Chassis rigidity....

[TAftonomos]

Question for you engineering types out there.

There are a few options when going 2V into 999 frame.  A lot of people take the route I am, whereas you use the whole frame including the portion which extends down to the swingarm pivot/through the case.

There is another way, ala monster, where the swingarm simply pivots on the case itself, and does not tie into the frame at all directly (except through the engine case).

Is one significantly better than the other?  Mind tells me having the frame extend down around the swingarm pivot is better.  Then again, the case really shouldn't be flexing much at all....would it?


I'm asking, cause I could lop off another 5lbs of frame, get rid of the heavy linkage suspension setup in favor of a direct linkage ala SS.




This is for a planned second build.  Currently I'm using a hyper motor, which doesn't have the bearings in the case.  The next build would be to use a supersport motor w/bearings in the case.

[Langanobob]

I'm not a frame expert, but since no one has responded yet I'll post my opinion.  Maybe it will so deeply offend the guru's that they will have to respond.

If it were mine I think I'd save the 5 lbs and just use the engine case as a pivot.   Using the frame extension may provide some incremental extra rigidity that I think  will only be useful on a racebike.  And, as I recall from a few years ago, bikes with extreme rigidity were causing some handling issues and so designers started designing in a certain amount of flexibility.

The frame extension my provide some extra strength and protect the cases in a crash, but then I hope  that won't be needed.

[bikepilot]

I don't know about the strength, rigidity, but I would pause a bit before giving up the 999 rear suspension.  My guess is that the linkage setup of the 999 would function considerably better than the direct setup of the SS.  It also seems plausible that its actually not much, if any heavier ( haven't weighed it, but a couple of aluminum links might not be much more weight than the swingarm hoop).

[TAftonomos]

The link and pivot isn't what is the biggest chunk...it's the swingarm.  I will have weights soon, but the SS arm is a bunch lighter than the 999 SBK arm.  No linkage, lighter swingarm, no lower portion of the frame....I'd guess 8-10 lbs.

Again, it's in the future as the current motor I have has no case bearings, so I'm "stuck" with using a SBK arm.

[Speeddog]

You're asking 2 different questions.

The SBK setup is better, with the frame tied into the swingarm.
IMO, Ducati puts it on the SBK because it's better on the track.
Whether that 'better' can be detected in street riding... well, probably not.

You may end up saving some weight with an SS-style setup.
It can force some packaging compromises that push weight back on, but it depends what duty the bike is going to see.

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BTW, has anyone ridden a bike with the shock mount that's shown in your pic, copied and circled below:



'cause it makes my neck hair stand up....

[$Lindz$]

I don't think it will matter what you decide to do with the frame since you're taking away everything good about the 999 (engine and suspension).

[Düb Lüv]

You're asking 2 different questions.

The SBK setup is better, with the frame tied into the swingarm.
IMO, Ducati puts it on the SBK because it's better on the track.
Whether that 'better' can be detected in street riding... well, probably not.

You may end up saving some weight with an SS-style setup.
It can force some packaging compromises that push weight back on, but it depends what duty the bike is going to see.

-----------------------

BTW, has anyone ridden a bike with the shock mount that's shown in your pic, copied and circled below:



'cause it makes my neck hair stand up....

i've been talking to kaemna about making me a ss valve cover shock mount for a different engine. it's nearly done. they just had a hiccup with their cnc machine. it's a piece that has ran over a weekend.

[TAftonomos]

I don't think it will matter what you decide to do with the frame since you're taking away everything good about the 999 (engine and suspension).

Thanks!  I'll sell the entire project now and go jump off a cliff    Currently I stripped down a perfectly good 749R, and I'm using the entire roller from that piece of crap.  Don't let the church of ducati know about it, I'll be tossed out (if I'm still in?)


Not anyone I know Speeddog.  Kaemna claims they have raced said configuration for 3 years (iirc) with no issues.   I've already aquired enough pieces to do another one (a bit different), and I'm sorting out my options.  Shh...don't let Lintz know about it.

[$Lindz$]

I won't tell, you might be burned at the stake! Haha.

Nah, I didn't mean that in a dickhead kind of way... you know how the internet doesn't convey tone very accurately. But yeah, anyways, I would keep the 999 suspension! Haha.

[TAftonomos]

 


Goal is to build something really light.  I'm not quite ready to commit to a Ti frame, but I want it as light as I can get within reason.  2-3 lbs here and there add up....if I could wack 10lbs off on something as inexpensive (relative) as that.....

[Raux]

between kaemna and durbahn I would trust either one of their opinions.