Ask the experts

[frorider]

^ as in Stanchion - lowers alignment. Yes the vids are interesting, esp since he points out this has nothing to do with burnishing the bushings.

[Wes Mantooth]

Is sudden brake failure a good sign a bleed needs to happen or should I be looking elsewhere? First time it’s happened to me on my dominions, but a long steep fast descent yesterday left my rear brake with zero power and the lever pulling straight into the grip for a couple mins until it cooled off

My understanding of this is that small amounts of water get into the system over time and mix with the dot fluid. When the water pockets hit a boiling point they compress and the system loses all power. Presumably putting fresh fluid in would decrease the water content and mitigate the issue? Or is this a sign of a leak etc

And yes I understand proper braking technique to mitigate heat buildup - been using these for years on large descents and bike park days and never had an issue before

[jdadour]

Diaz Suspension Design has a pretty good series of IG posts going about fork alignment rn. He shows before and after videos and talks about where they find issues. Spoiler: He doesn’t describe exactly what he does to fix things, because that’s how he pays the rent.
It’s the most recent 4 posts on his profile.


Sent from my iPhone using TGR Forums

I saw those too, and am very interested. Does anyone know more about what he is doing?

[joetron]

Is sudden brake failure a good sign a bleed needs to happen or should I be looking elsewhere? First time it’s happened to me on my dominions, but a long steep fast descent yesterday left my rear brake with zero power and the lever pulling straight into the grip for a couple mins until it cooled off

My understanding of this is that small amounts of water get into the system over time and mix with the dot fluid. When the water pockets hit a boiling point they compress and the system loses all power. Presumably putting fresh fluid in would decrease the water content and mitigate the issue? Or is this a sign of a leak etc

And yes I understand proper braking technique to mitigate heat buildup - been using these for years on large descents and bike park days and never had an issue before

Yes. First thing to do would be a full bleed of the system and replacement/flush of the old fluid. DOT fluid does absorb water and also breaks down over time with the heat and pressure of the braking system. Brake fluid should be replaced at least once a year if you’re riding regularly, especially in the park and with big mtn descents.
It’s a good time to check pad and rotor wear, replace as needed.
Unless you had a big wreck recently that might have damaged the lever or caliper, it’s likely not a leak, but I’ve had one Dominion lever leak from the seam of the bladder cap.


Sent from my iPhone using TGR Forums

[Wes Mantooth]

Yes. First thing to do would be a full bleed of the system and replacement/flush of the old fluid. DOT fluid does absorb water and also breaks down over time with the heat and pressure of the braking system. Brake fluid should be replaced at least once a year if you’re riding regularly, especially in the park and with big mtn descents.
It’s a good time to check pad and rotor wear, replace as needed.
Unless you had a big wreck recently that might have damaged the lever or caliper, it’s likely not a leak, but I’ve had one Dominion lever leak from the seam of the bladder cap.


Sent from my iPhone using TGR Forums

Cool thanks. I do bleed annually, but been riding 7 days a week recently so may need a sooner interval. Just checked/changed pads and checked rotors, cleaned calipers etc so figure it’s likely just faster than usual wear on the dot fluid

[toast2266]

Cool thanks. I do bleed annually, but been riding 7 days a week recently so may need a sooner interval. Just checked/changed pads and checked rotors, cleaned calipers etc so figure it’s likely just faster than usual wear on the dot fluid

If your bottle of DOT fluid is old, it might have just absorbed enough water out of the air that even though it's "new" fluid, it's still got a bunch of water in it and the boiling point is significantly lowered.

[Wes Mantooth]

If your bottle of DOT fluid is old, it might have just absorbed enough water out of the air that even though it's "new" fluid, it's still got a bunch of water in it and the boiling point is significantly lowered.

True, I don't think it's that old, but did read somewhere that it can absorb enough moisture within 2 years to cause problems, even in a closed container

[Dumbest Known Time]

That reminds me of one of more puckering moments on a bike. Descending on one of the 20% steep roads that exits out of Forest Park in Portland on the gravel bike that I hadn't touched in probably 6 months. Braking way too hard and fast, both front and rear shit the bed with no power. If there hadn't been a driveway pointed uphill to serve as my runaway truck ramp I would have either been spit out into traffic at 40 mph or hugged a doug fir at about the same speed.

A thorough bleed fixed it just fine.

[Falcon3]

Diaz Suspension Design has a pretty good series of IG posts going about fork alignment rn. He shows before and after videos and talks about where they find issues. Spoiler: He doesn’t describe exactly what he does to fix things, because that’s how he pays the rent.
It’s the most recent 4 posts on his profile.

Good timing! I sent my Zeb to them a couple weeks ago and they called me about it today. Said my mis-alignment was a "3.5 out of 5" in their experience and was adding significant stiction. I had initially put a custom tune on my service request but they said I should notice a big improvement with the alignment and talked me out of the tune. Pretty stoked to get it back on the bike, I'm really liking the Fox38 I put on but stoked to feel a properly set up Zeb also.

[Roxtar]

Good timing! I sent my Zeb to them a couple weeks ago and they called me about it today. Said my mis-alignment was a "3.5 out of 5" in their experience and was adding significant stiction. I had initially put a custom tune on my service request but they said I should notice a big improvement with the alignment and talked me out of the tune. Pretty stoked to get it back on the bike, I'm really liking the Fox38 I put on but stoked to feel a properly set up Zeb also.

I'd LOVE to see their process for doing this.
The factory forges/casts these things with massive fixtures throughout the manufacturing process to keep everything lined up. I can't imagine how Diaz can tweek these to the minute amount it takes to "improve" on the factory straightness (% of mm) without an enormous investment in machinery.
I hope he's not just doing it by hand and feel.

[toast2266]

I'd LOVE to see their process for doing this.
The factory forges/casts these things with massive fixtures throughout the manufacturing process to keep everything lined up. I can't imagine how Diaz can tweek these to the minute amount it takes to "improve" on the factory straightness (% of mm) without an enormous investment in machinery.
I hope he's not just doing it by hand and feel.

From watching his videos, it seems like how the hub interfaces with the fork is a significant factor. I don't know how much of that is variations in different hubs vs. misalignment of the fork. But it seems like it'd be pretty tough to account for variations in the hubs.

But I wouldn't be surprised at all if the solution was essentially just to bend the lowers a bit with some basic tools, then check the fitment with the CSU. Cost and fancy equipment aside, I'm not sure there's realistically a better way to do it.


Sent from my SM-S901U using Tapatalk

[Andeh]

I'm pretty sure there's something to whatever he does. I have a Zeb that I got from Joetron which Diaz had worked on that is amazing. I have another Zeb that I bought new, honed the bushings myself, upgraded to SKF seals, etc. and it never feels as good. Same 3.1 damper upgrade on both, same oils, etc. The only other difference is the Diaz one is set to 170, the one I worked on is 160. The one that wasn't worked on by Diaz feels like it ramps a lot more in the lower 1/3 of stroke, which I assume is actually some sort of binding.

[frorider]

It’s getting a bit frustrating to read the dozens and dozens of comments on Diaz’s instagram asking him to explain more about what he’s actually doing to ‘align’ and his answers are always variations on ‘yes I am aligning’.

If he wants to omit the details on the actual process that’s fine, but to stubbornly avoid any explanation of what is getting aligned is kinda weird.

I vaguely recall a fork test years ago in which small variations in hub width affected binding force. Is he just trying micro shims (or end cap sanding) to fine tune hub width?

[jono]

That's a legit question, but the answer "yes I'm aligning" seems to imply that he's bending stanchions, doesn't it?

In which case, ok, you could do that with max expense and minimum geometric expertise. But you could also do it a million other ways, including a few carefully mounted dial indicators.

However you do it, once you have the ability to measure alignment accurately you should be able to measure how much you're bending them. Then you build a database for each fork so you know how much "spring back" to expect (a la sheetmetal brake) and it gets you pretty close and adds one to your database each time. If you can improve alignment by 50-90% people will notice.

[rideit]

Let’s get Hambini on the case!

[toast2266]

That's a legit question, but the answer "yes I'm aligning" seems to imply that he's bending stanchions, doesn't it?

That's my take.

I'm also guessing that work voids the warranty (or at least could be used an excuse to not honor a warranty), so it's maybe better left as a "don't ask don't tell" kind of procedure.

It's kind of like pivot bindings and Cast. People want what cast is offering, but pivot definitely doesn't approve of the alteration, and they don't want people to do it even though it makes their product better.

Sent from my SM-S901U using Tapatalk

[Roxtar]

Yeah, there are so many variables to stanchion alignment (direction, angle, material springback, distance, which side is off, etc) that I can't imagine just manually pulling on it would possibly improve anything.
One possible low-tech/lowish-$ solution might be to insert very long rods into the stanchions which would extend far enough to be able magnify any misalignment.
That would still require buying 34mm, 35mm, 36mm, and 38mm (Don't think he works on Manitou) sets of these rods.

[sfotex]

Diaz was talking about facing the dropouts in their last video.
The lower are cast magnesium and soft, so they are going to distort with the hub,
I bet they align the axle holes to stop the lowers from twisting and get the dropouts square and go from there.

Trying to 'cold-set' stanchion tubes without destroying coatings, creasing things, etc. ,not to mention liability, seems like a moon shot to me...

[Andeh]

That makes the most sense out of all of this speculation. The lowers are going to get twisted/bent to line up the axle once the axle gets inserted and tightened down. From the factory, the droputs are probably squared with the holes that are through them, but not necessarily to the opposite side. Like you said the lowers are a really soft material so it wouldn't take much to knock them out of true between casting & final assembly. So it makes more sense to reface them when they're fixed in place by the axle, as that's the actual working condition.

[jono]

Trying to 'cold-set' stanchion tubes without destroying coatings, creasing things, etc. ,not to mention liability, seems like a moon shot to me...

Liability is always arguable, but coatings and creases would be non-issues within this range. It takes about the same force/deflection to put them right as what (theoretically) messed them up.

ETA: I'm thinking of this relative to the steps needed to measure and straighten paired tubes that are about 10x the size of a fork stanchion. During manufacture those get measured and straightened as much as possible before coating but they can be bent as needed afterwards, too. Lot more options on small stuff.

Best reason to think there's no bending needed is that they wouldn't necessarily stay straight for real long. In reality, this would represent a strain relief exercise, so it would take somewhat more force to mess them up again (aside from any cold working increase in YS, but that should be minimal). But the whole prospect is more reliable if we're talking about stress that is well below yield in normal use and can be corrected by machining/shims.

[jono]

This post is probably only interesting to a few of us. You were warned.

My previous post notwithstanding, we're talking about a forged component. Show me a forged, formed or in any way bent component that never leaves the manufacturing process with meaningful residual stresses and I'll show you a process that includes strain relief.

It's not uncommon for manufacturers to accept the best tolerance they can get rather than the one they need. So it's not unlikely that there's a strain relief cycle needed, without which there's a little more variation in alignment and some of the forks will move a little when subjected to large but typically acceptable forces. Given the weight requirements, I'd be surprised if it's all that rare for a fork to yield slightly in use, so I'd expect anyone doing what Diaz does to check and try to correct that. Wouldn't have to be perfect to be better.

[sfotex]

Liability is always arguable, but coatings and creases would be non-issues within this range. It takes about the same force/deflection to put them right as what (theoretically) messed them up.

ETA: I'm thinking of this relative to the steps needed to measure and straighten paired tubes that are about 10x the size of a fork stanchion. During manufacture those get measured and straightened as much as possible before coating but they can be bent as needed afterwards, too. Lot more options on small stuff.

.

If the stanchion wasn't pressed into a crown.. but as it is you would have to grab the crown and bend the stanchion, or hold the stanchion and bend the crown on a 'Kashimi' coated tube that's sensitive to any small knicks in it, etc. And I imagine the uppers are pretty straight when they manufacture them anyways,

I would guess this issue is more of a tolerance stacking thing between the uppers and lowers, seals, and bushings vs. one piece being out of tolerence....

C'dale claims on the Lefty is better because with 2 stanchions when the front wheel gets a twisting force on it it twists the legs and introduces a bunch of friction in the system, and that seems to be true in garage testing at least, so if the dropouts were misaligned I guess it could cause a similar issue?

[jono]

Assuming it's minor, it probably depends on the misalignment, I think. Some would resolve pretty well into the axle. One bad issue would probably be an incorrect length that pinches or spreads the dropouts.

That actually seems like a good thing to check yourself before sending a bind-y fork off for work: how close is the fit without the axle vs. with tension?

I also think C'dale is right, FWIW. By the time you account for flex the over-constrained nature of a dual stanchion fork is almost certain to bind sometime.

[toast2266]

I'm impressed that this discussion devolved into extolling the virtues of the lefty before at least dabbling in some inverted fork talk.

Sent from my SM-S901U using Tapatalk

[XXX-er]

The Lefty Max with SPV worked really well IME especially compared to the forks that were around 20 yrs ago

When I rode the earliest Giant Reign , the rear end worked pretty good but whatever fork was on the front absolutley sucked dead goats while buddy at the C-dale demo just asked me what I weigh adjusted air on a prophet and it was great

but I'm pretty sure a lot more Reigns were sold than prophets cuz of the anti-christ factor