Confused! Performance Ebike newbie advice please

[Daveintheuk]

Ok, Ok, Ok!

You guys win! How about a compromise? Let’s say I want to maintain a speed of 30mph but when I feel the need have 40mph on tap.

So – New outlook;

30mph constant speed but with 40mph of power available for the odd long straight. Does this sound reasonable and more doable

Knoxie - Great post and great videos, points taken. Thanks.

So the rear suspension bike seems like a goer... Any thoughts on mounting the batteries

Ideally I’d like to mount the batteries on the bike but I’m not sure where? A rear rack would have to be a seat post mount and the max weight they can carry is around 15kg, would this suffice?

The frame seems a bit limited on space to mount anywhere

Would a handle bar bag work? Or front panniers

Last resort would be a backpack but think I’d end up cheesed off with that.

Going back to the batteries themselves – Link mentions that the cycle life is a problem... Is this a big problem? How many cycles would I get? I’ll be doing around 50 – 60 miles a week on the bike and don’t want to be buying new batteries every 3 months.

It’s still very much a head scratcher for me with the batteries but I’m starting to get it. Albeit slowly.

I take it the torque bar will have to be custom made then?

Thanks for the wealth of information... Keep it coming!

Dave

 

[stew007]

Link mentions that the cycle life is a problem... Is this a big problem? How many cycles would I get?

with the 10c/10ah lipos, using the LVC at 3.3v/cell, and an average amp draw of say 20-50 amps I would expect at least 500 cycles, possibly quite a bit more, so if you get 20 miles range, thats 10,000 miles, which ever way you look at it, miles cheaper than a car to run. This past week ive done nearly 200 miles, loving every minute of it best toy ive ever bought, the worst thing is the flies, bees and wasps hitting you in the face at 30mph, tends to sting a bit :lol:

 

[dogman dan]

You are starting to get it, I've gone 60 mph on road bikes down a hill many many times and managed to survive, but going 40 all the time is going to trash spokes and wheels fast if your roads are anything like mine. My daily commute, 4 days a week is 29 miles both ways at a speed of 20 to25 miles with full suspension and if I'm lucky, I don't have to true a wheel till the weekend. Before I went suspension, I had to replace lots of spokes and true twice a week. The point for me on the e bike isn't faster, but further. I can still peadle 30 mph, for maybe 5 minuites, or ride slow for an hour, but to do the 29 miles and have the pep to do any work, forget it. I let the e bike get me to work easy, and get some good exercise going home when it is uphill for me. If my ride was only 5 miles, I'd just peadle a roadbike. I think a good start is to build an inexpesive bike to play around on, followed later by the dream ebike when you have more experience and know better what the thing can do and what that will cost you. A cheap brushed hub motor on a lower priced but decent mtb and a good 48 volt battery is a good start for under $1500. And you may find that 30mph sustained is plenty. Belive me, a solid hour ride at 30 is a pysical and mental workout. A good battery will provide thousands of cycles for use later on a really trick bike.

 

[recumpence]

OK, I have to chime in here. Bear in mind, my build is totally custom. I have no experience with hub motors. But, speed and lipos I know.

From my point of view, 40 mph is not insane by any means. However, it is tough on components and dangerous. The big issue from my perspective is rear spokes. The weight of hub motors is hard on spoke when hitting sharp bumps at high speed. Along with that is the fact that moving from 30mph to 40mph will require at least twice the pack capacity. That being said, my bike is geared for right about 40mph. I love being able to hit that speed when I want to (I am actually gearing up for 50 soon). But, full throttle runs are the exception, not the rule. My watt hours per mile go in the toilet when I run top speed. However, from a sfety perspective, you do eventually get used to the speed and it is no longer a big deal. But, used to it or not, it is hazardous none-the-less.

As for batteries, Lipo (not Ping, those are LifePo4) are the best power desity per pound of any battery. They need special chargers, though and expensive. But, they are, by far, the best performance per pound of weight and can deliver more current than LifePo4. Also, if you keep the pack at 25% charge left and take it off the charger at 99% charge, they will last multiple thousands of recharges. Lipos are fantastic if treated this way. The rest of the bike will waer out before your cells. At 30mph on an upright bike, you will need 500 watthours at least for 10 miles (with a safe surplus left). That can be had for $500 if you look hard or $650 from many differnent suppliers). LifePo4 are safer, a bit less expensive (the same $600 will get you 750 watt hours), but are heavier, bigger, and cannot put out nearly as much amperage. I am also not sure of the longevity of them as I am not running them myself.

Lastly, above 25mph brakes are important. Above 35mph they are seriously important. Above 40, they are hyper critical! I am running a 203mm disc on my ultra light (under 50 pound) electric recumbent (I weigh 190 pounds). Repeated hard stopping from 40mph glazes my disc from over pressuring the pads. I am moving to dual calipers soon. I cannot stress brakes enough when going above 30 mph.

I am looking forward to your build, for sure!

Matt

 

[Daveintheuk]

Recumpence (Matt) – thank you!

I want a performance bike rather than a ‘pedal assist’ bike and I’ve seen a lot of you are hitting 40mph and then some within these forums.

I will be building this ‘ebike’ to a high performance specification despite all the comments. I’m not here to upset all the safety marshals or to increase my fitness levels. I’m here for decent advice on how to build this in the best way and get the results I desire.

When I get up for work a 25mph ebike will just make me pick up the car keys. However, a 40mph blast on a mean machine will give me the grin factor and keep my interest in the hobby strong.

When this project starts I’ll be sure to post up the progress and pictures as I go so I can hopefully give back some good advice in return for your help. No doubt, there be some “I told you so” moments along the way – especially if I end up swallowing a bee at 40mph! :lol:

Right I’m done defending myself about the issues of going 40mph and just want to keep this down the technicalities now.

So... regardless of whether I’m travelling at 25 or 30mph I want to build this bike capable of hitting 40mph+.

So jogging on... it’s like this so far.....

It’s the duel suspension bike

The x5 and the 72v 50a controller

Upgraded tyres and brakes a must.

And it’s looking to me like the Lipo’s to get the performance.

So I think I’m ready to start ordering the main bits from the shortlist.

I just need a few blank spaces filling in please;

The torque bar? Does it come with the hub kit? No-one’s touched on this yet?

And it seems like it’s worth ordering some extra spokes, right?

The weight of the lipos? I’m guessing around 5kg from stew007’s earlier post for around 70volts 10ah?

If the 5kg for lipos is correct I’m guessing I can mount these on a post mounted pannier rack with no problems?

And lastly – where can I learn about lipo chargers and programming the cycle assist etc? I feel I need to start getting more knowledgeable with all the kit surrounding lipos.


Thanks again guys. Tremendous input. Really, Really helpful, Keep it coming!

Cheers. Dave.

 

[Miles]

Dave,

You do realise that max. assisted speed (EAPC) is 16 mph, in UK...? If you have an accident make sure it only involves you

 

[recumpence]

Recumpence (Matt) – thank you!

I want a performance bike rather than a ‘pedal assist’ bike and I’ve seen a lot of you are hitting 40mph and then some within these forums.

I will be building this ‘ebike’ to a high performance specification despite all the comments. I’m not here to upset all the safety marshals or to increase my fitness levels. I’m here for decent advice on how to build this in the best way and get the results I desire.

When I get up for work a 25mph ebike will just make me pick up the car keys. However, a 40mph blast on a mean machine will give me the grin factor and keep my interest in the hobby strong.

When this project starts I’ll be sure to post up the progress and pictures as I go so I can hopefully give back some good advice in return for your help. No doubt, there be some “I told you so” moments along the way – especially if I end up swallowing a bee at 40mph! :lol:

Right I’m done defending myself about the issues of going 40mph and just want to keep this down the technicalities now.

So... regardless of whether I’m travelling at 25 or 30mph I want to build this bike capable of hitting 40mph+.

So jogging on... it’s like this so far.....

It’s the duel suspension bike

The x5 and the 72v 50a controller

Upgraded tyres and brakes a must.

And it’s looking to me like the Lipo’s to get the performance.

So I think I’m ready to start ordering the main bits from the shortlist.

I just need a few blank spaces filling in please;

The torque bar? Does it come with the hub kit? No-one’s touched on this yet?

And it seems like it’s worth ordering some extra spokes, right?

The weight of the lipos? I’m guessing around 5kg from stew007’s earlier post for around 70volts 10ah?

If the 5kg for lipos is correct I’m guessing I can mount these on a post mounted pannier rack with no problems?

And lastly – where can I learn about lipo chargers and programming the cycle assist etc? I feel I need to start getting more knowledgeable with all the kit surrounding lipos.


Thanks again guys. Tremendous input. Really, Really helpful, Keep it coming!

Cheers. Dave.

LifePo4 would be about 5KG for 72 volt 10 AH. Lipos would be down around 3 to 3 and 1/2 KG.

As I said, that speed is dangerous and expensive. However, it is doable. I understand what you are talking about. I got rid of my 130mph motorcycle. Now there is concern about going 40mph on my bike? Hmm, very different mindset, for sure. Besides, going down with a 50 pound E-bike is alot different than going down with 500 pounds of motorcycle (with hot engine) on my leg. Oh, in my case, I am on a recumbent. If I go down, I do not have far to fall. Road rash is my main concern.

Again, speed is dangerous. But, the speed does not concern me assuming the bike is built safely.

Remember............. Brakes.
Oh, also...........Brakes.
Oops, I almost forgot........Brakes.
Man, the more I think about this, the more items I remember. How about your.............Brakes?
Lastly...........Brakes.
One more time............ BRAKES!!!!!

Hmm, I sence a theme going on here! :wink:

Matt

 

[Daveintheuk]

Dave,

You do realise that max. assisted speed (EAPC) is 16 mph, in UK...? If you have an accident make sure it only involves you

Yes, I do, But in the same way that everyone (including me) sticks to the speed limits for cars!


And cheers matt, So puttng my feet on the ground to slow down won't suffice then?

 

[dogman dan]

Still sounds to me like you want a electric motorcycle, but hey, some folks enjoy building wheels. I just think above 30 mph bikes get the snot beat out of them. Why not just build a legal electric motorcycle and go 50 or 70 mph? It might not be much more expensive than the higest performance bike, and go twice as fast.

 

[recumpence]

Still sounds to me like you want a electric motorcycle, but hey, some folks enjoy building wheels. I just think above 30 mph bikes get the snot beat out of them. Why not just build a legal electric motorcycle and go 50 or 70 mph? It might not be much more expensive than the higest performance bike, and go twice as fast.

Not a bad idea. I am considering buying a street legal scooter and modifying the snot out of it! 80mph E-scooter anyone?!

Dave, I was not thinking about dragging your feet. I was thinking more along the lines of sticking your toe between the front tire and the forks to stop. :wink:

Matt

 

[Link]

Yeah, +1 on the brakes. You've got a disc on the front, so you should be okay.

And +1 on the 80mph e scoot. :wink:

 

[Lenk42602]

Cheers people, just superb. And hi to the other UK guy Woooooo!


There is a third option – if you guys think that both bikes are unsuitable for this project I would look at buying another specifically for this build.

So what do you think?

And any other thoughts for the batteries? Do the lipo’s sound like a winner

And any input on where I get the torque bar from? Does it come with the motor

Keep your thoughts coming! Cheers.

Hey Dave,

Good to see you are raking the time to design your machine from the onset, rather than potentially try to shoehorn what you have on hand to meet your design goals. Now, given your intent to see 40mph continuous, here is my .02...

As detailed in earlier posts, the stresses placed on bicycle components @ 30mph versus 40mph continuous increases exponentially. At 40, it becomes increasingly important to make sure your set up works as a system, and does not put the individual components beyond the range of their fatigue cycles...

Handling - weight distribution becomes a very key consideration - where you put the battery packs, overall balance of the bike based on weight of rear hub motor, front fork + batts all will determine the feel of the bike. I designed my last system around the batteries being in the center of the bike frame first, and worked my way out from there..

Chassis performance - the frame - always, we are trying to make a bicycle frame, originally designed for very small amounts of human power based output, and resultant fatigue /stress to frame areas and components isolated around a pedal powered machine reaching max speeds due to gravity - not the drive wheel...( head tube reinforcements, frame tube butting,etc)....brakes - but seems like you get that.....

If you are really committed to 40 mph cont. You should be equally committed to design, and making sure your specs work together as a system - and not at the upper edge of its limits. For this reason, I would not go with either of you frame options... You would be better off with a FS DH specific frame, center mount batts. I use LiPo on my bikes, btw.

peace,

Len

 

[stew007]

I think the 5x series motors come with torque arms already fitted, but best to give ebikes a ring and see, If your roads are smooth, unlike the bumpy ones here, then I think 40mph would be fine, My bike at 35mph feels good, just make sure the spokes are tight, the wheels are true, your brakes/wheels are centred etc. I ride 50/50 bumpy/smooth roads, and after tightening the spokes on my hub motor (they were far too loose from the factory) this last 250 miles the wheels are still true, But the setup is light weight, light batteries (3.6kg), light motor, and I weight 11.5 stone so not a high load on the wheels. Thats another + point for the Lipos, they keep that weight right down.

But I cant see much wrong with an x5304, and a 21-24 cell lipo, you dont have to ride flatout all the time, thats what the throttle is for :lol: , a measure of common sense goes along way, You will get used to how the bike handles, the best way to find it's limitations is by riding it, and for the first 100 miles take it easy, keep the speed down, and get the feel of it, try some heavy braking to find the limitations of your brakes too 8) And if it's an ali bike, keep your eye on the welds, the raleigh mtb I ride is steel, strong with good welds so not much too worry about. if you feel you are going a bit too fast and it begins to feel unsafe, then slow down a bit :lol: We can all go out and buy a honda Fireblade, but we dont have to go everywhere at 170mph, the safest road users are ones who use common sense, have safety in mind and know the limitations of the vehicle they are operating. If I was building another bike it would be an x5304 with 88.8v!! I say go for it mate, it's all there waiting for you.

 

[recumpence]

Absolutely!

Great advice. You will probably find yourself running 35mph most of the time. I have found 35 to be a very happy speed. It is plenty fast, yet relavtively safe. When I crank it up to 40, there is a noticeable difference in stability. Not huge, but definately there.

If I had your design criteria, I would set it up to hit 42 or 43 mph absolute max speed, then run it 35 to 38 mph most of the time. That will give you a bit of overhead so you are not running it at max throttle all the time.

Anyway, I would highly recommend Magura Gustav 210mm brake for the front. Go with the best, Man!

And, yes, ballance is critical at those speeds. You should mount the cells in the center of the frame, not behind the rear wheel.

Matt