PTT Laguna Seca 4/27

Got it mocked up and the part is in production. Worked out the factory dims and design features as best I could from photos and video I found. Their clamp is between 16-18 mm in thickness. I went with 19 mm for extra factor of safety. I didn’t go with chamfer at the front of the factory clamp because of the added cost to machine it, design simplicity, and safety. Threw it into some FEA software and there’s no significant stress concentration on torsion. It’ll be super strong under lateral loads because of the T-beam design. Will be machining it out of billet 6061 so there might be an added strength over the cast part (not sure what alloy is used but it’s probably A380).

bp_SFV4 said:

What's the total cost per unit?

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Price went up from my original quote due to changes in the design (a little more intricate with some countersunk reliefs) and asking for more accurate machining/tight tolerances for the forks and steerer. Cost for 1 part was $200. And this is for a pretty highly machined part. There’s a decent amount machine time. Cost goes down considerably with quantities ordered.

If you bought an aftermarket triple that’s not adjustable, you’re getting hosed. They’re probably producing them with a 50-70% margin

bp_SFV4 said:

Are you considering anodizing? Would that cause changes machining dimensions?

$200 for the machine time and stock required seems cheap.

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Not planning to anodize. It’s good to live in an area of lots of startups and innovation.

Also will be testing for cracks after its first use.

andyb said:

Seems a bit of an expensive uneducated cluster Fook to me that isn’t actually doing anything over the std part!

Personally I would pay for a reputable design and manufacture that has a purpose eg adjustable offset, over the back of a ... packet concoction !

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You do you. Have you seen any FEA of these "reputable design(s)?" By your logic, trust is determined by practical experience not what's written on the internet.

Picked up the new triple clamp. Seems like it’ll fit. Need to tap the threads. Will be using M6 bolts for the clamps which is a size smaller than the stock setup. The factory clamp uses M6 bolts. Will get it fitted in the next few days.

Will be gaining about a cm of bar height which I’m hoping will help raise my forearms so they don’t foul on the tank. A cm of rearset height made a considerable difference so I’d assume the same at the bars.

Thought I’d do a little more learning about part design. Over the last week, I’ve been reading up on FEA and structural analysis to get a very (very) basic understanding of how this stuff works and justify to myself that it’s in fact safe to put this thing on the bike. If any engineers (not injunearz, you know who you are) are out there, feel free to correct me.

I ran this design through some FEA software and the TLDR is that it’s plenty strong. Applying 500 Nm of torque (about 4x the torque that the V4 itself produces) through the various axes yielded fairly minor displacements especially along the Z-axis (0.6 mm) and Y-axis (4.6 mm). When you apply a moment more sane like 100 Nm the deflection at the forks is only 0.9 mm in the Y-axis. Even then, this part shouldn’t experience those kinds of forces.


This is the twist along the long axis “Danger Level” (aka inverse factor of safety) simulation at 500 Nm. You’d have to be in a very bad situation to put that much energy into the system. At something more realistic at say 20 Nm the FoS is like 5+ (3 is what automotive should be). Note the stress riser at the steerer clamp. Where I thought there would be weakness would’ve been at the fork clamps.


500 Nm along the front of the clamp (Z-axis).


This is the displacement along Y-axis at 100 Nm. Movement is exaggerated and not to scale.

The majority of the structural support comes from the bottom triple. The top triple clamp is basically isolated and locks the forks and steerer system. It doesn’t particularly need to be strong. In fact, some of them are down right plates as seen on the KTM GP bikes.

andyb said:

I would of put the clamps inboard rather than on the outside or at around 5 o'clock rather than 9.
plus it looks a bit bland.....

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Corse engineers seem to disagree. That would position the clamps at the weakest point… I guess that’s what you get when you rely on practical experience

spooky said:

Honestly, at the pace you are riding it probably doesn't matter in the least. If it actually makes a difference to ergonomics for you then great, but if I were you I'd probably buy a bike that fits you. A 250 would be awesome fun.

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Honestly, you can give me advice once you touch a knee to the ground

spooky said:

If you are backing it in and sliding the front while riding at 50-60%, I can’t imagine what’s going on when you put in lap times faster than mine. I’m not sliding anything and not sticking my knee out to get it down and yet not going any slower than you. Strange.

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It’s all about control. And the Honda does look great! But the V4 will do for now and I’ll just slowly dial in my ergonomics.

Don’t you find it kind of weird riding slicks in the novice group?

andyb said:

but corse engineers aint making a piece with the motivation of putting bar risers on....completely different animal....

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You don’t know what Corse engineers are thinking. You can barely think logically yourself.

And who said I was putting bar risers on? Plan to use the stock bars.

You might want to take a better look at the KTM triple. What you’re focusing on is the adjustable bar locating system. Ducati run a carbon plate over top.

spooky said:

Not at all. Where I ride the times you and me are doing don’t get into the fast group. Not even close. The fast guys are five seconds off the lap record. At Most that’s held by JR in WSBK.

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How do you like them apples. What YOU’re doing doesn’t get into the fast group.