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  1. frk1206

    Need ideas and framebuilders for v2 of my FS electric cargo scooter

    @999zip999 just one controlling both - the front engages a little later than the rear to prevent spin out.
  2. frk1206

    Need ideas and framebuilders for v2 of my FS electric cargo scooter

    Hey everyone this is something i've been working on a while now and its finally here and ready. This is a v1 or prototype of my urban electric cargo scooter designed to carry 2 kids and groceries up any hill. Its got dual grin all axle motors and a 1.8kwh custom battery pack by me. Currently...
  3. frk1206

    Which hydraulic brakes (w/switch) to fit my Grin all axle?

    I'm looking for a front hydraulic brake (with a switch) to fit my Grin all axle. The available clearance is only 18mm and since I'm unable to find dimensions online I'm wondering what other people have been using. I'm currently using a Sram Guide caliper that BARELY clears the hub but doesn't...
  4. frk1206

    Which end terminal battery solder is better?

    Yup thanks that was a dumb idea. I was trying to make it look pretty 🤣
  5. frk1206

    Which end terminal battery solder is better?

    Oh no you think it’s that bad? I thought some quick soldering not directly on the top of the battery was okay. I can take these cells out and replace with new ones so all is not lost.
  6. frk1206

    Which end terminal battery solder is better?

    I’m building my battery using the copper / nickel sandwich method. I did the negative side wire solder like this which is kinda yucky: Then I had a idea and did the positive side directly on copper. Way neater since I was able to do the solder prior to welding: should I redo the negative...
  7. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Though that’ll be awesome I just realized that something that just tells you to “inflate rear shock to 275psi and front to 200” is equally useful and possibly a good v1! Now if I can find a air shock that’ll take that much weight!
  8. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    So now you see where im going with this :) I'm a big suspension nerd and feel that if the suspension can be dialed in correctly in some smart way then it would be amazing thing to have on a cargo bike (safety and comfort wise). A cargo bike that you take alone as well because its so much fun to...
  9. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    ah interesting will that give you the force acting on the piston somehow? I didn't know that. do you know of a shock that'll take 400lbs? Mostly they seem designed for a 200lb rider + bike so around 250lbs or so. This number isn't published so hard to nail it down.
  10. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Interesting - I'm not a mechanical guy so can't speak for much about the design. Will ask the folks who are! Thanks for your input! Do you think the original design isn't going to be sturdy enough? Complex swing arm was a design choice - wanted to package the shock nicely inside the frame so...
  11. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Our thinking was that with a single big spring shock - we would have a lot more flexibility in choosing the right spring after the fact. You think an air shock would actually be better if we can get the load range right? I was under the impression that spring (downhill) shocks would be best to...
  12. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    It’s a work in progress didn’t mean it as a smart ass comment just that if you have access to resources why not do the hard work. How would you design the rear?
  13. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    This is what I’ve had for a long time and it’s not enough for me. If lightweight dirt bikes can do I don’t understand why cargo bikes cannot. The weight isn’t that variable since unless you are actually hauling very heavy cargo the target weight is mostly known (you and maybe a small child or...
  14. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Because I was able work with some experienced mechanical engineers :) A link type suspension will almost always be superior (even though require more work). Also it allows much neater inline packaging of the shock so can kids can sit peacefully and full side bags can be mounted.
  15. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    What do you ride and how did you build it l? Looking for tips on the rear suspension since it seems to be voodoo more than science. I’m with you on the 20mph - This bike isn’t designed to go much more than that but I definitely want a lot of torque to get to 20 quickly :)
  16. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Thanks for that tip! I'll look into those forks! Overkill is totally fine - Oakland roads are sometimes worse than the trails at JMP :o I used to be a mid drive guy (BBSHD) but the buttery smooth power delivery of the hub motors has me sold. The BBSHD was too much maintenance tbh - internal...
  17. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    SF Bay area roads can get as knarly as some trails, maybe even worse :P . Long travel + linkage in the rear means I can use a DH shock for much more weight since this bike is gonna be way heavier fully loaded than most DH bikes. On the front you are right probably a XC "ebike" shock which gives...
  18. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Full suspension. Still figuring out the exact components but most likely a Fox / rockshox downhill front fork.
  19. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    Yeah - I don't think I want to get into mass manufacturing or anything. Mostly just building one for myself and some low volume hand production for people that want them.
  20. frk1206

    My custom frame full suspension long tail dual hub cargo bike

    I couldn't find anything on the market that didn't suck so like a true engineer I decided to build my own. This is my long tail full suspension cargo bike cad model for a custom frame. This is going to be a 20" GMAC rear hub, 26" grin all axle front, 72V 2kwh custom battery. Why? because...
  21. frk1206

    Welding my cells - does this copper+nickel weld look good to you?

    I’m using a turnigy rapid 150c discharge lipo which a lot of folks like and is recommended by kweld for consistent welds. I did like a 100 practice tests on cells and on nickel/copper/nickel sandwiches to simulate a battery tab. They seem pretty good at 70J and pulling with pliers strips the...
  22. frk1206

    Welding my cells - does this copper+nickel weld look good to you?

    How do you guys test the strength of your welds and know if one is better than the other? Trying the sandwich method at 60J with kweld and they “look” good. Don’t come off by pulling either. So should I declare them good and move on?
  23. frk1206

    Increasing planetary gear reduction on my GMAC10T

    Hahah so I've since put my chain back on and I am the mid drive with a really high gear on the back. Pedaling my bicycle like a plebian. Just as god intended. :D :D
  24. frk1206

    Increasing planetary gear reduction on my GMAC10T

    Totally makes sense! My idea was to use the rear gmac for crawling and supplement it (with some custom throttle control) using a front hub that’s geared for speed. The idea being that that the front won’t be super useful for climbing since it gets unloaded - so the rear is the main powerhorse...
  25. frk1206

    Increasing planetary gear reduction on my GMAC10T

    Thanks guys - I already contacted grin but haven't heard back about this situation. They just said that their motor can never compete with a BBSHD in torque due to gearing - but maybe you can increase the gearing on the gmac? I usually would ride with my BBSHD in pretty high gear and was okay...
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