Descendence bikes open-source electric bike frame

[madm3chanic]

you just gotta be careful with the width around the bottom bracket area. any wider than about 120mm too close to the bottom bracket and the sprocket or the cranks will hit it (even with a 100mm BB shell the space between the insides of the cranks is nowhere near 150mm) which is why you can see on the raptor the battery cavity doesnt get that close to the bottom bracket. my only concern there is that its gonna raise the COG a fair bit by not allowing any cells to go down near the bottom bracket.

done a fer renders of the front triangle as per that sketch i did-




havnt really worked out any nittygritty like how to join the tubes around the bottom bracket area, just trying to get a feel for the aesthetics and configuration like this.
personally i really like the distinct transition from the frame to the battery box; i think thats the main reason i like this design aesthetically over the first design i did. with the distinct separation between the box and the frame, it kind of makes it look less bulky than on the other one with the battery cavity as part of the main structure.

PS doen anyone know why sometimes the forum displays pictures inline, and sometimes just does them as a download link like above?

 

[Tench]

Motus will be flattered! I see you have shifted from the Stealth clone to a Motus layout.
You are clearly very able to manufacture nice frames, but your design needs to be more original and less copy!

I read you wanted to do a mid mount frame, its not so hard especially if you have a blank canvas, much easier than trying to fit a mid drive within the confines of an existing frame, but even that is quite a simple task.



My build 2 below has more on that bike.

I am about to launch a new production frame myself, the first 5 frames are very close to completion

 

[madm3chanic]

Motus will be flattered! I see you have shifted from the Stealth clone to a Motus layout.
You are clearly very able to manufacture nice frames, but your design needs to be more original and less copy!

I read you wanted to do a mid mount frame, its not so hard especially if you have a blank canvas, much easier than trying to fit a mid drive within the confines of an existing frame, but even that is quite a simple task.

My build 2 below has more on that bike.

I am about to launch a new production frame myself, the first 5 frames are very close to completion

hahaha pfft i detect a certain amount of irony in that originality statement after seeing the spec bighit chop...any less original and it'd be a clapped out old giant dh team conversion

but seriously, it is very hard to be original in a world when literally everything has been done before, i stopped worrying about that sort of shite ages ago. if you really keep going down that path to its logical conclusion, you'd walk around wearing a potato sack with a aluminium foil hat on your head.

my frames get continuously coppied all the time, iv even had pat. pending challenges. goes around comes around and all that...

 

[Tench]

You have a PM, with a sneaky peaky pic of my new frame design 8)

 

[madm3chanic]

so what kind of range do you lot think ill get with a 72v 20ah LFO battery pack with the controller set to 40a discharge? i know that john bozi gets about 35km from his 72v 12aH but they're lipo's and i dont know what current he's running them at. anyone else had any experience with this big a battery pack?

 

[Ohbse]

Depends on the terrain and to a large degree your average speed. To give you an idea I get around 24km of hoonage out of 10ah of Lipo. Lots of stop start, full throttle to 55-60km/h till the next light, loads of hills. That's with a 65amp limit, though cruise is lower than that obviously.

Riding more sensibly with a lower power limit I would expect you'll comfortably get 60km or 35+ miles.

How far do you need to go?

 

[madm3chanic]

i need to go about 55km thru pretty much all hills. they ar quite small hills (if you've ever been to perth you'd understand) but not much of it is level. and of course the idea of a bike like this is certainly not to be restrained so ill no doubt be riding as fast as i can at all times.

i am wondering if i should go up to the 40152E size cells to get the pack up to 30aH. they're a fair bit bigger but it'd only cost about $200 more for the whole lot, so im thinking its probably worth it. that way id definitely have the juice for it, maybe a bit more amps could go in there.

 

[Tench]

While out with the wife on her Euro legal bike and me riding my Bomber with its 72v 20ah life pack we would travel at 17mph ish 27kmh. At this speed on flat ground with gentle pedal assist the Bomber would give 80 miles (128km) to a charge. The distance you can cover will be very dependant on your speed and terrain, but yes you could do it. I could even travel a 40 mile round trip at a very decent pace if I kept one eye on economy.

As a basic rule, I found that if you can consume less watts per mile than you have AH then your range will be about equal to your voltage, so at 20w/m a 20ah pack at 72 volts should get you 72 miles.
If the consumption in watts per mile is double the AH capacity your range will be half the voltage.

 

[John Bozi]

I don't know if 72v 40amps is going to be enough to keep you going at over 55 km h up hills. But if they are the types with lots of run up it won't matter.
I think you mentioned headways like the bomber batteries - man they are expensive at the 20ah mark unless Ive missed something. Stealth sells them for over $2000 good for 600 charges they advertised.

IF you buy your first box with bms then you have the structure to copy and learn how to replace the dead one.... shipping the whole $2k box with weight and insurance is big bucks.

 

[madm3chanic]

I don't know if 72v 40amps is going to be enough to keep you going at over 55 km h up hills. But if they are the types with lots of run up it won't matter.
I think you mentioned headways like the bomber batteries - man they are expensive at the 20ah mark unless Ive missed something. Stealth sells them for over $2000 good for 600 charges they advertised.

IF you buy your first box with bms then you have the structure to copy and learn how to replace the dead one.... shipping the whole $2k box with weight and insurance is big bucks.

they really aint that bad- tonight i received a quote for 44 x 38120s cells (3.2v 10ah), 44 busbars, 3 BMS boards and a supervisor module for $1350AU (picked up from perth from EV Works). i really do consider that very reasonable for a battery of that capacity and quality even if i do have to put it together myself- no shitty chinese greymarket stuff, and id have the warranty and support that you'd get from anything local. im also looking at the same battery from 15ah cells, it'd probably be about 20% bigger physically but only about $300 more for the entire lot. the main thing that makes a big difference to me is that i dont have to be paranoid charging them, and dont need to do all that individual balancing crap that you are suppost to do with lipo cells. just plug it in and go drink beer and go to sleep.

regarding the amps, im thinkin about the 15ah cells cause then id get 30aH and could realistically run then at 60a, then you really got a machine that can move. iv been talking to Dillenger (i used them for the kit for my last ebike build, super helpful fella's) re. a 5000w hub and controller unit, they seem to have the kit fairly well sorted but it isnt as expensive as the build-it-from-parts-yourself kinda route you'd have to go to get a decent crystalyte/kelly controller setup or something like that.

i have done a HEAP of emailing chinese suppliers on alibaba, aliexpress and ebay for both LFO and lipo units, and seriously it all seems to be the same story- nothing ever checks out the first time. the sizes are rarely as advertised (they always make "typing errors"), the prices go up or down, they cant make them from this type of cell cause they ran out so now they gotta use this other cell, whatever. it always seems kinda reasonable when you're talking to them at the time, but after a while you sit back and wonder why none of them can actually just go "yes that'll be $1000 all up and its exactly as advertised". na frock that, i aint sending thousands of dollars to some friendly but shady character offshore. im stickin with local, if something doesnt work i can just go back and have a chat.

 

[John Bozi]

sounds like youve got it worked out, if you can go 15ah cells I think thats your best bet considering the 40km trip you spoke about.

I do miss my 48v 10ah headway pack, as you say plug in, drink beer and fall asleep.

Only problem was too bulky and not enough grunt. I couldn't get it much over 50 kmh on long flats with hookworms.

I am looking into a 20s bulk charger for my 21s batteries. That would be charging to 84v or 4v a cell. Quite a huge safety margin for rogue cells.

 

[peters]

You have a PM, with a sneaky peaky pic of my new frame design 8)

Aren't you afraid that madm3chanic will return with a third design, much reminding to yours? 8)

 

[madm3chanic]

You have a PM, with a sneaky peaky pic of my new frame design 8)

Aren't you afraid that madm3chanic will return with a third design, much reminding to yours? 8)

you're a bit of a cock arnt you?

 

[madm3chanic]

anyhow...cocks aside, i think its definitely worth reviewing the best aspects of each frame out there and the shit bits too before i get too carried away with my current design. i think its a good idea to design the frame around a removable battery box, i wanna allow the battery box the option of being 150mm wide internally, and adjustable geometry seems to be coming up quite a lot.

anything else anyone would like to see?

 

[madm3chanic]

wow i just looked at peters thread and i gotta say i am humbled at the quality of his work; if you havnt seen it i suggest you go and take a peek. maybe something was lost in translation in his post re. the frame looking like tench's and maybe i reacted a little prematurely, but holy shit that man spent some hours fabricating his bike.

im not sure i actually like the aesthetics of it in its finished form all that much but that is entirely beside the point; the way he put together that swingarm and seam welded so many pieces together for that frame would have been so damn time consuming and shows so much dedication to what he wanted to create for himself. bravo sir.

 

[Gregory]

Good on ya madm3chanic, I don't think he was meaning to be in your face, it's easy to misread internet posts.

Great to see yet another west aussie on here doing custom work. Make me a frame you talented bastard and we'll ride the goat track!

 

[madm3chanic]

Good on ya madm3chanic, I don't think he was meaning to be in your face, it's easy to misread internet posts.

Great to see yet another west aussie on here doing custom work. Make me a frame you talented bastard and we'll ride the goat track!

hahah i havnt heard anyone talk about the goat track in years, you've obviously been around the block a few times how about we dominate the eagle trail? god damn i have horrible memories of trying to keep up with fit bastards on that thing.

 

[Gregory]

lol, don't people ride that anymore? I suddenly feel old. I guess it a DH run anyway.

Eagle trail it is then

 

[Tench]

You have a PM, with a sneaky peaky pic of my new frame design 8)

Aren't you afraid that madm3chanic will return with a third design, much reminding to yours? 8)

It will be out there very soon for all to see. Maybe someone will see an aspect of it that inspires them in their own build, after all, imitation is flattery!

Madm3chanic certainly has the ability to build a very tidy chassis, I hope he focusses his talent with some brilliant inspiration too and brings more frame options the community. I was merely showing him that there are other design options that have not been explored yet as he mentioned that virtually everything had already been done. There are a few aspects of my design that I have not seen done on ebike frames.

Peters, your build is pretty amazing too, I love the swing arm! and you made your own BMS!! But I am with you there, the BMS used in many prebuilt packs has to be the weakest point on many of them and an area where a lot of improvements need to be found.

 

[0utrider]

i should probably post a few pics of some of my previous frames so you's know im not a dreamer

The dreamers are the doers that plan.

 

[0utrider]

basically im proposing a kind of open-source frame

This is an exciting prospect that you are willing to share the results of your design and implementation and enourage participation from others on the project.

Bravo!

 

[peters]

My comment above was intended to be a joke, I did not want to offend anyone
Thanks for your remarks on my frame madm3chanic and Tench, I'm also curious about your designs, and I want to follow them, that's why I'm commenting here.

It is really not easy to make a frame that looks good, works good, lightweigth, fits all batteries, etc...

 

[John Bozi]

just spotted this awesome build on fb.

https://www.facebook.com/photo.php?fbid=935263753155669&set=a.923717674310277.1073741827.100000161580553&type=1&theater

for those scared of the link here's one pic

 

[madm3chanic]

thats pretty cool build, super simple, quite light too. i gotta say tho i dont think that swingarm would be stiff enough if he intends it for an off road bike- if he intends it for on-road or just a commuter then it'll probably fine unless he starts cornering hard at 80km/hr.

 

[madm3chanic]

been a while since i posted any pics, iv been quietly working away at this in my spare moments. the concept is comin along nicely i think!

im trying to find 2" x 0.5" steel RHS to use for the main bearers of the front triangle but cant find it anywhere so this is modelled with two bits of 1"x 0.5" welded together; id much rather do it from one bit of wider profile tho. anyone know where you can get 2" x 0.5"? i know iv seen it in the past at a salvage yard i used to work in, no idea where it came from tho.

this frame is for the 40 series headway cells, so as shown its 22s2p (74.8v 30ah), thats a fark load of battery.

thats my first swingarm model, im not sure i like the aesthetics of it yet. i dunno about the round tubes with the predominantly square tubes of the front. i might change the chainstay profile to a rectangular tube this evening and see how that looks.