Need advice for planning my build

[Obelous]

I am looking for a 3kw conversion for commuting that can do 40mph reliably for about £1300
Currently considering:
LG 72v 30ah 80A BMS from https://risunmotor.com/ (technically Chinese but seems legit) £550
Crystalyte 3540 from Crystalyte Europe (with grin torque arm) ~£400 + ~£170
Sabvoton 7280 from MQCON-e bike controller supplier ~£150

~currency converted

Grin has 2 versions of the v7 regen torque arm a 12mm and 14mm I'm not sure which one the crystalyte motor needs.

Crystalyte says their motors are rated for 50A so I'm going to try some different settings in the controller to see what is enough for me and if the motor can't handle it I'll buy statorade and hubsinks.

My frame is aluminium but my drive side derailleur hanger dropout is silver coloured so it might be steel? Seen a few horror stories about high power motors on aluminium frames so hopefully the grin torque arm should be able to handle it, looking to add a regen thumb throttle would this be ok?

Like I said I want to be able to do 40mph reliably so I can keep up with traffic on every road in my city, is that possible with the parts I have chosen/my budget?

I occasionally(rarely) ride on trails, I know direct drive hubs are not ideal for uphills but what can I expect in terms of overheating and torque on a 29". The city I live in is fully flat so getting a mid drive for the 1% of trips seems kind of wasteful.

Mainly I want to know if the parts I have chosen are any good and if there is anything I should change or consider, please make sure any parts you recommend ship to the UK.

 

[E-HP]

Any reason for choosing that particular motor? Statorade and hubsinks might help, but without, at 40mph the motor will cook itself in 14 minutes or a little over 9 miles.



\\Motor Simulator - Tools


A 1200W RH212 hub with statorade will do 40mph all day long (or for 21 miles with that battery) and run as cool as a cucumber.

At 40mph, the temp stays around 83C. If you're riding among 40mph cars, you need a 50mph ebike. 40 is barely good enough if you're riding with 30mph cars, more like 25. Plus bicycles aren't safe to ride regularly at that speed, but I'm assuming you at least have a full face helmet.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

PS. Thanks for the link to the battery. I hadn't looked on their site for batteries, but the 72V 25AH 125A one built with Samsung 50S and smart BMS looks like an OK deal, if the construction is up to snuff. I need to measure my triangle though.
Charging at 12A is what caught my eye in the specs.

 

[Obelous]

Any reason for choosing that particular motor? Statorade and hubsinks might help, but without, at 40mph the motor will cook itself in 14 minutes or a little over 9 miles.

View attachment 357767

\\Motor Simulator - Tools


A 1200W RH212 hub with statorade will do 40mph all day long (or for 21 miles with that battery) and run as cool as a cucumber.
View attachment 357768
At 40mph, the temp stays around 83C. If you're riding among 40mph cars, you need a 50mph ebike. 40 is barely good enough if you're riding with 30mph cars, more like 25. Plus bicycles aren't safe to ride regularly at that speed, but I'm assuming you at least have a full face helmet.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

PS. Thanks for the link to the battery. I hadn't looked on their site for batteries, but the 72V 25AH 125A one built with Samsung 50S and smart BMS looks like an OK deal, if the construction is up to snuff. I need to measure my triangle though.
Charging at 12A is what caught my eye in the specs.

I chose crystalyte because it's one of the only motors that are: cheap, fast wind, direct drive, ship to the UK, 135mm dropout and rated for more than 1500w. I would love to have an RH212 for the cassette it's just too expensive for performing slightly worse.

As you can see with statorade the temperature is actually pretty similar 15°C difference is not bad considering its using 500w more power and going nearly 5mph faster.
Also the grin motor simulator doesn't account for flux weakening, I'm not completely sure how it affects performance lets say +5mph and now its a 50mph ebike at 1/2 battery like you said I needed. Maybe I'm wrong feel free to correct me but even so I only need 40mph for one road in my city that has that speed limit so I'm not going to be riding that that speed most of the time and only for about 1-2 minutes so I could maybe even get away with no statorade if I'm riding at 30mph, even in headwind I would have to ride for half an hour to overheat it.

 

[Chalo]

I am looking for a 3kw conversion for commuting that can do 40mph reliably for about £1300

Dubious. As described, it's a project for someone who's done this a few times already and has a very good donor bike to work with.

My frame is aluminium but my drive side derailleur hanger dropout is silver coloured so it might be steel?

Almost assuredly not. Check with a magnet, but almost every one of those things is thin aluminum, designed to break off before the frame sustains permanent damage.

For your project, you'll need torque arms good enough to hold the wheel if you didn't even have dropouts.

Seen a few horror stories about high power motors on aluminium frames so hopefully the grin torque arm should be able to handle it,

Arms. Plural. Don't mess around.

looking to add a regen thumb throttle would this be ok?

Regen is a good way to break your bike and maybe also yourself. The more torque you have in the motor, the more of a problem regen becomes. Just don't; it's asking for trouble (when the other qualities of your project are already asking for trouble).

Like I said I want to be able to do 40mph reliably so I can keep up with traffic on every road in my city, is that possible with the parts I have chosen/my budget?

Bicycles aren't good at that. There are a few exceptions but I don't believe your bike is one.