but this is the current situation.
On the CrossCurrent we used the HD-715 hydraulic disc brakes. Those are like some of the highest performance brakes available. We put them on our mid-grade bikes and this reduced the speed at which we could manufacture the bikes. Braking is very important but unfortunately sits way down on the list of things people find valuable. Now we use decent mechanical disc brakes and give the option to upgrade the brakes. |
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