I had a particularly pleasant bottle or two of Pino Grigio this afternoon and decided to design an electric mountain bike.

It needs to be useable without power so no heavier than a down hill bike
It needs to be able to go up hill and down hill at a good speed. 30mph down hill, 15mph uphill
It needs to have power for an hour

Now the bits I don’t know

How much does a downhill bike weigh?
What rpm at the axle for 10, 20 and 30mph?
How long does power last?

Okay, this is currently a thought process rather than a plan but please share your thoughts.

Also wondering about mechanical layout of the motor and battery. Any thoughts on that welcome. I don’t want wheel centre motors as they aren’t great for weight position and handling.

The great thing is that because we don’t necessarily need to build it, we don’t need to be constrained by current bike design. I am stuck on an iPad at the moment do can’t post useful pictures

A quick google have revealed loads of people doing this sort of thing on youtube, even with fatties!

[video]https://www.youtube.com/watch?v=CKk3i4CmLlg[/video]

[video]https://www.youtube.com/watch?v=o5v17hK3Va0[/video]

Definitely a badass dongle mod thing.

Use a decent bike and mount a Bafang BBS02 at 48v (or more) – should be 750 watts which is enough for just shy of 30mph. Pick a bike that will allow you to mount the battery in the main triangle for best weight distribution.

You may need to toughen up the cranks, so something from Middleburn as they are square taper.

Be prepared to spend lots of money on a lightweight high capacity battery.

…no heavier than a down hill bike… 15mph uphill…
It needs to have power for an hour

Nah… Batteries = mass

To be able to blap your way uphill at ~15mph and to do so for an hour, you’re going to need a significant quantity of batteries, so you’re probably going to exceed your weight goal…

Why not just do the same as everyone else who wants to get their gnarr on without pedalling and buy a crosser?

http://www.stealthelectricbikes.com/

https://instagram.com/p/88USJ8vEcN/
Just needs a motor and it’s ready for armchair forum types

These Spesh ebikes sound incredible from the reviews I’ve seen and don’t look too bad. Just copy one of those.

Oh and a DH bike will be in the 35-40kgs range so you’re probably looking at 5kgs worth of batteries/motor/control electronics/whatever else you need to make it work. That’s not going to get you 30 miles at 30mph.

Good luck.

eh?

Modern DH race bikes have been built as light as 30lb and pretty much no one races on anything over about 42lb anymore.

Oh and a DH bike will be in the 35-40kgs range

😆

Think someone’s got pounds and kgs mixed up. Even the early 00’s hucking monsters (Karpiel, Canfield and Brooklyn Machine Works) were 25ish kgs.

Think someone’s got pounds and kgs mixed up

Yep 😳 wrong suffix on the numbers.

helpful1 – Member
eh?
Modern DH race bikes have been built as light as 30lb and pretty much no one races on anything over about 42lb anymore.

Over-react much? 🙄