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  1. #1
    Senior Member G1nko's Avatar
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    Bionx - Removing the speed limit with BigXionFlasher

    This morning I reset my BionX system to remove the speed limit. With my current gearing, the maximum speed I can go is about 25mpg, but honestly, I wouldn't want to go much faster. At full-assist, the bike quickly gets up to speed and stays there with little effort. At lower assist levels, the bike acts just like it always does, with the assist matching my effort.

    Following the directions for the BigXionFlasher, I purchased a Crumb128 5.0 from chip45.com in Germany. I also purchased a male HR30-6J-6P hirose connector and a female HR30-6P-6S hirose connector from DigiKey. Everything showed up yesterday, so this morning I sat down and started soldering. I used an extra ethernet cable with the extra pair removed, since the Cat5e cable was 4-pair and I only needed 3-pair.

    The pins on the hirose connectors are really small; it was necessary to tin the wires on the cable long and then cut them to length, about 3mm. I also pre-tinned the pins on the connector. That made the actual connection of the cable to the connector relatively straightforward. This took about 90 minutes to prep everything and do the work.

    Following the directions, I checked the cable to make sure it worked. When it did, I cut it and soldered in the Crumb128 board according to the diagram on the BigXionFlasher website. This took about 30 minutes and was pretty straightforward. I only cut the cables to pins 2, 4, and 6, leaving pins 1, 3, and 5 connected. This made for less soldering since the odd number pins are pass through; they don't connect to the Crumb128.

    After that, flashing the board with the firmware was pretty easy. Windows 7 did not automatically install the driver for the CP2120 USB to UART Converter from Silicon Labs and install it manually. After that, though, everything went smooth. It took about 10 minutes to get the board connected to my PC and flashed. From there, I connected it to my BionX system. The cable from the console connects into one side of the Crumb128, the cable from the battery connects to the other. Everything loaded and a few seconds later I got a message saying my speed limit was off.

    The directions on BigXionFlasher seemed difficult to follow, but once I had all the parts in hand, it made a lot more sense. This was a pretty easy project, all in all. The worst parts were waiting for the Crumb128 from Germany (and even that didn't take too long) and soldering the pins on the hirose connectors.

    I don't plan on doing 25 very often, but there are some busy intersections on my commute where I have to take the center lane or the left lane. Drivers seem ignorant of my right to use the roads and can be unpleasant to deal with at times. It'll be nice being able to move through those intersections at a speed more closely matching traffic and then drop down to normal cruising speed.

    image.jpg image2.jpg
    '11 WorkCycles Secret Service | '98 Waterford 1250 | '87 Trek 330 | '75 Peugeot UO-8 | '48 Raleigh Dawn Tourist

  2. #2
    Senior Member
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    WOW, I wish someone could just leak the code, and I could just do it on the console by punching in some numbers... But good for you, I hope someday I can do that to my set up too, that sounds just like what I would concider a perfect set up...
    He uses statistics as a drunken man uses lamp-posts...for support rather than illumination. I do like my beer, so sometimes I do end up leaning on the lamp-post...

  3. #3
    Senior Member 15rms's Avatar
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    G! do you have the new 48 volt system?

  4. #4
    Senior Member G1nko's Avatar
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    Yes, it's the SL350 48v rear rack mount.

    I found an interesting downside to increased speed the other day. I was late for a dentist appointment and had to get 8 miles in <15 mins so I cranked it a little. I hit an expansion joint on a bridge really hard and dislodged the battery from the mount which knocked out power to the system. I couldn't unlock the battery from the rack because having it knocked out of the mounting rail put enough pressure on the locking mechanism to make it so I couldn't operate the lock.

    I had to put pressure down on one side of the battery to force it back over the mounting rail so I could release the lock (which was now broken), slide the battery out, and remount it. I didn't make it to the dentist.

    Watch out for the extra speed; it'll get you one way or another.
    '11 WorkCycles Secret Service | '98 Waterford 1250 | '87 Trek 330 | '75 Peugeot UO-8 | '48 Raleigh Dawn Tourist

  5. #5
    Senior Member
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    That is interesting... I was just thinking, Why didn't they put some rubber grommets in the mounting points onto the rear rack mount to the bike frame? It would be SOooo much less vibration to the battery, and the battery wouldn't take a beating at every pothole and crack in the road that the bike hits...?
    He uses statistics as a drunken man uses lamp-posts...for support rather than illumination. I do like my beer, so sometimes I do end up leaning on the lamp-post...

  6. #6
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    Regarding the battery coming loose, my system is six years old (I2C) and I've only had it come loose once, and that was a result of my ignorance in not properly locking it onto the dock the first week I had it. My mount is the downtube type. I've found them to be really secure when mounted on a rear rack instead of downtube. I suspect the engineering is a little more rugged. I mounted it on a rear rack because the forces on a downtube mounted battery worried me. A couple of screws on a water bottle mount don't seem very secure to me. I might have gone for the factory rackmount had it been available when I bought this system.

  7. #7
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    IMPORTANT - when ordering a Crumb128 5.0 please do not forget to specify a bootloader to be preinstalled. I made that mistake. I did not notice a check box for it on the chip45’s order page and I got a board that could not be flashed with their GUI. Fortunately, a local electronic shop has an inexpensive ISP adapter – usbtiny ($22 CND) which I used to install the BigXionFlasher software. Still, that simple mistake delayed me for few days for learning about MCU programming and tools used.
    One more thing I would also recommend. Instead of buying hirose connectors and wire just buy a BionX communication cable extension. They come in different lengths – from 30cm to more than a meter. On this way you will avoid soldering those tiny pins which is next to impossible with any standard soldering tool. The connector is easy to unscrew so you can see which coloured wires you will need to cut.
    Anyway – the final result is excellent. My good old 20” wheel 500W BionX system with the new 48V battery now goes over 50 km/h. The max speed when there is no load is just over 60 km/h, but with my weight and air resistance the real speed is around 50 on a level ground.

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