$950aud plus $140aud freight = $1090aud

Here's my slingshot at time of writing this page ( 230309) full fairing is not quite finished so no test runs done with full fairing as yet, but top speed
should be very high I would think ( depends on what voltage/amps  I land up using of course).

Considering the x5 motor has been used by some  tinkerers in ebikes at near or over 100km/hr I really think its best suited to special purpose projects.
Some other reasons I dont think its well suited to use in normal bicycles is its weight ( 12kg) and generally bicycles just aren't built to handle higher speeds
and would be extremely dangerous if used on road at high speeds, especially since cars would not be expecting a bike to come towards so quickly, drivers are likely to pull out in front of a bike, also the power levels the motor can handle are way above regulations for ebikes.
Although the motor is successfully being used by alot of people in normal bicycles ( generally mountain bike style bikes) my view is you can use much lighter motors
to get same/similar results if using 48volt and 20 to 30amps or less. If your looking for a motor that can handle alot of volts and amps then this motor is very suitable. Its appears that the motor can be run at around 9kwatt peak for short periods, for continuous useage a much lower power level is required ( probably somewhere between 2.5 to 3 kwatt continuous).  Being a brushless gearless motor it runs at high efficiency at higher speeds, on hills it can lack power unless quite alot of amps are put through it. For projects where speed is the goal and major hills are not involved I think this motor is a very  affordable alternative to the more expensive motors being used in solar race cars ( eg ngm, csiro etc).

I keep stock of x5 motors in Australia but can also have them sent out from china to other countries.

The model which I tend to keep in stock is the X5303 which has plenty of top speed and torque for most situations . I have tested the X5304 model but at 85volts and 35amps the top speed was just under 50km/hr in a mountain bike. There are quite a number of different rpm x5 motors. The X5303 has a higher top speed ( on 48volt 35amp you can get around 50km/hr ).  So I'll go with the X5303 model in future unless someone has a specific need for a different rpm version I can order from crystalyte.

The X5 is a big , heavy and powerful motor weighing 12kg and a diameter of 24cm.
Why I dont think its  suitable for normal bike use but rather in 3 wheel or higher speed projects ( just my personal view):
1. lets say your running the x5 on 48volts and 20amps. You will be able to achieve equivalent top speeds/torque with a smaller/lighter  motor and use less amps to achieve the same.
2. x5 at no load full rpm on 86volts will draw 8amps. So you need to be able to supply quite alot of amps just to overcome cogging effects.
3. The motor is ideal though for higher speed 3 or 4 wheeler projects. The motor can handle high voltages and alot of amps without overheating. Max temp 160degC.
4. In an ebike the motor is 12kg which is alot of weight to carry around, once you add battery weight your looking at quite a heavy ebike.
5. Normal bikes are not designed for higher speed use and cars are not expecting an ebike to be going so fast, so its basically an accident waiting to happen.
6. Running the motor on higher volts/amps its going to be over ebike power limits in most countries and hence illegal for one road use.
7. As the motor does require quite alot of amps to get the most out of it, that means that quite large battery packs are required to get a decent range, thats another
issue for use on bicycles.

Picture below shows x5303 motor on right compared to a standard size 408 hub motor.

Whats in the kit:

1. X5303 motor ( other versions of X5 can be ordered but not generally kept in stock).
Latest model supplied which requires no dishing or rim for rim to be properly centred in bike frame.
It will fit into a starndard 135mm rear dropout width

If I supply a motor within Australia from stock I keep here, its preferable that the customer spoke the motor into their own rim, as its quite difficult to send
large boxes within Australia. If a kit is sent from china its actually no problem if the motor is spoked into rim already as the freight companies are ok with that size of
box ( its quite a paradox that its easier/cheaper to send a large box from china to australia, than to send within Australia!)
So basically if you want already spoked into a rim I need to send from China, if you want to save on freight costs then I can send not spoked into a rim from stock held within Australia. Spokes are of course supplied to fit the particular rim size. I get spokes of 3.2mm dia made to use with these motors to make for a very strong wheel.
Rim used is normally a wide dual wall aluminium rim. I'm using very wide 3.7cm diameter spokes on these motors to avoid spoke breakages
 ( tyre and tube shown in picture below not included).  A one cross spoking pattern is used. Picture below left shows x5303 installed in a 26" rim.

Rims and Spokes:

There is another option on rims if more robust rims/tyres are needed for heavier vehicles if bicycle type rims do not suit ( the alternative rims are inbetween bicycle type and motorbike type rims, they are steel and capable of carrying large loads), there is also some choice in tyres to fit these heavy duty rims. Standard bike tyres wont fit these heavy duty steel rims.

Below a pic comparing left to right: racing bike rim ( less than 2cm wide, middle widest dual wall aluminium rim I could source, right: heavy duty steel rim). The middle rim ( 3.7cm wide ) is the normal rim I supply x5 motor spoked into.

Below closeup comparing wide dual wall aluminium rim to the heavy duty steel rim: tyres used on the heavy duty rims are not bicycle type tyres, they are inbetween a bicycle and a motorbike tyre. So a particular type of tyre is required to go onto these rims. They are very common in china being used in electric trikes that transport heavy loads, so not very expensive. The tyres used on the heavy duty rims you can get them off using tyre levers, much easier than motorbike tyres, but harder than bicycle tyres. One issue is the x5 motor has 36 holes for spokes, these heavy duty rims have 40 holes, so it would be necessary to miss 4 spoke holes on the steel rims. Even so the load carrying capability would be much higher than a wide aluminium dual wall rim.

The other nice thing about the steel rims is the tyres they use are quite wear resistant and designed to take large loads, load ratings depends on the tyres but 250 to 300kg is the norm. There are a few choices on the tyre that can be used I'll put up some pics as times permits on those. Interestingly there is one particular tyre that fits these rims which is rated up to 600kpa .I shall put more info up on the tyres when i take some pics of them.

Video of testing using bike above:
 

Below no load rpm test ( thanks wayne in south africa for testing): x5353 on 74volts using infineon chip controller 12 mosfet version

Independent torque graph (below)  I had done on  an x5304 motor running on 36volts (sorry haven't organises any tests on higher voltages or on the x5303 maybe at some time in future will be able to do that as time permits ).
Results from Torque Testing Machine: