Australian Streamliner Bike Build

[fastlammy]

Really nice Jon, was just wondering the other day how your going.

[Stainless1]

Jon, are you sure 18" is enough? 24 might be better... 30 might be best.... it is easier to haul a little extra air inside than not have room for something that might make it faster, safer or a little more comfortable for that 90 seconds of fun. 

[twodear]

Jon, your work is really impressive!

How much does that swing arm weigh? For sure it is strong but it looks heavy...at speed, how much do you think the inertia of it will reduce the amount of time the tyre is actually in contact with the salt? Is alloy an option rather than steel?

[wobblywalrus]

The critical weight issue is the weight of the swing arm in comparison to the unsprung weight it supports.  A heavier and well triangulated steel swing arm is not a big issue if it is supporting an elephantine mass.

[Dr Goggles]

Good work Kiddo,

love the renders, love the swingarm and the tank idea sounds all v good, tough work doin all that with hand tools or do you have electricity in Queensland now?

Jon, are you sure 18" is enough? 24 might be better... 30 might be best.... it is easier to haul a little extra air inside than not have room for something that might make it faster, safer or a little more comfortable for that 90 seconds of fun.  

Careful there Bob you'll get a lecture on wetted area if you're not careful, he's already added length without having too much of a sook about it, in fact he's dealt very well with the whole "joining the special construction club" thing overall, try not to give him the willies.

 

[Jon]

Thanks Guys

Stainless; Goggles is wrong, there was a lot of sooking before i admitted to needing a bit more room, I "need" about 6" for the scope creep the other foot is me already admitting defeat.
Contrary to popular opinion I think short is good for drag, more anoyed about having a parallel section  , lack of planning will do that to you.

Thanks Jim, CAD and Waterjet (with crappy photography skills) can make anyone look good, first time I've used it and seriosly happy with the outcome, had to touch up two pieces with a flap wheel to get the fit i wanted, that was a reflection on my drawing abilities rather than the waterjet operator.
Solidworks told me it would be 12kg with a bias of the weight towards the pivot end, i think its a fair bit lighter than that though, I'll weigh it tonight.
I'm more comfortable working with steel, it has a more predicable failure IMHO opinion too, if the salt Gremlins are kind and I ever get up to a decent pace i think that a lot of the suspension is in the tyre at speed.

Bo; I agree completely, I'm going to have a fair bit of unsprung weight anyway, talking with Greg (Maj on here) and he pointed out that i need to take brakes a bit more seriously, now looks like my rotor will weigh about 9kg.

Thanks Pops; I think we got electrickery thing happening up here now, I looked out the front of my place last night and the telephone ploes looked like they were glowing on top, donchuwuryabout that.
Went down to NSW to catch up with my brother recently and they have phones down there that arent plugged into the wall.
You been reading The Leading Edge again Goggles?

[grumm441]

Just don't put the gearshift too far away
G

[Jon]

Just don't put the gearshift too far away
G

You taking it for a run Grumm? Cool.
We're about the same height (I think) main shift is on the left thumb, underdrive to direct will probably be on the right.

[Jon]

Really nice Jon, was just wondering the other day how your going.

Thanks Nicholai
How is the collecting and test rig coming along?

jon

[Stainless1]

Jon, I would not worry too much about unsprung weight for a salt vehicle.  My scooter had a about a 160 lb swing arm after I added 68 lbs of lead to the inside and 60 lbs on the outside.  The tire stayed on the ground a lot better than it did with a 35 lb arm.  You are not building a canyon carving street bike, you are building a very fast race bike for a relatively flat surface.  Suspension reaction time can't possibly keep up after you exceed 150 or so.  That inertia thing works both ways, it takes a lot more bump to push a heavy arm than a light one.  You are going to have heavy springs and highly damped shocks behind all that weight... you don't want a compliant dirt bike suspension.
The Lakester has a lot of parallel surface.... seems to go OK... go ahead and give it the extra 6 now, it will be easier than in 6 more months. 

[Jon]

Thanks Stainless, not too concerned with unsprung weight, especialy after looking at successful sit on bikes, the sprung/unsprung ratio is pretty wild.

I cant put the extra 6" in now, i would be taking away the opportunity ofr you to say I told you so, (again) in 6 months time 
I think most peoples first post on my build diary was "add 2 metres", I'm a slow learner

jon

[maj]

Enough weight that the tire deflects rather than the suspension having to move should do it 

[Dr Goggles]

Suspension reaction time can't possibly keep up after you exceed 150 or so.

I've always had an intuitive feeling that I could never find enough hard evidence to back up so I've never jumped up and down much about this but it was the general idea that left us will no suspension........

Thanks Stainless, not too concerned with unsprung weight, especialy after looking at successful sit on bikes, the sprung/unsprung ratio is pretty wild.

I cant put the extra 6" in now, i would be taking away the opportunity ofr you to say I told you so, (again) in 6 months time 
I think most peoples first post on my build diary was "add 2 metres", I'm a slow learner

jon

that there is a successful application to the "Special Construction Club"

Just don't put the gearshift too far away
G

it was a morning sickness drug...

[grumm441]

Just don't put the gearshift too far away
G

You taking it for a run Grumm? Cool.
We're about the same height (I think) main shift is on the left thumb, underdrive to direct will probably be on the right.

Dave would have a better chance
G

[Jon]

Enough weight that the tire deflects rather than the suspension having to move should do it 

Yeh yeh; you have all the local tyre and battery shops on speed dial in case you need a quick fix.

Believe you and Stainless are right (both have runs on the board) at speed suspension is nearly all tyre flex.