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I'm not 100% sure, but I think that the more off road oriented tires also have stiffer sidewalls for this (and other) purposes. I have done some pretty tough rocky trails on my strom with a Mitas E-07 Dakar on the front, hit things very hard, and never bent my rim. I'm surprised you are riding stuff this hard on those tires. I have Shinko 704/705's on my WR and I can't wait to get them off of there. Last year at a single track course with my strom the instructor looked at my E-07s (a 50/50 tire) and called it a street tire.
 

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Just out of curiosity, to what extent can these cracks extend all the way from the inside to the outside? As we are using tubeless tires, could this be a source of leaks as well?
It is possible, but I would expect the leaks at the tire/rim bead area first.

Fatigue cracks are hard to see without using some form of magnification, or even better, using a dye penetrant that wicks into the cracks and is florescent under black light. Machine shops use dye penetrant on engine parts like cylinder heads and my company uses it when we are checking welds or for fatigue cracks in metal assemblies.

If you look for a crack, it will start on the tension side of the bent part. Like on your wheel, the crack should be on the inside edge of the bead, centered in the inward curve. When you bend it back, you now put tension on the outside edge of the bead and the crack should be at each end of the bent section.

Fatigue cracks always start on the tension side and propagate through the interior until they reach the far side, which is in compression (if bent in one direction). So cracks will be wider on one surface (tension) than the other (compression). On parts that are loaded cyclically, like say a trailer hitch, the side in tension switches back and forth as the trailor pushes down on the hitch and then pulls back up when the suspension acts. A fatigue crack on that type of part will start on the top and bottom faces and meet in the middle.
 

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I'm not 100% sure, but I think that the more off road oriented tires also have stiffer sidewalls for this (and other) purposes. I have done some pretty tough rocky trails on my strom with a Mitas E-07 Dakar on the front, hit things very hard, and never bent my rim. I'm surprised you are riding stuff this hard on those tires. I have Shinko 704/705's on my WR and I can't wait to get them off of there. Last year at a single track course with my strom the instructor looked at my E-07s (a 50/50 tire) and called it a street tire.
My playing around with tires agrees with the above. Trail tires are stiffer than street tires in the sidewall and bias ply are stiffer than radials.
 

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Uhhh, a Mitas E-07 a "street tire," really?? That's special.

You're right, the Dakar version of the Mitas E-07 (and E-07+) definitely does have extra sidewall layers, making it stiffer and heavier. IIRC it's also a bias-ply tire (too lazy to go out to the parking lot right now).
 

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Uhhh, a Mitas E-07 a "street tire," really?? That's special.

You're right, the Dakar version of the Mitas E-07 (and E-07+) definitely does have extra sidewall layers, making it stiffer and heavier. IIRC it's also a bias-ply tire (too lazy to go out to the parking lot right now).
Well, it was a single track course. And the instructor seemed like he was a pretty hardcore rally guy. This is a preview of one of the annual rallies they host.

 

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Why......Rich said that isn't what caused your rim to muck up and I agree 110%? If you are doing such for a better ride quality or set up for YOU, than I do agree with that, otherwise you would be getting a false sense of security for better protection.
The suggestion was that with stiffer springs and damping that the suspension may not be able, as it is currently set up, to effectively absorb the harsh impacts to which the bike is being subjected.
 

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The suggestion was that with stiffer springs and damping that the suspension may not be able, as it is currently set up, to effectively absorb the harsh impacts to which the bike is being subjected.
The springs will have essentially zero impact on the rim denting, unless they are soft enough to allow hard bottoming. High speed compression damping could be a minor contributor.
The main things are the speed, the size and shape of rock, and what the rim is made of.
 

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Discussion Starter #48
I'm replacing my wheel this morning.

I've been dealing with: harshness, zero fork compression when I sit on the bike, strange "sproinging back up" action when releasing the front brake while in motion.

I removed my fork brace as a step to remove the wheel. Was struck by a thought, so I hopped on my bike, and...the fork now compresses when I sit on the bike.

:doh

I have a feeling that's gonna help a bit!

So I'm not going to mess with the forks, except to make sure the oil level is the same in both of them, and clean up a small leak in the left seal.

Then set the sag, and go ride without the brace and see how it feels.

My life: simply a warning for others. :)

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Wait wut. How would a fork brace cause any of that?
 

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Discussion Starter #51
Well, it just hit 90F in the garage, so I'm done for the day. :)

All is back together minus the fork brace, and I was able - with full preload - to get just under 35mm of sag in the front.

Time for food, shower, and then a test ride. Should I test on the road that bent my last rim??

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If your fork brace is causing excessive stiction, you either have a bad or the wrong fork brace or a bent fork. A fork brace is designed to hold your forks in parallel.
 

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If your fork brace is causing excessive stiction, you either have a bad or the wrong fork brace or a bent fork. A fork brace is designed to hold your forks in parallel.
Well, the main intent is is to keep the fork sliders at the same level relative to to the stantion tubes, keeping the front wheel in same vertical fore-aft plane as the frame.
You’re right about the bent fork tubes though. And they don’t have to be bent much, less than you can easily see just by looking can be enough.
Given that the OP has had two rim-bending hits, and likely a good number of lesser but still significant ones, I think the odds of his forks being perfectly straight are pretty low.
 

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Oof, that's bad news OP...bent forks are enough to total a bike. :(

Maybe you're lucky and it's JUST a bent tube or stanchion - maybe the triple tree is still true. It's a pretty stout casting.
 

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Oof, that's bad news OP...bent forks are enough to total a bike. :(

Maybe you're lucky and it's JUST a bent tube or stanchion - maybe the triple tree is still true. It's a pretty stout casting.
?? Forks tubes aren’t that expensive, and I can’t imagine a lower triple is crazy money either.

A very slight bend isn’t big deal, I’m sure there’s lots of people out there with slightly tweaked tubes that are none the wiser.
For anyone curious about theirs, the easiest way to check is to remove the wheel, fender and other stuff attached to the tubes and then loosen the triple clamp pinch bolts just enough to allow you to rotate the tube in the clamps. If the tube is bent the bottom of the fork leg will describe a small circle instead of just rotating.
The most certain way is to disassemble the forks and roll the tube on glass plate or granite countertop, but if the bend isn’t enough to see with the first method then it’s not enough to matter.
 

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Discussion Starter #56
Well, bent tube or not...I seem to have my bike back. :) I just went for a test ride with the fork brace off, and gee...everything I described above has been taken care of.

*Harshness: gone; just a little firm as expected with SonicSprings and new oil
*Zero fork compression when I sit on the bike: gone; I can properly set sag now (and I have)
*Strange "sproinging back up" action when releasing the front brake while in motion: gone; behaves as expected now

I can most certainly feel the need for a fork brace now (I've had one on since I bought the bike); just slightly "loosey goosey" over tar snakes and other pavement irregularities. Not terrible, but I do notice it.

There's about 100 yard long dirt side-road near my house that emulates almost perfectly the first road that I bent my rim on. I drove back and forth a few times on it, and wow...what a difference! Not only does the bike now mostly soak up the bumps, but the same types of rocks that bent my rim before had almost no effect on the ride. Also significant is the lack of noise; I no longer feel like I'm beating the crap outta my bike. And, driving thru a rocky, deep rut is almost a no-brainer; just drive thru it. The last time I just bombed on thru at high speed, and it felt like I expected it to feel.

I'm pleased! I'll be spinning my fork tubes as you suggested, Rich, and it also looks like I'll be replacing one of the fork seals, as it's leaking pretty good. Hmm. I suppose if the tube is bent just right, the seal would probably leak? Then I bet I know which tube I need to fix.

Tomorrow! (maybe)
 

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...Hmm. I suppose if the tube is bent just right, the seal would probably leak? Then I bet I know which tube I need to fix...
Probably not. The bend is usually right below the lower triple and the fork seal doesn’t travel over it.
 
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Discussion Starter #59
Thanks Rich; good info!

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