LocationWoods Hole, Massachusetts United States map
Vehicle2010 Mongoose Crossway 450
aluminum hybrid; mechanical-actuated f/r discs + front shock standard.
MotorGolden Motors Magic Pie 3 Brushless DC
1kW@48V hall-effect-sensor hub motor.

actual axle spacing is 133.5mm - washers or spacers are mandatory on each side, inside and out (and not just for spacing, the axle will eat the dropouts otherwise) - I wish they threw in a handful of extra washers or at least let you buy a bag of them separately.
Drivetraindirect-drive from hub motor.

otherwise: standard chain, originally 8sp, now with 7sp hollow-back hyperglide clone. (marked "Shimano HH" - H must be one better than G, right?!)

7 v. 8 gear spacing and widths not exactly the same, but seems close enough (see specs WebPage )
ControllerGolden Motors mp3 built-in
hub-internal controller. 1kW@48V, regen, programmable.
Batteries1 48V10Ah LiFePO4, 48.00 Volt, Lithium Iron Phosphate
alloy shell rackmount, built-in BMS.

brackets for attaching quick-remove shield to rack are not well thought out, had to source longer bolts. or maybe just order one of their special double-deck racks next time.

IEC C15 connector on the shell for output is not the smartest thing ever. something you would never confuse with 120VAC might be better, not to mention something gasproof.

ordered some right-angle and down-angle C14 rewireable connectors, seems more sensible than the straight-out C14 it came with.

generic C14/C15 connectors seem to be rated at 10A, so there's another design flaw - system is fused/rated at 25A minimum.

also picked up some xt60s to replace harness bullet connectors.

or maybe just replace the entire shell connector with xt60 (is there a bulkhead version?) or anderson/sb50 connector...
System Voltage48 Volts
Charger EMC 120W
48V@2A, charges at 57V. this is basically the least-expensive charger, comes included with the battery pack. new to me, complete charge time is yet unknown.
DC/DC Converter random HK 48V-to-12V
just for horn and lights...
Instrumentationmaybe cycle analyst, or more likely cheap 48V LED with a bad power meter, or one of those RC plane meters
Top Speed30 MPH (48 KPH)
it kinda really zips
Accelerationstandard by 5
Range25 Miles (40 Kilometers)
regen helps only a little
Watt Hours/Mileneeds calculation!
EV Miles
Current:15 Miles (24 Kilometers)
Seating Capacity1 adult
Curb Weight66 Pounds (29 Kilograms)
needs measurement. orig bike is about ?26lb; +26lb battery +14lb mp3hub
Conversion Timelazy-ass took 2 weeks to complete. actual total labor time: 2 days.
Conversion Costand counting...
Additional Features48V low-tone forklift horn - TOO LOUD! but at 12V it sounds ok, will have to add a converter.
I want to lie shipwrecked and comatose, drinking fresh mango juice

10/3 got a pack of xt60s today better solder those guys on....

(why "urban defense"?! I have no better name for this unholy thing, and Mongoose, in some fit of random questionable wisdom chose to, from the factory, inscribe this very intriguing epithet on both seatstays - go fig.)


frame is 135mm rear, but aluminum. maybe not the best choice - serious thinking involved regarding spacing, to get good clearance on both drive side and disc side and yet not require spreading.

hollow-back freewheel is very important for this - flat-back types will require the included spacer, which then makes the dropout spacing very tricky.

even if you did not need proper spacing on the off-drive side for the disc, there is still probably no way to get proper spacing on the drive side for an 8sp (except maybe with a steel frame)

disc needs to be spaced outwards with washers inside, and regular disc bolts are too long (fan housing where the disc bolts on is very close to hub body) so need cut down bolts or else add washers on the outside of the disc as well.

the hub came prebuilt on a heavy dual-wall rim. 20mm tape worked fine, 17 or even 22mm probably also ok. put a 700x40 tire on with no problem. the rim is surprisingly true but has a nasty flat spot where it must have been dropped in shipping, and dish is a bit off, and 3 spokes all next to each other are completely loose, and can't be tightened anymore. wheel will have to be rebuilt, not just trued or dished - this is really disappointing.

also have a pair of torque arms (e.g. WebPage ), because from everything I've read, the axle will *still* want to eat the dropouts. apparently goldenmotor had the thought to make the axle much longer in newer models, so there's no problem getting these as well as the tabbed spacers on and still have plenty of threads for the axle nuts. it's very crowded though (esp on drive side obviously) so for now the arms ended up strapped to the rack support stays.

did not come with all necessary wiring, needed to add a pair of 14/16ga wires and 14/16ga crimp bullets (1m 1f), to wire the included IEC C14 so it could connect to the m/f bullets on the motor's power input wires. some heatshrink or other weatherproofing will be nice here too.


finally more work done - had to cut away about 1" square from the upper lip of the rear rack, so that the battery cable would fit. also, the panniers probably won't fit anymore given the way the battery quick-mount plate sites - this is going to need a solution.

crimped on bullet connectors, although I may just end up wiring a right-angle C14 directly to the controller harness, when it arrives - if it's possible to make it weatherproof enough.

controls are now mounted right hand side, as follows (l to r)
- chain shifter
- horn/cruise
- regen brake lever
- throttle/LED

left hand side brake I left alone, one side should be enough for regen.

there did not seem to be any specific/standard way to mount the controls, goldenmotor was more "put them on however is most comfortable for you", which is nice. although if space gets tight, it makes the most sense to have the brake lever left of the throttle.


first test drive today, rode the bike to work and behaved admirably (other than ugly flat spot in the rim and subsequent bumping feeling) - no problems reported.

on the ride home, lost all power, unsure why - checked mechanical connections for battery power but all seemed fine. two other friends tested after that, same sort of experience - worked fine mostly but lost power temporarily at some points. probably just need to make better connections on battery cables...

code by jerry