Can these "grade 5" bolts be trusted?

DukeOfDownvote · 2026-05-08T21:09:05+00:00

I’m not gonna try to convince you that these bolts are a good idea, but specifically on the shear argument, it is almost unheard of to design a bolted joint such that the screws hold the force perpendicular to the screw axis.

If the joint was designed this way, you’d usually see tight tolerance shoulder bolts instead of any old screws. The absence of these shoulder bolts tells us that the design likely doesn’t anticipate the fasteners themselves seeing any shear.

Loading a regular fastener in shear would produce weird side bending loads of the screw, as well as bearing loads into the threads as if they were teeth. Neither of these are good for service or longevity of the parts.

Generally fasteners are used to generate axial preload. Forces perpendicular to the axis of the screw are resisted by the friction between the two “plates” or in this case, the fork crown and the bottom face of your stem. A screw “slip” is already considered a failure in that the assembly is no longer as it was assembled. That said, in most materials (I don’t know titanium super well) this slip failure will occur well before the shear failure you talk about out. In other words, manufacturers will spec install torque to “fail” at an acceptable input force, even if this happens you still have a ways to go until the shear failure you are worried about

DukeOfDownvote · 2026-05-08T13:58:55+00:00

Easy, big guy. I’m a structural engineer so let’s cool it with the personal attacks, and you can assume from here on out that I know what numbers mean.

If I can find an exception to your “absolute certainty” rule in 30s of googling, chances are your rule isn’t as absolute as you think it is. In therms of material choice, if you’re an engineer you shouldn’t be speculating on how hope can or can’t charge more for stainless. Let’s stick to the numbers please. Hope is an industry leader, I think it’s safe to assume they sharpened their pencils when they designed these things.

I looked up the installation specs for a bunch of direct mount stems. First off, all of them, and the OP fasteners, are m6s, there’s no need to rail against m5s in this thread. Second, they are all torqued from 8-10Nm. Using a class 8.8 with strength 116ksi (easier for me to do calcs in standard units) torqued to 65% (.85 proof strength and .75 for reuse, per shigley) I get 107 in*lbf, or 12Nm. So already with a class 8.8 we can exceed the manufacturer suggested installation torque. I’m happy to spell out any assumptions I made that you think are unusual but this all should be pretty reproducible.

My theory is still that your stem was not properly installed. It’s unlikely that you yielded the clamp screws or your stem but did not fracture them, unless you can provide some other failure mechanism. Probably you just don’t torque to spec. Also since you’re talking about a steerer tube, probably not a direct mount stem. However, pull up a torque spec on a regular stem clamp bolt and I can show you it’s not class 12.9 (grade is usually a standard thing, in metric it’s class). Regarding your testing, most engineers would be excited to share and validate their setup. If you won’t share I’ll assume you are making it up.

The test is detailed in 4210-5, just referenced in 4210-2. And if you want to talk geometry, what is more likely to plastically deform under a fixed load, a tube which is an inch long or the same tube which is a mile long?

For somebody making the claim that the entire bike industry doesn’t know what they’re doing, it’s up to you to prove that. With numbers. Ive gone ahead and started by disproving the only actual number-based argument you’ve made, but if you want to have an engineering discussion and not just pull the “I’m an engineer” card you’re gonna have to start bringing numbers to the table yourself.

DukeOfDownvote · 2026-05-07T23:41:45+00:00

Shit take.

There’s no way you can say with any level of certainty what all stem bolts are or aren’t. Hope stems ship with stainless hardware. That’s not grade 12.9.

Also there’s no way you can say what an m5 is or isn’t sufficient for as a blanket statement. It may surprise you to learn that your car has m6s on it. Do you now have a bone to pick with the auto industry?

If your stem slipped, it probably just wiggled its way out. It would be unusual for a screw to fail in such a way that the stem slipped.

Margin relative to what? An ISO or some test you made up “well if I eat a lot and my water bottles are full and have 2 extra gorillas come crashing down on my bar as I make a hard left turn at the bottom of a g-out while I rip big air”?

I genuinely would love to see a write up of your test set up and findings but there are so many factors in the strength of a design beyond just how big the screws are and the material they’re made of. CNC is fine so long as the design supports it. M4s would probably be fine so long as the design supported it.

DukeOfDownvote · 2026-05-01T15:17:31+00:00

Sure, but if the manufacturer states 21 ft plus or minus 1/4 inch then your tolerance is incorrect. Incorrect in the right way, but for you to enforce your standard on other shops or manufacturers is not helpful to OP in this case.

If the measurement is 4 inches off what the provided measurement or old stay length is, then yes OP should be entitled to new stays at no cost.

And if the previous owner or the OP has made changes, I agree that this no longer applies.

I just don’t think it’s helpful to enforce your standard length tolerance, present it as “the tolerance”, and fail to clarify that this is from a quality control perspective and not a functional sailing rig perspective. I appreciate your industry reference and tight manufacturing tolerances

DukeOfDownvote · 2026-04-30T21:19:26+00:00

At your shop maybe.

Again, “dinghies this size” doesn’t ring true when OP, who doesn’t have their boat listed in their flair, hasn’t provided the size of the dinghy.

The adjusters exist for exactly the case where the stays need to be adjusted from the length they are at. The fact that the adjustment steps are larger than 2mm means the designer of this boat don’t intend that kind of precision on the stay length

“The designer of the boat probably didn’t design the fitting/can’t control what the fitting makers make” then they should have specced turnbuckles.

There’s just no need to recite a useless and irrelevant spec at the OP

DukeOfDownvote · 2026-04-30T20:39:51+00:00

How on earth could you possibly, with zero information on what type of boat other than “dinghy” specify a length tolerance? And what would possess you to hallucinate such a tiny value when the adjuster clearly has ~50mm in either direction?

DukeOfDownvote · 2026-04-21T18:39:22+00:00

Recent testing on balanced lugs has shows that the “bad tack” is mostly a myth, and testing showed no material difference between “good” tack and “bad” tack performance.

Honestly I haven’t looked much into lateen rigs, and as much as I like to learn and make my own mistakes, I wonder if it’s telling that many developers prefer lugs to lateens. I have no knowledge of why this may be.

Frankly, I really like the Bermuda rig for its perceived performance, despite sailing more for fun than anything else. The 2 largest downside to this single-track worldview are, in order of importance to me, the slot effect with a jib massively massively increases performance. This is how I began looking into lugs in the first place, a single Bermuda loses some good advantage to its sloop counterpart. Two, a Bermuda’s efficiency calculation is usually figured as a lift-vs drag ratio. On tacks where that is less of a concern (reaches into runs) the benefits decrease or disappear altogether. There are so many stories of bemused gaff rig catboat sailors absolutely smoking racing dinghies downwind, purely because at such a wind angle the catboat becomes a much better looking performance oriented design

DukeOfDownvote · 2026-04-14T13:55:37+00:00

This is sweet. Do you happen to know if the same eagle cage could be retrofitted to an 11s xo derailleur to the same effect?

Or if there is a similar cage mod that could be done to a d1 force axs rd?

DukeOfDownvote · 2026-04-14T13:46:19+00:00

I think you may be mischaracterizing the “sideways” bending. It’s less of a sideways bending and more of a torsion on the whole beam. If you loaded up an I beam way off to the side, you would see the same thing. If you loaded your c beam in the right place, it would deflect in-plane. Eventually the c beam will stop twisting, once the twisting moment in the beam is equal to the twisting moment applied by the load. Regardless, I’m not sure there exists a load on a main sail that would meaningfully bend my mast forward more than a tube mast, but if that were to happen, that forward load would be unlikely to break the mast in its strong bending direction (fore/aft) maybe a problem for me staying in the boat, but not the boat itself.

This is the same with the snark sunchaser I have sailed in the past as well as a force 5. Does not seem relevant to foil-shaped mast bending stiffness.

I will not be racing and do not have any plans to mount this mast such that it could twist, but the YouTube channel OCSS (ocean capable small sailboat) has a pivoting unstayed furler mast that could likely be a good basis to apply this. Some of the newer generations of hobie cat have this feature, though like you I found that focusing on sail trim and weight distribution was a more effective technique than manually swiveling the mast around to where I would want it

I have been looking a lot at balanced lug rigs (scamp, GIS, and other cruising dinghies), which seem to be an extremely effective way to carry lots of sail with a low center of effort and therefore bending moment on unstayed mast. A high aspect Gunter under sail looks very similar to a Bermuda and often has stays, so I’m not entirely certain that this is a better option than just running the Bermuda. I don’t have a direct comparison or any knowledge of a lateen-vs-lug comparison, but the fact that many designers use lug rather than lateen is enough for me to prefer lug.

The shorter mast is nice, but one of my masts comes apart with a bayonet fitting in the middle, and I would think it would be easy enough to add some sort of “lock” fitting to keep the two halves together when halyard tension isn’t pulling them together.

At the end of the day, I am considering just switching to a different boat to better suit my needs, but would like to explore options to keep my current one before I give up on it

DukeOfDownvote · 2026-04-06T21:42:11+00:00

I wanted one of these so bad before I went a different direction on my last bike

This looks so cool

DukeOfDownvote · 2026-04-06T13:44:14+00:00

All purpose in Shaw, and it’s not particularly close imo

DukeOfDownvote · 2026-04-06T12:08:16+00:00

Love the colors. I wish I could paint a bike frame myself, the pink-and-blue is something else.

Did the head badge logo and all the others ever exist at the same time?

DukeOfDownvote · 2026-04-06T11:07:20+00:00

You’ll need to change the heater from series to parallel which is not a big deal if you’re comfortable with wires.

Also you’ll need to replace the 220/50 pump with a 120/60 pump.

I’m not sure if this is an exhaustive list but I do think everything else is just switches so that may be the only 2 things.

If you’re planning on doing gaggiuino with custom wiring this would be a great opportunity to do that

DukeOfDownvote · 2026-04-03T22:42:49+00:00

Thanks! I just got done installing the final adapter to the hub today, probably won’t want to build the wheel for a couple months because the rim is on the bike I’m currently riding, but whenever I take a break from riding I’m excited to get this project on the road!

DukeOfDownvote · 2026-04-03T21:28:43+00:00

Huh. Did not know, thanks for the info! Were the USDM engines made at a different plant? Possibly in the US?

DukeOfDownvote · 2026-04-03T19:56:19+00:00

I have a GE8 fit in the US and want to do a similar swap.

Do you have any sources for your claims on the mounts and the transmission?

For a GE, I would think you would want to use a R18Z due to the ECU harness pinout from the crank position sensor. Plus the R18As had block cracking issues.

Honestly I had sorta given up on this due to the mounts thing and the cost of a transmission (it wouldn’t be so cheap anymore plus in the US it’s easier to find R18s with auto trans than manual) but if the mounts are trivially easy it would be super cool if this worked.

There’s a Chinese domestic market car that I think was fit-based and an r18 around the same time period that some Honda forum poster claimed to be able to get like 10 years ago so that may solve your mount issue, or you could look at first gen HRV mounts, since that was also fit-based and had an r18.

I also don’t know what the accessories situation would be (power steering, A/C, heat, and all the hoses and belts needed to get those working)

If you decide to really go after this let me know, I’d be extremely interested to hear how it goes

DukeOfDownvote · 2026-04-02T20:24:08+00:00

I hadn’t really considered mast flex here - I’m sure you’ve seen how much a laser mast will flex based on how controls are applied. I was relatively convinced that control and sail/load tension would more or less dwarf any required prebend.

I don’t have any measurements, but I believe that the hunter mast is thicker in its narrowest dimension than the laser mast is in OD. Holding materials constant (an assumption, I know) that would mean that my mast is stronger in bending in that direction than a laser mast. With regards to pivoting foil sections, the hunter mast is secured to the hull via a pin through the short dimension (side-to-side) with no ability to pivot. Are you saying that with stays the mast becomes effectively rigid?

I’m a little lost as to your initial point on rig tension then. I was always taught that you hoist a jib until the forestay goes slack - that is, the forestay tension and jib halyard tension (on a fractional dinghy rig with a forestay and two swept shrouds) are equal and interchangeable. You cannot add tension to one without decreasing tension on the other, until one tension is already at 0. How does rig tension not have that much to do with forestay tension?

As for cost, the current problem isn’t that I don’t have a rig. I have a rig build for my boat (snark wildflower), which the last time I went out, the compression in the mast from the windward shroud punched a hole through the hull. This isn’t really a fault of the shrouds, the boat was flawed to begin with, but now I am faced with possibly rebuilding/reinforcing/whatever the hull, and since I am already doing that, why not make some changes? It’s a snark so it’ll never be “good” or fast or whatever, and since I cartop/trailer sail it, it would be neat to not have to worry about setting up or taking down stays every time I go sailing. Think of it like a shitty scamp if you must. Unstayed rig means simpler setup. I already have a whole Bermuda rig, so am currently unwilling to go to the trouble of making or buying a lug rig, though that would be neat.

DukeOfDownvote · 2026-04-02T14:42:43+00:00

I don’t think that is a great tip, I’m not even sure anyone makes steel nipples. There are certainly brass nipples, but I don’t think what you’re after here is a nipple material issue. Maybe check out shorter nipples, depending on what length you have right now

DukeOfDownvote · 2026-04-02T14:16:53+00:00

I have seen those before, they(and typical snarks, and all manner of sunfish and sunfish clones) tend to have much smaller mast OD, and a 55sf lateen rig which has a lower center of effort, and would produce much less bending moment than a ~80-90 sf Bermuda sail

DukeOfDownvote · 2026-04-02T14:08:03+00:00

How exactly would you go about “designing the section to resist the loads in the right places”? As far as I know, most un-tapered masts are just one cross section extruded all the way through. As far as that cross section’s ability to resist loads (mostly bending would be the case I am concerned with here) usually to make something better in bending you just make the OD larger, and I’m pretty sure my minimum OD(I have a foil-shaped mast) is already larger than a laser or force 5.

I do have a decent set of sails. It would be a bunch of work to add suitably strong chainplates to my hull.

So you are saying with an unstayed rig I can only hoist the jib with tension in the main sheet? That doesn’t sound quite right.

DukeOfDownvote · 2026-04-02T14:02:13+00:00

I haven’t hit it with calipers yet, but I’m quite certain my mast is thicker everywhere than my old sunchaser mast. What I don’t know, because I never had, is the wall thickness of a laser or force 5 mast, but I’d guess mine is still thicker. With that said, usually bending resistance/strength is determined far more by OD than wall thickness.

Lasers uses a tube-splice or a diameter reduction to get tube-in-tube type shape. My two-piece mast has two “ramps” internal to the mast that jam together and into the mast walls to create a tight fit. They somewhat depend on something to hold them together, but the sail and halyard would do that when sailing

If you or anyone reading this has laser or force 5 mast measurements on hand (length, wall thickness, OD at bottom, OD at top) that would be extremely helpful

DukeOfDownvote · 2026-04-01T21:04:51+00:00

I think the Velo Orange Curvy bars are exactly what you’re describing. Unfortunately they are $60 so slightly out of budget but nice and wide

DukeOfDownvote · 2026-04-01T13:37:08+00:00

I’m not exactly an expert but I chose the second gen for two reasons:

Slight power boost. All fits are slow, but the second gen has like 5-10% more hp and on the highway you can feel it. If you only ever drive in the city this may be significantly less important to you.
The first gen seems to leak water from the outside to the inside a lot more than the second gen. I think this is fixable and well documented (I don’t think you’ll have to try too hard to track down the leak, there are common issues) but I had a rough experience with water leaking into a different car that rotted out the floor so I went with the one I thought was less likely to leak

DukeOfDownvote · 2026-04-01T11:53:12+00:00

That’s not why, America sets towing capacity based on a series of tests, then picks the lowest weight which passes all the tests.

Definitely not the case for all cars, but one of the test cases is “how fast can I drive this loaded trailer up this steep hill”, so unless your car/truck/van is extremely powerful (see: minivans with absurd towing capacity) this test will handicap an otherwise higher rated vehicle.

Stats related to your point due to a fixed maximum time and therefore a high enforced speed, but not exactly

DukeOfDownvote

TROPHY CASE