@ Braindead, are you a mechanical engineer? You should be having plenty of patience to do that. Great work.

Where did the frame deflect by 0.5mm. I think it is a high value for static loading. Please consider loading also. I believe dynamic loading will bend the frame a lot more.

Also please try to place the horizontal tubes a little bit closer to each other. The longer the pipes hang, the more will be their bending freedom. You can also try adding one more horizontal tube above the engine. This will shorten the length of the cross tubes, and hopefully it will improve the frame's stiffness.

The bmw tourer(not the gs series,the bigger ones) has an interesting front end mated to a subframe.in your case you could try the same or beef up the stock RD downtubes to mount a similar setup.

Abhishek,wouldn't it be easier for you to adapt a bmw telelever front end?based on your requirements,i suggest you look up the K series suspension.I'm not a huge fan of their designs,owing to conventional reasons.

keerthy,
i get you are worried about the buckling of the tubing going around the side of the engine. but unfortunately, there is no space to put an additional transverse member. i am considering using ~40mm members for them but that may not be needed as the forces are carried away from them to the top transverse member.

the 0.5mm deflection i got was for static loading but consider this... that was a 20 Kn (approx 200kg) horizontal load on one point of the frame. and the whole length of the frame is no less than 1 meter. anyway, thats an old version of frame and i still have to do the analysis for the new one.

and no, i am not a mechanical engineer, i am an architect. i dont think it matters as i have done my bit of studying in this and surprisingly few mech guys i have come across know as much about their stuff.


and stinker,
the bmw telelever setup was among the first things considered.
the main reasons the setup was eliminated...
1. the rake and trail increases with suspension compression. this is the opposite of what we want.
2. i dont want to modify the rd frame for this as that would mean using the same rake angle which is 27 deg. i want the rake to be no more than 24 deg.
3. the way the loads are transfered, the stock headstock will end up being structurally redundant, and i cant sleep with that.
4. the system still uses telescopic sliders. under hard braking, the sliders still tend to stick and reduce effectiveness of the suspension... and hence grip.

the double wishbone layout i am using is way superior to the telelever layout. tho only reason bmw are sticking to it is because it looks similar to the telescopic fork, so its easier to sell.
i dont care for that. i need it to have the best performance possible... dosent matter if it scares a few traditionalists away.

cheers

@ all..no braindead isn't a mechanical engineer..he's an architecture student with a megadload of automotive quotient.. You need to be mad in the head to go this far with chassis development. Most so called talented "tuners" have nothing/very little to add to a discussion like this coz they are more than happy with the engine mods, and also coz it takes real brains to make a chassis out of scratch and get real time improvements on the track..its a pity it still hasn't caught up yet

that makes us pioneers then!

for some reason, i feel architecture is a good background for a motorhead to do something like this. you have trained yourself to be imaginative and practical at the same time.

most people are not aware of the handling deficiencies of their bikes because there are no tracks in india except 2 in tamil nadu. there is no culture of sweet handling bikes and too many people who say "look how great my bike is!" instead of "how can my bike be better?"

but i see a massive irreversible change, and that is good.

What you study or studied does not matter. It is the passion that really matters. You must be knowing of Joel's works. He is a software engineer. Many find it hard to believe that.

I know of an automobile Diploma holder, who can't tell the difference between a 4 t and a 2t engine. All i hear from him is blah blah blah. I know there are many many more like him.

@ Braindead, if i had a better computer, then may be i could help you on the frame design. Let me see if i can get my current calulator to work well.

latest update:

spent 18 man hours trying to simplify and lighten the joints for steering and ended up with a solution much more complex... that means a dead end.

i sound like a wise man i know!
but its true.

the current joint is a 'ball and socket' and Taper Roller bearing hybrid. the ball needs to be made in Stainless Steel, hence the weight. Tried to do away with the ball and tried going back to a floating headstock design but tried an insideout one this time. (the headstock being a thin tube sitting on the inside on the bearing, instead of a fat one sitting on the outside.)
two words... dosent work.

i am sure it can be made much simpler but that would mean using fancy casting systems or making a billet piece using complex cuts. both impractical.

so back to a ball joint. i am not very happy with it but its easier to do.

the funny thing is that you wont even be able to see the ball once assembled.
it is possible to incorporate a friction steering damper within the ball joint though.

working on the swingarm now.

Glued to this. Imagining the final result (which for sure will happen soon) is giving me goosebumps.. I only wish I could see it in person when it's done. Rest will remain stock on the bike? (sprocketing etc) Or is that stage - II?

What about the softwares on Tony Foale's website? The ones for motorcycle setup and front suspension I mean. I'm sure they would be a big help.

wanna see some pics of all the techy jargon going on here.. i understand dynamics, but by hand or visually, cant understand a damn thing if discussed in words...

there is a new detail or option happening every few hours now that i am done with the uni. its too much to post up. and frankly, much of the details are nonsense.
they are just for me to see if it can be done easily and if they work.

if i had been doing whats already been done, the whole thing would have been ready last month.

also, i hope you understand that i am putting in some serious time and mental muscle into this, so obviously i wont be putting up 'all' details on any open forum. but will try putting something up soon.

How hard is it to find them in India?
do any production cars use them?

i need (min 2, max 6) M 8 X 110 grade 5 studs with metric threads on 15mm from the ends.

anything similar will do. if there are similar size studs or even bolts available readily, i can redesign the part.
two of the studs have to take the entire front end load in shear, so i dont think even SS will do.

using the Ti studs will really simplify the joints.

cheers

new stuff!





it may seem like the same thing as the last frame i uploaded, but this one is all new. mostly in details. have spent like 2 weeks counting 0.5mm s on cad and redesigned the whole thing. this frame is narrower from the top and wider at the front to start with.

swingarm is mounted a bit conventionally because the moment i drew the chain in 3d, it was too much pain adding lightweight reinforcement to avoid twist. took me almost a whole day to figure the swingarm.
i am using the swingarm as a structural member in the frame and that concept has been carried over elsewhere on the bike.

the front geometry remains unchanged, but increased the stroke by negative 25mm to account for suspension sag.

the way both suspension units come together at the same point, a majority of the static weight of the bike bypasses the frame entirely. this means the frame itself comes into play only for dynamic loading, making it efficient.

had a funny moment today, took a tape measure out to show friends exactly how big the frame will be and the point where the suspensions meet is about 750mm above ground. thats as high as your bum. its really tiny. the best way to reduce weight is to reduce size.

Can you please post a side view of the frame? Want to see how the front end links with the rest of the bike. And, is this type of front end developed by you, or is the concept already there? And, what about the unsprung weight at the front? Will it cause any problem?

the type of front end itself is not new. its a Hossak / Britten type setup. the geometry of the linkages is my brain. the geometry ensures the front axle travels in a specific curve, giving control on the rake and trail depending on deflection. such control is not possible in telescopic forks, among other drawbacks.

the unsprung weight will be a bit more than the telescopic front. by how much, i have not calculated yet. i intend to offset the drawback by using fancy wheels.

also, the unsprung weight is just a part of the story. even id the telescopic forces have low unsprung weight, but they loose the advantage due to fork sticktion during braking. this setup continues its suspension operation at 100% effectiveness at full braking.
at the end of the day, this setup will allow the tyre to follow the the road better than telescopic forks.

on the same topic, did you guys know none of the indian bikes (except probably the r15) have a simple thing like metal guide bushes in the fork? they improve the quality of ride and roadholding under braking by a lot. and they have been in use all over the world for the past ~20 years! high time we wake up.

about the side view, i have mentioned the geometry of the suspension linkages as my brain's product. its never been done before. i dont think anyone thought of it in this way.
i am avoiding putting up a side view till i build this. sorry about that.

cheers

No prob about the side view. If you want someone else from copying your idea, its understandable.

About metal bushes, Bajaj advertised something similar in the XCD135 and newer bikes like P220 DTSi. Not too sure though.