During my roundabout bike ride home from the Honda dealership yesterday, I stopped in at Ti-Cycles to ask about the "pedal bob" I've noticed on my Moots. Several people have commented that there is a good 1/2 inch of pedal bob when I'm pedaling on flat, smooth surfaces. I rode alongside another YBB owner on Saturday and her soft-tail only compressed about 1/4" and she said that it looked as if mine definitely compressed too much on the flats.
My immediate thought was that my bike possibly shipped with the wrong spring, so I explained the problem to Brian at Ti-Cycles who promptly called Moots and relayed the problem. I was on my road bike so there was no way to take apart the YBB right then and there, but I was told to go home, follow the YBB rebuild instructions that came with the frame and see if the spring inside is yellow or red. Red is for lighter folks, whereas mine should be yellow.
Taking apart the rear-end of my brand-new bike was among the last things I wanted to do with the new steed, second only to taking a hammer to it! And lookee here... the manual says to use a "dead blow hammer" to reinstall the slider.
Do I really want to go here?
I put the bike in the stand, took off the wheels per the instructions, and undid the bolts on the coupler. A quick use of a flat-head screwdriver later and the precious grease-covered YBB "suspension" assembly was in my hand.
Great. The bike had the proper spring. Now I have a greasy mess in my hand for nothing. Time to reassemble.
I followed the instructions word for word but couldn't get the slider assembly back into the couplers all the way. I tried the rubber mallet. I tried a block of wood and a metal hammer (gently, very gently) and I tried giving it the stink-eye, followed closely by the evil eye. None of this worked.
So I called Moots. I was first forwarded to Dave who also rides a Mooto-X YBB and he assured me that the pedal bob I was noticing was normal. That some riders experience it more than others on flat, paved bike paths because they pedal more in squares than in circles. He understood my concern, but reiterated my initial thought that it was a very simplistic design that either allows for some compression or doesn't. It's either on or off and the oscillations in some people's pedal stroke can accentuate the compression... especially on flat, paved, bike paths. Oddly enough, it's exactly that type of terrain on which I notice the most bob. It'd be nice if they make a heavier spring available in the future, but my worries have been allayed. But there's still a matter of a spring that won't go back in...
Dave put me in contact with Sam, the man who did the final assembly on my frame just a few weeks earlier. Gotta love dealing with small companies -- can you imagine calling Trek and trying to reach the person who installed the bushings on your frame? Good luck trying! I digress. Sam walked me through the process of reinstalling the YBB assembly and was satisfied that I was doing everything correctly. He then shared some tricks of the trade that he's learned over the years, but this still didn't result in a reinstalled YBB assembly. We concluded that I needed a second set of hands and that I did need to go buy the "dead blow hammer". I never heard of this type of hammer, but he said it was a plastic mallet filled with sand. Sounds like a toy I had as a kid. Hmm....
Neither of the two hardware stores nearest me carried this mythical tool so I headed home to at least take advantage of the one thing I did now possess -- a second set of hands. Kristin applied pressure to the top of the seat-stays while I continued to use the rubber mallet. It still wouldn't go in.
Now, if you're a YBB owner who stumbled to this article by frantically Googling for advice to this very problem, you're in luck! I have the solution right here. Through much trial and error -- and a dose of unneeded frustration -- we figured out how to do this quick and easily. And without the need for any hammer!
Loosen the bolt on the lockout collar and make sure the set-screws are partially withdrawn so that the slider assembly is not bumping into anything. Now, using your hands slide the slider assembly through the collars as far as it goes, per the instructions provided by Moots. Now, instead of reaching for the hammer, gently reinstall the two bolts in the lower collar at the top of the seat stays. Using a soft-surface bar clamp, squeeze the slider assembly through the lower collar by putting one end of the clamp behind the bolts on the seat-stay collar and the other on the slider assembly. It doesn't hurt to have a helper apply steady pressure to the chain-stays during this process. The problem wasn't that the slider assembly wouldn't go far enough into the upper collar, but rather that the seat-stays were flexing upwards out of position. Use the seat-stay collar against itself to pull it downward over the slider assembly. Once you have the assembly flush with the bottom of the seat-stay collar, reach for the 4mm hex wrench and tighten the two bolts in the collar, alternating between the bolts one turn at a time. Re-tighten the bolt in the lockout collar (not all the way, obviously) and reinsert the two set screws until they are below the surface of the collar.
There you have it! Remove the bar clamp and continue to tighten the two bolts on the lower collar one turn at a time on each bolt to make sure it sets evenly across the somewhat pliable titanium.
The bike is back together. I know I have the right spring and that it's working the way it should. And I know that when I need to do the YBB rebuild in the future for real, I can easily do it myself. Hope this helps.