Ok i'm new to this e bike stuff but have spoke with few mates who built their own rigs

[howier]

So i am buying a full on dh bike weight wise it's gonna be around the 40lb or just short with triple clamp forks.
my main issue is the rear wheel weights of anything above 1000w so after chatting with my mechanic/electrician mate, he advised me to just get a lightweight 250w rear wheel around 4kg and a 48v 20amp battery as he reckons you can put loads more power through the wheel than the stated actual wheel wattage, thus a far better range, a bit faster and lighter to boot.

so anyone know otherwise before i bite the bullet and order a rear wheel btw it's gonna be a 26" max 500w, possibly 250w, so any suggestions as to the lightest model available, also where to purchase the best, lightest, cheapest batteries, i'm not asking much, lol.

thanks in advance

 

[markus datgloi]

Do I understand that your dh bike is already 40 lb ? A modern carbon DH mtb (not e-mtb !) weights approx. 34 lb, a 48v 20ah battery and a rear wheel hub drive are each approx. 15 lb. The total comes somewhere around 60-70 lb ...?

A bike like this ? Note: the battery is in his backpack... to keep the bike's weight low ?


Could be fun building it, and filming it, but not driving it.

 

[Neeko DeVinchi]

Hi @howier,
Where are you based so I can point you to reputable online retailers who you can consider.

In addition, it would be helpful if you could provide a picture of your rig so we know what you're working with.

Ebike conversation isn't as simple as most people believe. It comes with its own challenges as you are essentially retrofitting components which may not have been thought of when the manufacturers designed the frame.

In addition, whilst hub motors are working horses of motors, I personally would lean more towards a mid drive unit as the added weight of any hub motor would have an effect on your rear suspension. Notwithstanding the fact using torque arms to fully secure a hub motor onto the rear drop outs will result in more messing around should you puncture the rear tyre or, wish to swap.

Granted, my expertise full more in line with building dedicated emtb frames but I have assisted those with ebike conversations in terms of battery selection and battery/controller placement.

Again, take clear pictures and confirm where you are based and I'm sure myself and others can help??

 

[howier]

Do I understand that your dh bike is already 40 lb ? A modern carbon DH mtb (not e-mtb !) weights approx. 34 lb, a 48v 20ah battery and a rear wheel hub drive are each approx. 15 lb. The total comes somewhere around 60-70 lb ...?

A bike like this ? Note: the battery is in his backpack... to keep the bike's weight low ?


Could be fun building it, and filming it, but not driving it.

Lol i've yet to buy the bike but looking at downhill rigs with triple clamp forks maybe ill go lightweight single crown forks to save kg's, i've had many carbon bikes last one was 2017 saracen kili flyer elite carbon with every nut and bolt titanium 12kg but lightest one was alu german made 1998 steppenwolf tycoon cr 11.5kg and made 19 years earlier, so not buying a modern bike going for a cheap build way below 1k with everything, not arsed about doing daft speeds just a capable bike around 20mph would be enough, yes battery will be in backpack and rear wheel as light as is possible.
i'm atm waiting on a call ref: 2009 giant glory dh with wc rockshox and shitloads of stuff/spares only thing missing are wheels.

i reckons the whole bike complete with e rear wheel around 40lbs - 43lbs complete.

 

[howier]

Hi @howier,
Where are you based so I can point you to reputable online retailers who you can consider.

In addition, it would be helpful if you could provide a picture of your rig so we know what you're working with.

Ebike conversation isn't as simple as most people believe. It comes with its own challenges as you are essentially retrofitting components which may not have been thought of when the manufacturers designed the frame.

In addition, whilst hub motors are working horses of motors, I personally would lean more towards a mid drive unit as the added weight of any hub motor would have an effect on your rear suspension. Notwithstanding the fact using torque arms to fully secure a hub motor onto the rear drop outs will result in more messing around should you puncture the rear tyre or, wish to swap.

Granted, my expertise full more in line with building dedicated emtb frames but I have assisted those with ebike conversations in terms of battery selection and battery/controller placement.

Again, take clear pictures and confirm where you are based and I'm sure myself and others can help??

Hi im in cheshire, and i am a welder/fabricator /engineer so nothing is an issue relating to the fitting, ideally i'm trying to get horizontal rear dropout swingarm bike to get rid of main issue of torque pulling wheel off centre, sideways.
i've looked at mid drives and really like them but again the downside is the price compared to rear wheel diy kits, so i'm sticking with rear wheel drive atm.

so after checking out the glory dh frame, looks like ill have to get angle grinder out for horizontal rear dropouts, can then fab something up to adjust wheel alignment like on a motorcross bike.

thanks for all replies mucho appreciatted

 

[Doug Stampfer]

This is gonna be one of those fun threads, I can feel it.

 

[howier]

This is gonna be one of those fun threads, I can feel it.

may go for this instead just because of rear dropouts, will save me a lot of hassle too.

 

[markus datgloi]

Here is my Giant Coldrock ATB with 26" max 1000W hub drive that is currently used as a road bike.

Difficult to see but I had to make brackets (torque arms) to keep the 1000W Goldenmotor hub drive fixed/locked in place in the dropout. Without the brackets to fix/lock the wheel, the wheel nuts will loosen. The drive has also regenerative braking which adds to loosen up the... ? The large chain ring (75T) is of a recumbent bike and is used to keep the cadance low when driving ~45+ km/h. Goldenmotor has locked the max speed at 45 but I have had it just over 50.

How does it drive ? On straight paths perfect, in corners as if the rear wheel wants to go in the opposite direction... horrible instable. The old brakes are hopeless but thanks to regenerative braking it brakes well. ? And I am lucky: no puncture of the rear tyre yet...

Neeko has good advice, the most important one is: go mid drive.

 

[howier]

Here is my Giant Coldrock ATB with 26" max 1000W hub drive that is currently used as a road bike.

Difficult to see but I had to make brackets (torque arms) to keep the 1000W Goldenmotor hub drive fixed/locked in place in the dropout. Without the brackets to fix/lock the wheel, the wheel nuts will loosen. The drive has also regenerative braking which adds to loosen up the... ? The large chain ring (75T) is of a recumbent bike and is used to keep the cadance low when driving ~45+ km/h. Goldenmotor has locked the max speed at 45 but I have had it just over 50.

How does it drive ? On straight paths perfect, in corners as if the rear wheel wants to go in the opposite direction... horrible instable. The old brakes are hopeless but thanks to regenerative braking it brakes well. ? And I am lucky: no puncture of the rear tyre yet...

Neeko has good advice, the most important one is: go mid drive.

View attachment 65147

Simple enough on the Kissit frame to keep wheel in situ and not an issue loosening nuts i'll toque to correct setting then either use lock washers or two wheel lock nuts either way it's not something that's gonnna faze me, yes i agree prefer mid drive but this is a cost effective way of having the bike with the travel i want whilst still keep costs to a bare minimum, should have the complete bike up and running within a month.

cheers for advice, but one thing i do not want is a 12kg lump for a back wheel, lol

 

[daveswin60]

I did the same thing and after a 20 mile ride I stopped and felt the hub it was red hot so sold the hub before it failed and purchased the proper hub for my 48v battery and now its fine only gets warm on long rides

 

[Supra]

I used a 2006 giant trance frame, tszd mid drive motor , 27.5 double crown forks, weighs 22kg, goes insane , i sold my scott genius carbon, this goes downhill just as good, and twice the fun. Needs osf firmware for real mtb feel.