Count me at another person who is watching this. I really want to build up a mid drive BMX bike as a pit bike. I'm pretty sure I would be fine with 1000W for cruising around the pits.
Count me at another person who is watching this. I really want to build up a mid drive BMX bike as a pit bike. I'm pretty sure I would be fine with 1000W for cruising around the pits.
In reply to OHSCrifle :
It should, it ate my pants yesterday.
In reply to mazdeuce - Seth :
That would make a nice little pit bike!
Batteries! These are cheap ish lipo from hobby king. 16ah worth. It's making a 14s pack.
Made the umbilical from backpack to bike. Came out nice I think!
Got a 6 pin waterproof connector to run the Halls through.
Wiring the motor side.
Braided sheath over everything coming up from the frame side.
Feeding all the wiring into the saddle bag that will house the controller.
Bag in place
On the test ride!
Man Java, I REALLY want to do something like this. I've heard of the infinite sphere forums- are there any other sources so I could do something like this too? And is it better to go with the hub motors or separate chain-driven ones?
In reply to GIRTHQUAKE :
Endless sphere is the biggest forum AFAIK.
Hub motors are simpler install, much simpler. But add a lot of weight to the wheel. If your just cruising on pavement, should be fine, not quite as efficient though. Hub motors can go 3kw plus too. They beat spokes and rims up if your going on trails
Good to know! Thanks!
In reply to GIRTHQUAKE :
I'll put together a list of parts Monday 
Would you mind sharing expenses with us?
In reply to DrBoost :
Will do! I will put together a parts and prices list!
OK Parts and prices list!
3000w Kit Sick Bike Partsor Luna Cycle I used SBP as they had it in stock and are local ish to me. $350
Thumb Throttle SBP $25 (not needed, the kit comes with either thumb or half twist, but the volt gauge is only good to 48v, I wanted one that would read correctly for my 52v pack)
Batteries will get a bit more complicated, it will vary depending on how much range and voltage you want. More voltage=more speed, more amperage=more torque. The kit is advertised as 3000w, but that is at 72v. I went with a 14s pack, which is 52v nominal, and 16ah. Speedy riding is supposed to be roughly 1ah per mile. The batteries can be had anywhere between 3ah and 20ah, this will drive price accordingly. You can also make a 12s pack or a 18s if desired (simply use different number of cell count batteries).
Second note on batteries, I am using Lithium Polymer, they are very energy dense, but also want to be treated with some respect, abuse them and they can burst into a lovely chemical fire.... You will need a charger designed for them, it should be able to balance charge, you want the cells all within .05volts of each other in an ideal world. High internal resistance or cells that are at different voltages can cause the packs to melt themselves down. "puffing" is generally the first sign of a pack going south, a cell will get hot, or may not, but will start to expand, If it puffs don't keep using it (IMO!).
For a 16AH 14s pack I used
Two 4s 16000mah and One 6s Wired in series. $242.21
Charger again is up to you, make sure it can charge 6s if your using a 6s pack, some cheaper ones stop at 4s. I would suggest 10amps charge rate if you can. It takes awhile with a big pack. Most will also need a 12V power supply. (I had a charger from my RC stuff already)
Misc parts:
Lipo cell monitor. This is kinda the bare minimum system, volt gauge and a cell checker (you dont need the volt gauge...) The cell monitors have a buzzer and can be set of a cutoff voltage. Lipo packs DO NOT want to get below 3v per cell, EVER. These will warn you, I set mine to 3.4v usually. Amazon $7
Battery connectors, XT90 (i got anti spark, but you don't need, it, its just nice. The spark will erode the connectors over time.) Amazon XT90$12.99 You need at least three males, the batteries get wired in series.
So that is bare minimum, assuming your OK with clunky Chinese electrical connections, supply your own wire etc.
Total is $621.19 Not including the charger
Now a few more things I did:
6mm Bullet connectors for the phase wires, gets rid of the huge plastic things. $11.99 Amazon I got 20 pairs.... If you have a local hobby shop you could probably buy the three needed a lot cheaper.
10 gauge silicone wire. The batteries are good for 160amp currents, big wire is good. $16.59 Amazon 20'
Crank puller and BB tools, you will need them.... $8 Amazon
Connector for the hall wires (I probably would just solder them if I was doing it again, how often will I remove the motor?) $10.89 Amazon
Braided sleeve, because its awesome stuff.... NOTE the XT90 connectors do not fit through it (I found out the hard way) $15 Amazon
Saddle bag for hiding the controller and connections. Could just be zip tied. $12 Amazon
So add another $75 for all the little goddies.
So lets say $696
Charger $53 Hobby King add car battery or 12V power supply (old computer PSU or Amazon has lots)
So here is my battery charging setup.... V1.0
Now I say V1.0 because apparently that power supply was not happy running the charger with bigger packs, its always been fine for my smaller RC packs, but I let eh magic smoke out....
NFG
Intermediary, v2.0. Old computer power supply, you need to jumper between the green and any black wire to get them to turn on, but then black to yellow is 12V. was not getting the wattage needed for 10 amp charging still.
So v3.0 is a real power supply....
36.3 mph with a full pack. Sorry for the shaky video, handle bar mount..... Its not nearly as noisy as it makes it sound, maybe the camera being mounted to the frame?
This is fun! Just did 5.2 miles.
Cool build!
Very cool. Take it easy on that Intense. Despite their high price (that was a $1700 frame when it was new - yes, just the frame) and they are not famous for their durability. I currently have four modern Intense carbon frames plus one aluminum. If in good condition, that XTR rear derailleur actually has some value on the vintage mtn bike market.
Very cool build. I have always wanted to make something with an electric motor. It is on my list of projects that I really want to do but probably don't need.
Keep an eye on the brakes. I am not sure they were not designed to provide braking power at those speed and will probably wear quickly. It is always a good idea to do a safety check.
Ian F said:Very cool. Take it easy on that Intense. Despite their high price (that was a $1700 frame when it was new - yes, just the frame) and they are not famous for their durability. I currently have four modern Intense carbon frames plus one aluminum. If in good condition, that XTR rear derailleur actually has some value on the vintage mtn bike market.
Yeah they are not cheap frames, this one looks in very good condition and the PO was a bike guy so it was well cared for. The XTR stuff is all perfect :) Shocks still need rebulds, but frame is good. Wheels are not going to last I fear though, the rear hub had some slop in it already.
tedroach said:Very cool build. I have always wanted to make something with an electric motor. It is on my list of projects that I really want to do but probably don't need.
Keep an eye on the brakes. I am not sure they were not designed to provide braking power at those speed and will probably wear quickly. It is always a good idea to do a safety check.
Its a TON of fun, seriously. I agree on the brakes at full tilt boogie they are really maxed hauling down to a stop. But they are good quality and hydro, so I hope they last a bit. Pads may go quick.....
If you need pads, let me know - I have a ton left over from when I raced DH with those brakes (Hayes). EBC "Green-Stuff", IIRC.
FWIW - the brakes use Dot 4 fluid and are typically bled using a syringe from the caliper with a capture bottle at the lever.
In reply to Ian F :
Oh very cool! I'll see how they are holding up. Id be happy to liberate your stash of pads.
Yeah I have run the Hayes hyrdos for years, I have all the bleeding stuff somehwere....
It's sad how Hayes brakes were the E36 M3 back in the day and now they're crap. My team has a deal with Hayes group and I tried like hell to run them on my bikes, but finally had to give in and switch to Shimano XT for trail/enduro and Saints for DH... I've been pestering our rep for a "proper" gravity brake for years. The ultimate indignity was last year when the World Cup DH team sponsored by Hayes Group was running Magura brakes.
I kept my old-school Hayes stuff as I still have a vintage DH bike with them, but I'm planning sell off all of my old stuff in the coming months.
In reply to Ian F :
Huh thats no good to hear, I have been out of the mtn bike world for a decade (or more) these were basically new on my old cruiser bike, I just swapped them over. Whats so bad with Hayes these days?
I understand the downsides of hard to repair, but I got out of the bike world when cable disks were just coming out and SUCKED.
From a technical aspect, I don't really know - they're just really down on stopping power compared to newer brakes. I rode my enduro bike for the first time in awhile and at the first corner nearly pooped myself, "Oh crap! No brakes! No brakes! Tom! MOOOVE!!!" The first half of the ride was kinda scary until I readjusted to the increased effort and distances required compared to the XT's on my trail bike.
Cable brakes have gotten better, but still kinda suck. TRP makes one that works reasonably well, but it has a little hydro mechanism in the caliper and the cable is essentially pulling on a integrated master cylinder that moves the pad piston(s). It's mainly marketed towards the gravel/touring bike crowd with drop-bars. It's the only cable brake I've tried that has a nice, solid lever feel at the bars.
In reply to Ian F :
Interesting, I wonder if its a lever geometry or master sizing issue. (or moving to mineral oil?)Who knows.... Mine work well, just need to remember moving at 30+ takes some time to haul down.
Switch to something like Shimano Saints or their less expensive, but still very good Zee brakes with 4-piston calipers and you'll have no concerns about hauling down from 30+ MPH.
My more recent Hayes still use Dot 4, although due to rider complaints some of their models are running mineral oil.
In reply to Ian F :
Cool, I may look for some Saints used, if they are really that much better, these can go back on my cruiser.
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