Marzocchi ETA drag?

[Particle]

So Mr. Altagirl was telling me about this phenomenon this spring in Moab. He explained that basically when he engaged the ETA function on his 66 Light, he felt a 'drag' on the bike - like it was harder to pedal uphill, like you were pushing against something. It really should be easier to pedal uphill with an effectively steeper HA. He also said that the Go-Ride guys had received other reports of this same issue.

Anyway, I thought he was smoking something since I'd never experienced that on my 66, or the previous years on my All Mtn 1 and Z1 with ETA. Then a couple weeks ago, I was climbing Collins Trail over near the Canyons in Utah...left the fork at full travel due to the super rocky start to the climb, and then switched on the ETA. Felt like I was pedaling in molasses. It was bizarre. I picked up the bike and spun the wheel to see if there was some resistance, the feeling was so strong. I raised the fork to full travel and I felt like the resistance was gone again. Put it back down, and tried riding it compressed for a while, and while I was able to ride like that, and the resistance feeling started being less noticeable, it still felt like it was there and maybe I was just getting used to it.

So anyway, my theory is that it's a mental thing, and the dramatic change in body position puts your weight so much more over the front of the bike that it feels like you have more pedaling resistance. And possibly there is due to more weight on the tires/more traction between the knobs and soil? The perplexing thing to me is how I never experienced it in many years of riding ETA forks...and suddenly it just happened one ride on my 66. Maybe there is something actually going on...

So anyone else experience this?

[bagtagley]

Yeah, I've definitely experienced it. It's mostly when you mash the travel down on a flat section before a climb. If you do it into a climb, it's not really noticeable. I always use the ETA going into the triple climb on the Crest before it peaks out. Mine creeps up a bit, so on the flat before the final climb, I smash it down real good. It's probably the combination of already being worked from the climbs, but that's where I notice it the most. It can be kinda demoralizing.

I've always just assumed it was the change in geometry. Given your intro, I was expecting you to reveal some strange quirk that caused rotor rub or something.

[bio-smear]

Does it cause deflection of the brake housing, causing a slight engagement of the caliper??? Very weird.

[phatfreeheeler]

I've studied this pretty heavily since I've got 3 forks with this feature. It's not always there, but sometimes it sure is. As I'm sure you know, the way ETA or the old ECC works is to increase rebound damping to an "almost" locked out amount, but only on one leg of the fork. This means the other leg is trying to extend the fork, but is restricted by the other leg. While they are pretty rigidly connected there will always be some flex from this force. It should be less with 20mm axles but it will still be there to some degree. The flex can sometime cause rotor rub in the caliper or I what I believe is some pinch forces in the front axle. The reason I believe it's not always present is mostly tolerances. Hubs are tight tolerance beasts. If you've ever adjusted a King hub I'm sure you know what I mean.

To show this phenomenon. Put your bike in a stand and spin the front wheel. Now lock your wheel down with the ETA and put the bike on a stand. Spin the wheel, I bet it spins less freely. Sometimes mine doesn't do, but usually it does. Sometimes readjusting the QR is enough for it to go away. It sucks enough that I sometimes don't use the ETA feature at all.

[Mr. Altagirl]

Call me crazy but....it's real. PFH has a good explanation, at least it makes sense and allows me to sleep at night.

[Particle]

I don't think it's brake rub, or I'd hear something when I spun the wheel. I kinda like phat's idea of some kind of axle pinch...twilight zone stuff right there.

[pechelman]

meh
ive never noticed anything on my am1

course i suck at climbing anyway and would just attribute my sucking wind to me being out of shape.

[Particle]

meh
ive never noticed anything on my am1

I know. I never felt it on my AM1 or Z1. Maybe the 66 is such a long fork that it creates enough torque with one leg pulling against the other that it 'pinches' the axle? And of course I never felt it on my 66 after months of riding it, until 2 weeks ago. Which is why I can't figure out if it's a trick of the mind or real.

[phatfreeheeler]

I actually have it on my AM1. I kinda think the woosy DT swiss 240 hub is part of the problem for me.

Back in the day of V-brakes it was really bad. My Marathon was awful when locked down. Marzocchi even acknowledged the issue and said discs were the solution. Then I got a Z1 with discs and it was still there