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First off, no, the bore should be a perfect cylinder all the way down. That said, nothing is perfect in reality, and there's a relatively large permissible variance from perfect that works just fine in this situation. The closer the better, obviously, but when you get the the point of "good enough", any better doesn't yield any returns. The mating surface (fork tube) isn't perfect either. I've measured plenty of brand new ones that were egg shaped by more than 0.05mm!
So what's going on with your clamp bore? There's a few things that can contribute to what you're seeing, it's likely one (or a few of) these:
1) You're assuming that the hone creates a perfect cylinder and that the clamp was the problem. However, the hone may be the problem instead.
a) How you honed them and what you honed them with will make a difference. Did you stick a hone in a hand drill and go to it, or did you set up the clamps on a mill and hone them with that? The latter helps ensure everything is aligned (primarily that the hone is parallel to the axis of the bore). If you're out of parallel, then the hone will hit the top and bottom edges more than the middle. Many hones are designed to accommodate an out of alignment situation, but those work best in long cylinders with the length much longer than the diameter (not the case here).
2) Perhaps the clamp bores weren't very cylindrical to begin with.
a) How the clamps were originally made makes a difference. Was the bore machined when the clamp was one solid block, then everything else machined? Or did they take a final finish cut on the bores at the end of the machining setup? The latter will yield a better result as the material has residual stresses from being extruded/rolled. As the part is cut out, the residual stresses cause warping, which would cause things to be misaligned somewhat. It's not massive, but it's there.
b) How was the bore originally created? Was it interpolated with a garbage endmill? Interpolated with a large diameter, high quality endmill? Or actually done with a boring tool? Was the machine new and high quality, or a worn out sloppy machine? Each difference will yield different results in the quality of the finished cylinder.
3) Perhaps the clamp bores were distorted in use?
a) How were the clamps you have used (assuming they're used)? Did someone torque the crap out of the pinch bolts? Did they go through a big crash? Anything else weird that could cause the middle section of the bore to pull away from the tube?
Regardless of what's happened in the past, all that matters now is whether or not the bores are in good enough shape to be used. For a non-perfect cylinder, the kind of non-perfect you're showing is on the better side of things. The middle of the bore doesn't do much of anything anyway. The bore aligned with the pinch bolts is what matters most, and those look to be high-spots vs the center of the bore (it would be bad if this were reversed!).
It's also good that it looks to be round and no egg shaped, but that's hard to tell for sure without measuring. If you have a good bore gauge, or a telescoping gauge and a micrometer, you can sort this out on your own. Be careful that things aren't artificially egg shaped - a perfect cylinder can appear egg shaped after the slot is cut (to allow it to clamp). Residual stresses at work here again, but once it's clamped on the fork tube that all doesn't matter.
The diameter matters. Did you remove a lot or material honing the bore? Was it appropriately sized to begin with? WP tubes are usually nominal sized metric numbers, like 54mm as opposed to KYB (53.85mm), so measure it up and see what it looks like. If it's off 0.05mm, it's not a huge deal. If it's off 0.25 mm, then it is.
Traditional anodize will indeed add to the surface, reducing the diameter. But they'll need to strip it first (or maybe someone did already). That will remove material to some extent, depending on how aggressive they strip it. If they're slow and careful, then re-anodizing it after stripping will yield a hole the same size as the originally anodized hole (likely a touch larger). If they aggressively strip, then re-anodize, it can remove a lot of material and look like crap in the end. You can also strip, electropolish, and then anodize, which will negate any build up of the anodize.
If it were me, I'd measure up the bores to make sure they're not way off. Then have the anodizer slow strip the clamps. Get them back at this point and clean things up with scotchbright pads, etc. to make it all look good. Then re-anodize in whatever color you prefer. A bare aluminum clamp bore is better at not slipping on the tubes during use (vs. an anodized bore), so if you really want to go nuts, have them mask the bore during anodize so it's not coated.
Finally, I've had shit luck with the lottery every time I've played, so no help there. Hope the rest was useful, though!
I used a 3-stone hone, not the flex hone types. I knew the finish would be rough but that is not hard to correct, as long as I used something that (in theory) contacts the material uniformly. IOW no hand sanding our Scotch-brighting. It is also not as rough as it looks in the pic.
I really should get a dial gauge and see if the bores are the same diameter.
They are out for anodizing ATM. I can still clean up the surface afterwards, or chuck it.
BP
JIC it was not clear, the existing cast clamps on the bike are fine. I am doing all this because I want to try running less offset / more trail. The only options for that are various used clamps from past years.
Replies:
Confirmed they should be a perfect cylinder, but are often not. I would guess that is where a very high quality clamp manufacturer like Luxon offers a huge advantage over OEM.
1. Understand the hone may be the problem. Clamped them in a vise and went to it. Used a drill, tried to hold at a 90 degree angle but was not perfect. Tried to only use the middle section of the hone by the pivots, moving back and forth only a small amount.
2. They are supposed to be machined billet (some KTM clamps are cast then machined to look like billet). Would not be surprised at all if they were poorly made. In that era KTM was not as organized as the Japanese brands. This is my third set of these and quality is known to be all over the map.
3. They are used and I do not know the history. Checked them visually and with various straight edges but that doesn't tell much.
Ran the hone VERY LITTLE and was trying not to remove material, only to see contact from the stones. Maybe 20 seconds per bore max (I should have done it wet). Did not slip them over fork tubes yet.
Did not think at all about the stripping process removing material nor the anodizing making them more likely to slip. Thanks.
I am gonna try and pull them back from the anodizer for checking and cleanup. Will update later.
Thanks again x1000 for the technical reply. It is great to have your level of expertise on these forums.
BP
A bore the wrong diameter or out of round will still work, it will just distort the fork tube more when it's clamped down (and cause more bushing binding). It also may take more torque to achieve the same clamping force as a more perfect bore, which will also distort the fork tube more. It's worth noting that this distortion is much less of an issue on the upper clamp than the lower since the distortion of the upper part of the fork tube is irrelevant (bushings don't pass through there) and it's also better supported by the fork cap.
The Shop
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It's very difficult to find any mention of these online anywhere - does anyone have a source for angled bearing races for a YZF? Looking to relax the steering angle a bit to help with its leaning character. Common item for mountain bike headsets, but pretty much a ghost story for moto frames.
The clamps guys will be in no hurry to offer these. Cheap brg vs 1k t-clamps. Guessing the tooling costs likely don't help......that and most people are clueless on bike set up. (including myself)
Rake and trail are two different things. The clamps offered are not changing rake like an eccentric bearing would.
You could actually change the offset only by using offset races. Could only get about 1mm of offset, unless you changed to a smaller O.D. bearing. Of course it would be challenging to properly install an offset race without index marks on the steering tube.
Expanding on what MX317 said...
I could be unaware of some frames and products, but as far as I know the mountain bike eccentric inserts for the headset are simply translating the steering axis toward the front or back of the bike to change the "reach" or "effective top tube length" and the wheelbase, but the total axle offset remains the same without a fork stanchion or "crown" (triple clamp) offset change. That means rake and trail remain the same on those bicycles.
These factory teams that are changing steering bearings and races are actually rotating the steering axis, to change the rake angle of the steering stem.
After market triple clamps in motocross only change the offset of the front axle by moving the fork tubes nearer or farther (translation) from the steering stem axis. Rake remains the same with a clamp offset change, but trail and wheelbase change.
Hypothetically you can manufacture a set of triple clamps that change the fork tube angle, but that is not the same as changing the rake angle (angle of the steering axis). A large change in fork tube angle would change the way the fork handles bumps when on vs off the brakes as well as how tube/slider friction comes into play in suspension action.
arent HRC using talon split clamps now (as per keefer review)
I'm looking specifically for an angular adjustment, not a linear offset.
First I'd like to say thank you for explaining things. I read a story where the mechanics made a very small change to something and didn't tell the test rider. The rider went out out several times and came back saying I don't know what it is but this one really feels different. So while I believe there are many changing variables, moisture content in the dirt, tire pressure, I also believe that some riders (a very small # of elite riders) do "feel" things rather than psychological.
TM
there's also plenty of stories of mechanics changing nothing, and the rider saying the bike is so much better now
There is that.
Certainly there are things that can be changed that can also be felt. I mean, that's a big part of our triple clamp business! And some riders are way more sensitive than others and can feel small changes. I'm not arguing that at all.
But there is a ton of nonsense in this industry that's commonly passed off as fact. Changing torque specs to change "feel", a "floating" rear axle is better than a "fixed" rear axle, and that titanium is more rigid than steel all come to mind...
And the phycological effect is VERY real. We were testing some triple clamps last year and there was a miscommunication with the mechanics as to which configurations I wanted tested (I wasn't there). They ended up testing two identical clamp setups, but thought they were testing two different ones. And the test rider knew that. The rider noticed a significant difference between the two identical clamps... Said rider is also regarded as an exceptional tester and is very accomplished. He simply felt a difference because he was expecting to, not because there was any actual difference.
That's where the engineer's job gets complicated. We have to run the feedback through our filter; knowing what we expected the results to be, knowing what our assumptions and unknowns are, knowing the limitations of our knowledge, etc. And then make appropriate design changes to make things better. This is where most all test riders fall short. They don't have the engineering background to tell the whole story, which is why the above nonsense is perpetuated...
And just to be very clear, I'm not dismissing the job of the test riders. They're critical to improving products. I don't want this turning into yet another post where people think I'm pitting engineers against test riders! That's not my point at all.
i've always thought it would be awesome if a magazine did a "test the testers"
make small changes one at a time and get feedback. Change the tire pressure, adjust the clickers, drop the forks, change the sag, etc. See who can correctly identify the change, or at minimum explain what feels different to them.
Ok I’m here to turn this thread into one of those… haha I’m kidding. I have come up with a new theory for you as I usually find myself at polar opposites of your opinion when it comes to these things so I took a step back and thought about it from another perspective. Much to the detriment of my racing results at times over the years I am one of those riders that are super sensitive to bike setup and always have been even when I was young and had no clue what anything was or did. I’ve cycled through more than a couple of suspension tuners that would just do the standard revalve and call me fussy when I would pick it apart yet when I find a setting that works with the bike I barely touch a clicker. I believe you when you say a titanium bolt is the same stiffness as steel or a cast axle lug is the same strength and flex as a billet one, so what is the feeling difference then? Of course these parts aren’t flexing enough to feel BUT they are transferring energy! I think fundamentally the terms for testing are wrong, soft stiff flex aren’t really explaining what goes on. A bike is a balance of transferring energy with a rider holding on and wielding it so materials either absorb, speed up or slow down energy travelling to the rider. The ktm axle mod adds one more part to the wheel assembly either slowing down or absorbing a part of the energy transfer from the back wheel “feeling” softer when as you’ve said these parts can’t flex. The light bulb moment for me was a max vohland interview where he said he had added a steering stabiliser to his ktm to slow down the rear of the bike subtly so his brain could process what was happening in time and not to calm down the steering which one would expect. Apologies for the novel but I’ve been dwelling on this for a while. The different manufacturers chassis designs fit into my theory as well if you want to delve deeper.
First off, everything flexes. Everything. There's nothing infinitely rigid on the bike. So when you change something, it may have a different flex, and therefore a different feel. I'm not debating that whatsoever.
The key here, though, is what is that difference in that flex? Did the part that was replaced have a significantly deferent stiffness than the new part (either stiffer or more flexy)? If so, then it's reasonable that someone may be able to feel that difference. But what if the part that was replaced has essentially identical stiffness to the new part? Should you be able to feel a difference if the stiffness hasn't changed? What if it's changed only 1%? What about 0.1%? 0.00001%? At some point the stiffness change is irrelevant and no one will be able to tell the difference. Such is the case with cast vs. billet axle lugs (unless they're an absurdly different design).
A key thing here also is that stiffness is directional. Alex Martin didn't want to ride with a billet linkage arm because it is "stiffer" than the stock cast one. Cast aluminum often has a higher stiffness than billet (it depends on the alloy) or the same. And if the geometric cross section doesn't hardly change, then the stiffness will hardly change either. We're talking total about levels of flex in this part that are measured in microns. And the difference in flex between the two linkage arms is dramatically less. The biggest thing here is that the direction of this flex is in the same direction as the shock motion; something with 300+ mm of "flex" (rear wheel travel). So the overall stiffness of the suspension has maybe changed 0.001% or less. Is it reasonable to believe he can feel that difference? Or does he just go into it "knowing" that cast has a different stiffness than billet? The tire is flexing 1000s of times more than that linkage arm. If the tire pressure changes 0.1 psi, it will make a dramatically larger change in feel than the change in flex between the two linkage arms. Have you ever measured your tire pressure cold and then after a moto? It can increase 2 psi pretty easily.
Titanium is about half the material stiffness of steel. And if the part hasn't changed geometry, which is typically the case with a bolt or axle, then the resulting stiffness of the part will be about half of what it was if it's made from titanium instead of steel. Yet many test riders keep saying that titanium makes a bike feel more rigid. Why?
And in most cases, the stiffness of a bolt is irrelevant if it's doing its job (holding the parts together). Such is the case with engine mount bolts. So long as the bolt's preload is enough to keep the mount from moving relative to the chassis or engine, then it doesn't matter whether that bolt is made from steel, titanium, aluminum, or sharp cheddar. It's simply along for the ride. Yet we hear of people changing bolts or bolt torque all the time for a different feel. It's just not possible. You can read a lot more about the bolt torque part here: https://www.luxonmx.com/blog-luxon-bolt-torque-tension.html
To your point of energy transfer, if two parts are the same stiffness, then only change in feel possible will be if the material damping has changed between the two parts. If you're replacing an aluminum part with a carbon fiber part, then there may be a change in feel as the damping between the two materials may be significant. But the difference in material damping between steel and titanium is minimal. Most engineering texts just lump all metallic materials into a single group as "metals" as the material damping just doesn't change much between them. If the stiffness and damping haven't changed between two parts, then it's difficult to see how any "feel" can be different.
The KTM axle adding another part is irrelevant once you torque down that axle nut. It's effectively locked together as one part, not floating at all. It is true that damping of an assembly increases as you add more components, but that's when you're going from a single component to lots of components. Just adding one that's effectively tied to the rest on them won't change much of anything.
Again, there are many parts on the bike that can be changed and do make a difference. For some parts it's arguable that only sensitive riders will be able to notice a change. But there are also lot of parts and/or changes that make no difference whatsoever, regardless of how sensitive the rider is. It's important to understand which those are in order to better your tuning and bike setup.
Pit Row
Yes, there needs to be some blind testing to verify these people can actually feel what they believe they can feel. The testers need to be Vital practice track warriors that drop serious coin on parts that they believe improve flex, bolt torque values, etc. Of course, no magazine will do such a thing because the entire "industry" and sales of aftermarket parts is largely reliant on the continuation of myths and folklore about flex and compliance.
I think your missing my point by being fixated on an individual part and not how it reacts in balance with the rest of the machine under load. Why does titanium “feel” different then? You haven’t given an answer or a theory because your textbook has said there shouldn’t be a difference? Placebo effect and predetermined biases work both ways…
Re-read my explanation of the linkage arm; the whole point is that changing that part doesn't change anything because it's an incredibly small part of the whole package. Everything we do is based on a single part's contribution to the rest of the machine, as that's all that matters in the end. The entire motorcycle can be thought of as a black box connecting wheels, footpegs, seat, and handlebars together. Those are the input points of load and your touch points to feel things. Everything in-between contributes to that feel. Understanding each individual part's contribution (or lack thereof) to that feel based on the force input is key.
To directly answer your question about why you feel a difference in that titanium bolt vs steel, you don't. You just think you do. Why? Because you made that change and knew you did it. So you expected to feel a difference. Or a test rider told you there was a difference based on their expectations. It's the same reason why they "feel" a difference with different torque specs. Reference my story about testing identical triple clamps above. This isn't to call you dumb or a bad rider or anything, just that the mind is easily swayed from reality by expectations of change.
I have read through all of your anecdotes of testing with b level teams with riders who are notoriously bad at setting up there bikes so it doesn’t really add any weight to your opinion. Why have torque specs at all then? There is a very broad range of torque between my engine hangers not falling off mid moto and me snapping the bolts off or how about if I tighten my swing arm pivot bolt as tight as I can it restricts the movement of the swing arm? But to be honest if a black box connecting wheels pegs and handlebars is your analogy for what a motocross bike is I won’t bother engaging anymore, ignorance is the biggest swayer of reality
Bolt tension and bolt stiffness are two different things. Material properties are a known entity, the engineers at SpaceX do not take what they "feel" into consideration when designing a bolted joint, they take material properties into account. When you tighten the head bolts down on your four stroke, there is a reason why the manual tells you to tighten to a nominal torque (to take slack out of the joint), then turn a certain degree of rotation. This is because the material properties of that bolt material are known, and based on the amount of stretch (induced by the rotation angle and thread pitch), the tension in the joint in now known to a relatively close degree of accuracy. There is no magic or guessing here, we design bolted joints this way for a reason and it's not because a scientist decided years before that he/she could "feel" a difference that was undetectable. You're basically putting hundreds of years of accepted practice out the window because you want to believe what a test rider is telling you, without vetting that information in any way.
If you actually ready Billy's analogy you would understand what he's saying, there are a set number of inputs to a machine and those are the contact points with the rider and the ground. When you introduce a load or disruption to one or multiple points of input, everything within that black box is contributing to the output felt at the other points, but to vastly varying degrees.
Because two pieces of metal or material are the same size, shape and material spec adds up well on paper......except for no two pieces of metal or casting are the same. And do i think a Pro level rider can tell the difference......yes, all day. You're both right to a degree. But one has a propeller on his head - the other is on his ass. U think MX is wacky - dem Moto GP guys be feeling thick paint
Well thankfully we’re not riding rockets! By your own admission the material properties are known for stretch and tension? Therefore by reducing tension and stretch on a bolt you are effecting a change? I have no argument with 100 years of engineering my argument is with the vitalmx eNgInEeRs that come on here giving ridiculous blanket statements shitting on an entire industry in regards of what everyone can and cannot feel or how small changes can or cannot effect a bike? A change is a change no matter how small so to decide what people can feel is just an opinion not fact
No, again you're confusing tension with stiffness. If I were to loosen the head bolt in question by 15 degrees, the stiffness of the bolt itself does not change, only the amount of clamping force induced by the deformation of the bolt does. As long as the joint remains rigid (which it will as long as sufficient tension is still present), then there is no change in the stiffness of the joint. Now, generally we want to keep fasteners like that tightened close to their yield point for material fatigue reasons, but that's a whole other discussion.
No confusion, you explained it quite well in your previous post. I never mentioned bolt stiffness we are talking about lowering the tension by lowering the torque spec effecting a change so you’ve answered it for yourself.
I can't remember who it was from PC, may have been on Pulp, but mentioned doing a blind swap from Ti to regular steel clamp bolts and every single rider liking steel bolts better without knowing what the change was, after complaining about suspension settings.
That's impossible
Triple clamp bolts are something special. If there's too much bolt tension, then the tubes get distorted, which binds up the front fork and makes it harsh.
If they switched from dry steel bolts to titanium bolts with anti-seize, but didn't adjust the torque to account for the lubricity of the anti-seize, then the forks will bind up with the Ti bolts. This would give the impression that titanium bolts are more rigid, but that's not what's really happening at all. They'd get the same result using steel bolts with anti-seize.
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