Stealthy lipo filled custom frame

[Hyena]

Hey guys,
As I continue my pursuit for the perfect ebike I've decided to go down the custom frame route.
Stealth is really important to me and I want to keep it looking as much like like a standard heavy duty downhill bike as possible.
I love my stealth fighter but it does stick out a bit, and with a lipo pack powered it it doesn't need to be as big as it is.

So, enter my custom frame plans. I'd like something that is smooth like the fighter with plush suspension that floats over the rough stuff but at the same time I want to minimise it looking like an e-dirt bike.
This is what I've got so far, a cheap diamond back full sus frame I've had cut and shut by timma2500.
The downtube neatly holds 18S2P lipo and the top tube could easily accomodate another 18S1P if it was made slightly larger
So all up it'd take a 15ah battery which I think offers great compromise between range and speed.



The next step is to make something completely from scratch but with fairly simple rear suspension design. So the triangle would probably be along the lines of the above chopped DB but with a dirt bike style rear shock set up minus the all the fancy linkages that modern day DH bikes all seem to have. The swing arm would be kept simple and because it's custom I can make it as wide as I like to fit silly large motors on there

Any thoughts / suggestions / input on the design ?
Once I have a sucessful running model and do some stress testing on it I'm going to look at having a run of them made to offer up for sale.
So now is your chance to have some input in what you'd like to see
If the phasor bikes were made here in Australia (ie no huge shipping costs to get them here) and could be run as the bare oversized frame without the side covers I'd probably just go with those. But they don't and they are, so it's DIY time

 

[Samd]

+1 sub'd.

Love yer work.

 

[adrian_sm]

What do you think about hiding the controller inside the frame as well to keep the stealth look.

Would probably require ripping the normal case off, and heat sinking to the frame instead, but would really add to the stealth look.

 

[Hyena]

Yep, already though of that - I was thinking 12 fet or even 18 fet controller in the seat tube, heatsinked to the whole frame

So basically the down tube and seat tube would be made of pipe around 105mm wide with the top bar either being the same (for max battery capacity or smaller to accomodate a single file row of lipo packs. OR the seat tube could be kept smaller / thinner and the controller could go in the top tube or an oversized reinforced looking sort of front end up around the head tube (like the above picture but slightly bigger)
There'd be still room to fit 2 6S packs in the top bar with it like that, so you could have a 24S2P pack powering it, which woudl be pretty cool
or 12S4P for those not after so much speed/power.

Here's a pro MS paint indication of a possible set up I was thinking about

 

[full-throttle]

Here's a pro MS paint indication of a possible set up I was thinking about

Won't work - extreme falling rate. You'd have to mount the shock to the down tube instead.

Before you dive into this you should really consider getting a quote on liability insurance. It may surprise you

 

[Phoebus]

That's a great looking prototype.

One idea is to make the head tube 1.5" diameter. This allows one to run a simple AngleSet, and thus adjust the head tube angle to their liking.

 

[adrian_sm]

Idea #2: Integrate in a "standardised" bulk charge and balance connector into the frame.

 

[Hyena]

Won't work - extreme falling rate. You'd have to mount the shock to the down tube instead.

See that's the part I need help with!

Before you dive into this you should really consider getting a quote on liability insurance. It may surprise you

Yeah if I'm going to sell them I'll have to look into all that sorta stuff. At this stage I'm making it for myself but with the view to reproduce it if there's sufficient interest. It will be made strong enough not to fold in half (I'm thinking 1.6mm cromo) but at the same time maybe I should get people to sign a "I won't sue hyena if I fall off this thing" kinda document I'm only talking small scale anyway, a few here and there to the likes of you guys, not competing with stealth or A2B or anything publicly. I can just see that when it's all finished a few people are going to say "hey man that's awesome, make me one!" and if it's not too hard, maybe I will

One idea is to make the head tube 1.5" diameter. This allows one to run a simple AngleSet, and thus adjust the head tube angle to their liking.

Cool, that's easily done

 

[adrian_sm]

Idea #3: Position the bulk charge connector such that it can be easily used as a extension pack plug in point.

I like Keplers idea of using a Topeak Aerowedge tail bag, or handlebar bag to stuff some extra Ah in when you plan on going for that longer(or harder) than normal ride.

 

[Hyena]

Idea #2: Integrate in a "standardised" bulk charge and balance connector into the frame.

Most definately! That goes without saying
I'm thinking a 36 pin centronics plug for general charging + a seperate main lead for high current bulk charging. Or maybe just a smaller centronics plug for balancing when required with a main 6 pin bullet connector plug that is put into series to discharge and parallel to charge.
I could also build in a small 120w modded laptop charger for slow top up charging from any 240v source. It wouldn't really be fast enough for opportunistic charging though - more so if you were riding somewhere overnight and had somewhere to recharge it but didn't want to lug the charger along too. Or the 'camping edition' that could recharge from a 12v car battery

Re: idea #3 - yeah easily done too

A DCDC converter for powering lights also goes without saying. I'd probably throw in a USB jack for good measure too - I'm always needing to recharge my gopro or phone when out and about

 

[adrian_sm]

A DCDC converter for powering lights also goes without saying. I'd probably throw in a USB jack for good measure too - I'm always needing to recharge my gopro or phone when out and about

I like that idea. In fact if you settled on a specific light like the magic shine you could just put in the correct jack up the front of the down tube for a very neat light installation.

Idea #4: On/Off Button/Switch.
You really want to be able to power everything down at once if possible. Especially if you have DC-DC converters adn the such. I killed a cell in my headway pack from leaving the DC-DC on for too long when I wasn't using the bike.

 

[full-throttle]

See that's the part I need help with!

http://www.bikechecker.com/

 

[adrian_sm]

A DCDC converter for powering lights also goes without saying. I'd probably throw in a USB jack for good measure too - I'm always needing to recharge my gopro or phone when out and about

If you are going to integrate a DC-DC you could use this to power up your controller, and get rid of the crappy voltage divider thing on them. This will make them more universal in voltages they will be happy with. Might also make it easier to implement an On/Off switch.

 

[adrian_sm]

Idea #5 - Hot Swap Battery

Note sure if I like this one or not, as it may compromise compactness, or split battery packs in the frame. But..... how about making the enclosure size and access hole such that you could remove the whole battery in one hit easily. This could allow people to have two battery packs for those times when they really don't want to wait to charge up.

 

[tofuuu]

Love what you are doing! Hopefully that cheapie frame is able to hold up to your testing!

I have a few ideas

Make it so that small wheels dont look absolutely ridiculous on the bike. Some of the recent fs + small wheels builds are a bit on the clown side, maybe adjust the clearance of the bike or play around with the geometry of the frame or make it with the option of running a smaller wheel to begin with?

Integrate rear rack into the frame like the A2B. It will be handy as a mudguard or alternate place to put controller/batteries and also will make the bike more useable day to day and less grief when somebodys seatpost rack cracks the frame. It might make the frame weigh a bit more and require some welding but everybody will love you for it. Everybody.

Wider rear dropouts? You sell alot of high power kits, do you think theres much to gain in having more room for gears or fitting a bigger engine? Might be something to think about.

 

[sico]

Before you dive into this you should really consider getting a quote on liability insurance. It may surprise you

I think a liability waiver is the perfect way to deal with this for sphere customers. We should have a standard form stickied to the top of the for sale section and sellers can adapt it to their needs.

Loving the frame too dude.

 

[Hyena]

http://www.bikechecker.com/

Perfect, thanks mate!
I remember seeing that (or something similar) before but couldn't remember what it was called.

If you are going to integrate a DC-DC you could use this to power up your controller, and get rid of the crappy voltage divider thing on them. This will make them more universal in voltages they will be happy with. Might also make it easier to implement an On/Off switch.

Yeah that's an option I suppose, not something i've given alot of thought to as it's not a burning issue but it's certainly doable. I'd most like have the DC-DC converter set to directly drive the LEDs though so the voltages may not be compatible. Speaking of LEDs, if going for all all out ultimate ebike I'd integrate tail lights directly into the frame too - either somwhere on the swing arm or build into the back of the seat tube or something.

Idea #5 - Hot Swap Battery
Note sure if I like this one or not, as it may compromise compactness, or split battery packs in the frame. But..... how about making the enclosure size and access hole such that you could remove the whole battery in one hit easily. This could allow people to have two battery packs for those times when they really don't want to wait to charge up.

I'm not TOO enthused about hot swapping batteries. I'd probably rather have an easily added booster pack on a seat post rack or something but again it's not out of the question.
I was thinking I want to try and keep the side and top profile of the bike as neat as possible, and minimise welding by folding as much of the frame as possible. Others making these sort of monocoque frames seem to have all the pieces individually cut and then weld them all together - not sure why that is. I'd be keen to hear from anyone in the know if there's a reason for this (eg structural strength, flex etc)
At the most I'd only have only one removable side panel but I'm going to look into the feasibility of adding the batteries from the bottom. So it's the underside of the down tube that bolts off. It'd probably use a gasket or large o-ring or something to seal it from water getting in but I don't think it'd be a major issue. This would give a neater overall appearance and while it'd mean flipping the bike upside down to insert the battery pack, I'm not intending for it to be regularly replaced or require accessing. The other option if I just went with a single oversized down tube for the batteries would be to have a door on the bottom to add them (so the bottom bracket shell would actually be above or below the down tube rather that at the end of it like normal)

Make it so that small wheels dont look absolutely ridiculous on the bike. Some of the recent fs + small wheels builds are a bit on the clown side, maybe adjust the clearance of the bike or play around with the geometry of the frame or make it with the option of running a smaller wheel to begin with?

Yeah I'm not a fan of the small wheel look and it goes against the low key appearance I'm trying to achieve with this bike. 24's, quite possibly but not 20" or less. If I DID do that it'd probably need to set up the swing arm to give it a dirt bike type stance which again is not what I'm after. I would like something like that for offroad use but the aim of this bike is for general use on and offroad - but not hardcore downhill type abuse. Rough terrain at speed and little jumps, yes, but not riding off small cliffs

Integrate rear rack into the frame like the A2B. It will be handy as a mudguard or alternate place to put controller/batteries and also will make the bike more useable day to day and less grief when somebodys seatpost rack cracks the frame. It might make the frame weigh a bit more and require some welding but everybody will love you for it. Everybody.

Yeah that's something else I'd already considered too
Basically having one long top tube that extended back past the seat post and kept going to form the basis of a rack. If i did this I'd have a door on the end to insert the batteries from behind and have a short seat tube suspended above the top bar. I'd have to do it such that it didn't interfere with teh suspension travel though.

Wider rear dropouts? You sell alot of high power kits, do you think theres much to gain in having more room for gears or fitting a bigger engine? Might be something to think about.

Definitely - they will be set up for 150mm or maybe even wider axle spacing. My fighter actually has ~160mm spacing which is an odd number but it's no issue with any motor, you just have an extra set on nuts on the inside of the swing arm and tighten them out as you tighten the outside ones in. It would also allow you to run a very wide rear motor and still retain a multispeed freewheel (not that you'd need it with a motor that's too wide to fit normal gears )

 

[Hyena]

I think a liability waiver is the perfect way to deal with this for sphere customers. We should have a standard form stickied to the top of the for sale section and sellers can adapt it to their needs.

Yeah it's nice to think we're all brothers in our EV pursuits but sooner or later some asshole is going to try and sue someone for something unreasonable.
I was just talking to Philistine about this on the weekend actually.

 

[adrian_sm]

Others making these sort of monocoque frames seem to have all the pieces individually cut and then weld them all together - not sure why that is. I'd be keen to hear from anyone in the know if there's a reason for this (eg structural strength, flex etc)

You can't easily fold up an fully closed section such that you just weld one edge. Even deep U channels are tricky in a brake press

Other manufacturing options are:
1) Using an extruded tube, like the ones you were sourcing for battery enclosures. You could use one of those as you down tube.
2) Hydro formed tubes. Start of with a normal tube, then blow it up inside a tool to the size/shape you want. But too expensive for small quantities.
3) Fabricating from individual parts, either flat or formed. Gives good freedom in geometry, and is cost effective for small batch production.

At the most I'd only have only one removable side panel but I'm going to look into the feasibility of adding the batteries from the bottom.

Why not use one of your extruded aluminium sections you are sourcing as your down tube, and machine out the access hole. On a slightly related note Specialized recently annouced an ebike that uses the downtube to store batteries, manages to keep the stealth look quite nicely, but probably not the sort of watt-hours you want to jam in. :lol:

 

[Hyena]

You can't easily fold up an fully closed section such that you just weld one edge.

Oh yes I realise that! I was hoping to maybe do it in 2 halves btu even that might be too hard if it's not a basic shape.

1) Using an extruded tube, like the ones you were sourcing for battery enclosures. You could use one of those as you down tube.

Yeah I thought of that, though I want it to be cromo and I haven't found a place that can make the size I need. It'd certainly make shorter work of the project though!

On a slightly related note Specialized recently annouced an ebike that uses the downtube to store batteries, manages to keep the stealth look quite nicely, but probably not the sort of watt-hours you want to jam in. :lol:

Yeah I've seen that - looks neat for what it is but yeah, needs moar power
I was thinking a U channel down (or top) tube could work for easily swappable batteries though - have the frame made with that section open then you drop in the battery, which has metal top that completes the structure of the tube when bolted or clamped in. An open top tube would be better in this sense and if the rest of the frame was made sturdy enough it may not be necessary to bolt it in too comprehensively if it's not adding alot of structural support.

The other thing I'm thinking might be wise is to make my first frame a hard tail to sort out any production issues and then worry about moving onto a full suser afterwards. I'd probably make the rear end look like a swing arm from an asthetic point of view rather than the usual hardtail triangle shape.

 

[adrian_sm]

Having a fully open U section will be torsionally pretty weak. Especially if you had both top and down tubes as U's. The more you can box off the better.

The other thing I'm thinking might be wise is to make my first frame a hard tail to sort out any production issues and then worry about moving onto a full suser afterwards.

+1

I'd probably make the rear end look like a swing arm from an asthetic point of view rather than the usual hardtail triangle shape.

-1 Really? I would just stick with what works, rather than pretending to be a full suser.

 

[Hyena]

Having a fully open U section will be torsionally pretty weak. Especially if you had both top and down tubes as U's. The more you can box off the better.

Sorry, I realise the way I wrote that made it come across wrong - I didn't mean the whole top open but it'd need a decent slot in it. Unless I made the lipo pack to feed in in sections (like the current proto frame does)

-1 Really? I would just stick with what works, rather than pretending to be a full suser.

I was thinking along the lines of somelike like the blacktrail. That would suit the square tubed main frame I'm proposing.

 

[Hyena]

Hard tail musings based on the black trail using a standard triangle design with extended top tube for more battery - looks a bit boring.




This on the other hand looks pretty cool I wonder how thick a material I'd need to use to have this not crumple ? The flex could actually be good for soaking up the bumps :lol:

 

[Xanda2260]

Ooh, that looks niiiiice! Stick me down for one if it ends up like that!

 

[Phoebus]

Re: Liability Insurance

The following is my amateur understanding (I am not a lawyer/professional, have no special knowledge here):

In the US at least, the person needn't decide to sue you/vendor/operator. Indeed, since almost all individuals are insured themselves, they have little to no incentive to.

Rather, the insurance company, who is footing the bill for health care, may decide to sue you/vendor/operator. If the injured party doesn't aide the insurance company in their suit, then coverage will be denied.

So it's a good idea to get liability insurance - at least stateside. Not sure what the story in AUS is, but it's probably similar... some people do have private insurance there as well, yes?