Operation: Bazooka

[Hyena]

Hey guys,
With my previous favourite bike (norco dirt jumper) now gone (sold) it's time to start on my next build, and up the ante a bit

Here's what I have so far, after 2 big boxes of expensive stuff being delivered in the last few days I actually have pretty much everything to build the bike!

The frame is a Sintesi Bazooka which apparently has a pretty good name in the DH world. I was just on the lookout for a good full suspension frame and fellow Aussie ES member full throttle hooked me up with this one. Thanks mate!

The motor I'm going to use is a 9C 8x8 which falls somewhere between the 6x10 and common 9x7 windings. It has the most copper fill off all the 9C motors and an initial test on 15S lipo has shown it to be pretty good. Plenty of torque and it pops the front wheel off the line very easily with a jab of throttle. My old bike was running 18S lipo and had heaps of grunt, this one will be 20S (84v hot) and using a 100 amp controller so I reckon with over 10hp she'll go alright :wink:

The set up will be pretty much for off road use (I'm rebuilding my commuter bike to have both better suited to their dedicated purposes). The above pictured forks will go back on my commuter bike and my marzocchi bombers and 9" hayes stroker ace hydros will go on the bazooka. The back brakes will be 8" mechanical discs for now. I'd rather hydros all round but I'm not too fussed about the back brakes, they don't need to be strong anyway as the fronts do most of the work

The bike will be running a 24" sun double track rims front and rear - the front is already laced to a 20mm nukeproof hub. I have to get some custom spokes to lace the 9C. I wanted wider tyres but for now I'm running dmr moto diggers (24x2.35) Later I'll upgrade to halo Ception's which are 2.6" wide 8) Handlebars are moto style as picture above.

I can fit 15S2P lipo inside the frame but the remaining 5S2P doesn't quite fit. I'm not sure how I'll set it up yet, whether I make a wider section at the front and run the packs 2 wide or put 2 on the top of the top bar (as shown).

The first step will be to rub back and paint the frame. It's well used so has alot of chips and scratches.
I'm thinking satin black to match in with the black rims, forks, bars etc but am also toying with the idea of a dark camo colour scheme for the frame.

Stay tuned

 

[x88x]

Should be interesting. Yay for ridiculous amounts of power.

 

[liveforphysics]

8x8 is the educated man's 9c wind of choice.
Bike should scream.

 

[mud2005]

looks good so far, what brand are those handlebars? I like

 

[deVries]

8x8 is the educated man's 9c wind of choice.
Bike should scream.

Hi LfP, what would be the ideal controller & voltage for this 9c 8x8 wind?

Kool setup Hyena. 8)

Thanks!

 

[Hyena]

looks good so far, what brand are those handlebars? I like

They're 4130 cromo, made by Brave and the model name is 'Stiffee" :lol:
I got em on sale for $28 which is a bargain.
They also have them in pink, I'm thinking of shouting Aussie Jester a set

deVries, I tested this wind on my commuter bike with a 50 amp controller and 15S lipo (63v hot and around 60v running voltage on a full charge) At this current it had plenty of torque to pop the front wheel up off the line (a little more torque in a 26" rim than a 9x7 in a 24" rim) and while I haven't tested it by GPS yet the top speed is as fast as you can pedal with standard mtb gearing. I'm running a 14t rear and 48t chain ring and on the flat I was pedalling pretty fast to contribute to the motor (ie make the current drop) but with the speed it lost on hills I was able to pedal meaningfully in top gear to help it out. So yeah, if you don't want to use it as a motor bike and will actually pedal too the 8x8 on a standard 48v pack would go quite well with mtb gearing. As is always the story, if you want to go harder and/or faster you're going to need more current and more volts. And the key, more money!

 

[Hyena]

For those asking about the speed of the 8x8, 9C claim 48km/hr on 48v in a 26" rim and with a 75kg rider.
I just tested it under those conditions - 26" rim and 75kg rider and I have to report their claims are a little optimistic...

I just did a GPS run on 60v (running voltage not nominal) and clocked 46km/hr = 29 mph. So I reckon you could expect around 26mph on a fully charged 48v pack. I estimate it'll have a top speed of around 55 ks (35mph) with my 20S lipo pack. I rarely got my old bike over 60ks on the sort of rough surfaces and trails I ride and when I did it felt too fast so this new motor wind / voltage combo will be spot on. Anyone would think I planned it that way

 

[Lessss]

Their 48KM must have been all down hill.

 

[dogman dan]

Juicy! Love the way your batts will fit right into the frame.

8x8 9c sounds juicy. Who sells em? While I like the 6x10 in the dirt, 8x8 sounds perfect for a 48v close enough to legal street bike. For me, 48v on a 9x7 is just a tad fast, tempting me into riding faster than the speed limit on residential streets. But slowing down some at 36v is just too lame on the steep hills.

So the 8x8 sounds like the perfect compromise between the two, and if you want fast just volt up baby.

 

[Hyena]

8x8 9c sounds juicy. Who sells em?

I do

Well, not really. I bought a wholesale order of motors direct from 9C but I had to buy 50 in order to get them. Most were 9x7s but I got a few 8x8s too as they sounded great on paper for off road. I've kept 2 and a couple of Aussie members have the other few I ordered. I dont think your usual 9C sellers have them there and unfortunately shipping them from here to the northern end of the globe would be hugely expensive. If there's enough interest I could probably organise another group buy and have half the motors sent to the US. It'd have to be atleast a dozen though...

 

[dogman dan]

I figured that might be the deal. Too costly to send em to me from your house. But we'll be watching to see how yours does, and maybe a few certian vendors might start to carry them if there seems to be a demand.

 

[deVries]

I figured that might be the deal. Too costly to send em to me from your house. But we'll be watching to see how yours does, and maybe a few certian vendors might start to carry them if there seems to be a demand.

I'm sure Justin will add it to his next order. According to someone in China regarding DD motors it's very common to get a specific wind -it's not really even considered a custom/special deal. Even street-side retail vendors do these mods or specified winds "everywhere". Of course, with the benefit of millions of eBikes on the road...

 

[Hyena]

Look away AJ, the below pic contains duct tape

I've been playing around with battery mounting locations and decided I wanted to have everything inside the frame but keep it as open as possible (so the whole triangle isnt fully enclosed)
I came up with this - the packs are 2P wide but only about 80mm so not too wide to get in the way while pedalling (my old pack on the top bar was 100mm wide and my legs would just touch it while riding.

I just hope there's enough room for the suspension to move there and not hit the packs when at full travel. Full throttle, care to comment on how much movement the spring has in it, or how differently it'll sit once bolted to the swingarm ?
There's about 10mm clearance from the top of the spring to the bottom of the pack now

 

[SoMoney]

That isn't going to take the hits for long. The shock/spring will arc upward 1/4-1/2inch while compressing. You can try putting some crayon on the spring and jump off some curbs to see if any of the wax rubs off on your lipo. Tape loosens up with heat so what didn't sag and rub last week could start the next. Rub a lipo long enough and it will pop in a violent way...

 

[Garrick_s]

What SoMoney said.
You're gonna hit at some point.
what if your front battery is at an angle following the bottom tube and that may allow your middle battery to scoot up a bit and that may allow this....

Its that second battery right above the spring.
Your batteries running up against the seat tube should be fine.

just throwing it out there.
you probably have tried it.

nice start.

 

[x88x]

Looking at the picture, I don't think there would be enough space to shift them forward even with one along the diagonal. What if you make the front pair 4 wide? It'll stick out of the frame, but it should bring it far enough forward that your legs might not hit it?

 

[Hyena]

So money I wasn't planning to just tape them to the frame, it'll have a thin metal or perspex box around it for protection from knocks and water. But yeah I might have to wait until I build the frame up and get the swing arm mounted and assess the travel before I invest too much time in battery housings. There is a little more room than it looks in that picture though. The battery against the seat tube has sagged down a little under it's own weight with the minimal duct tape I had on it. When lifted up there's nearly an inch clearance from the spring. The reservior is still hard up against one edge but that could be rotated 180 degrees to give move room there.

My original plan was to cut out the top tube and replace it with a fat rectangular section that housed the batteries internally but I couldn't bring myself to hack it up after full throttle told me this frame cost 5 grand new!
I may still do this though - I'll build the bike up and see how it rides with the batteries strapped on any which way and if it looks like it'll be worth the hassle I'll start heavily modding the frame.
I'll have to see how it performs on 20S. If I dropped down to 18S I could do it easily but those extra 2 packs are slightly problematic...

 

[SoMoney]

With 1" clearance I think you just might make the arc. A metal plate protecting the cells would be smart....

22v packs are pretty beefy for four across.
Maybe use the frame

 

[Dingo2024]

Hyena, you can take the guess work out of this by removing the spring from the shock and bolting it back on (not sure how much of a pain that would be) . Slowly push the back end of the bike down with your hand and look at the clearance on full compression :wink:

Ian

 

[Hyena]

Yeah Ian thats what I'll do once I have the frame rubbed back and painted.
SoMoney those layouts would work ok with a thin framed bike but this one is pretty chucky already and would be very bulky with the packs strapped to the outside. I think if I can't fit them all inside the frame I'll put 2 along the top bar and the front. That'll still leave me room for a low standover height and not be in the way.

 

[keyne]

What are you going to do for a BMS?

 

[Hyena]

BMS's are for noobs
Nah I'll just use some sort of basic cell level LVC.
I very rarely take my packs to their rated capacity though so they never go near LVC. These packs are stupidly well behaved, my old pack which has been used nearly daily for over a year now has only been balanced about twice during that period, and even then it was only because I was being anal about a delta V of 0.08v.
I'm convinced having my packs soldered in parallel at the cell level and charging the 5S packs in parallel contributes to their good behavior.

That said I've just checked all 8 packs and 2 were suspect. 1 had a cell that was .15v lower than the others but it's come good after a balance charge. The second pack hasnt fared too well and has a 1 cell that won't go about 3.9v while all the others are sittinng at 4.2v. I'm discharging all the cells to 3.9v and will charge it again and see how it goes. If it doesnt come good I'll put it in as a warranty claim. This will be my first dealing with HK Australia so it'll be interesting to see how they behave. Their warehouse is supposedly at Taren Point which is only 10 mins down the road from my house so if they'll allow I'll just walk it in there and see if they swap it over. If not it'll only be a local postage issue to return hopefully.

 

[Hyena]

No real progress unfortunately, I'm still settling into my new house and building benches etc for my new workshop.
I did manage to sort out that low cell though, discharging all the others and slowingly charging it back up has them all sitting at 4.19v now so fingers crossed it's OK. I'll keep a close eye on it though, I suspect it'll be come a weak link.

Speaking of which, GOT LIPO ?

(blatent advertising in the background :lol

Anyone got some 300v rated fets ? I'll throw together a 60S2P pack for shits and giggles :lol:

 

[GCinDC]

Gorgeous bike! Nice!

 

[Hyena]

Slight progress. I swapped the 9" rotor over to the new 24" rim, mounted up the tyre and test fitted it to the fork to see how it'll look. 24" rim with 9" brakes *Tim the tool man grunt*
I'll be destickering the rims but haven't gotten around to it yet. I have destickered the forks though, not that I minded them but they were a bit hacked up. I might replace them with a new set to cover up the few scuff marks at the bottom of the lowers or maybe I'll just leave them all black.

Its xmas day here tomorrow so I don't forsee getting much work done then but hopefully the next day patch up the frame and rub it back for painting. I've decided to make it all black 8)

I'm still torn on the battery mounting options, I'll talk to timma in the new year about chopping out the top bar and welding in a T shaped piece in its place. I've dummy fitted all 8 packs and they'd go well if I do it like pictured below. The first 2 packs at the headtube end would be 2 high, single file to keep the width to a minimum to allow maximum turning with the triple clamp forks. Then the rest would be 2 packs long, 2 wide at the top with a single one underneath in the middle - making for a T or triangular sort of shaped top bar, which will be fine for pedalling with (85mm wide top bar), encase the entire pack with plenty of room for suspension travel and hopefully not stick out like dogs balls as being a big fat battery pack welded in there.



(excuse the crappy camera phone pic)