Strange steering issue
 

So, looking for some advice, have kind of a strange situation. Here is what's up:

-Finished building up a bike with the Nashbar touring frame/fork the other day

-As soon as I take it for a spin, it's clear something is wrong. It feels like an invisible hand is shoving the front wheel to either side at intervals. It feels like a challenge to go straight and not fall, and riding no hands is out of the question.

-I've had old bikes in the past that pull to one side or the other. It doesn't feel anything like that. If you've ever done the physics experiment where you hold a spinning wheel and turn it to feel the gyroscopic forces, it feels something like that, somehow. I have three other bikes and am a pretty experienced rider so I don't think it's my riding ability that's the issue.

-I immediately suspected the headset. I had my LBS install the cups, but I did the rest of the install. I redo it a couple of times, can't find anything wrong, but it does seem like it is oddly difficult to get the headset into the zone where it's not too tight but there's no play. In fact, there's always a little play. I experimented with riding the bike with the headset obviously tight or loose but the issue doesn't go away.

-I take it to my LBS, they fiddle with the headset for five minutes and agree that it seems "off", but don't have time to investigate that day and kind of imply that a new headset will be cheaper than them investing significant time into figuring out what's up.

-The headset is a new Cane Creek 10 series.

So, I'm a bit mystified by it all. Seems like the headset is at fault simply because I can't think of anything else that could cause this, but I can't find anything obviously terribly wrong with the headset. Also the fact that the problem is there even when the headset is way too loose makes me wonder if it's something else.

Before I order a new headset slash try to return this one, has anyone experienced anything like this? Does this sound like a "bad" headset? Or like something else is the matter?

Thanks for any help...

EDIT: before anyone asks, yes I have sufficient spacers extending beyond the steerer so the headset cap can preload the bearings. I am using an expander plug rather than a star nut for the moment until I cut the steerer to its final length (though I don' t know why that should matter).

I suspect it's the headset installation. The type of squirrelly steering you describe is characteristic of a tight or binding headset. That makes it stick/slip as you make the tiny corrections necessary to balance a bike. The handling along with your headaches adjusting point to a headset issue.


My first guess is that one or both bearings are upside down. Or a spacer is missing or something like that. Pull the handlebar stem, drop the fork and take a look.

One other possibility is the steerer rubbing in the lower bearing cup. This used to never happen, but these days some forks have the crown seat bulge extend too high, and overlap in the sleeve area of the lower cup. A high bulge combined with a thick walled headset will bind like yours. Test for it, by removing the fork and seeing if the bulge extends above the crown. Also insert the fork into the frame without the lower bearing and see if it's tight or even rubs the least bit.

If you have a fork/headset rub, the remedy is to use a reamer or half round file to open up the headset's ID enough to resolve it. Note: YOU CANNOT SAFELY REDUCE THE DIAMETER OF THE STEERER CROWN BULGE. SO DON'T EVEN CONSIDER IT AN OPTION.

I guess that's possible....I've certainly checked. The bearings say "Aheadset" and then a part number on the outside. I assumed they were to be installed with the writing right-side-up. Could that be wrong?

OK just cross referenced this pic http://www.treefortbikes.com/images/raw/TF-HD0048-2.jpg with the instructions and it is clear I've installed one of the bearings upside down! Thanks FBinNY. Will report back.

The bearings are the same but asymmetrical, with an internal conic bevel on one side and an external on the other. The external bevel goes into the cup, the internal bevel fits the conic crown race, or centering cone on top.

On your headset the sequence from the bottom to top is: cone -cup-cup-cone. So the bearings would also mirror, one up, one down.

Whoops look like I edited as you were replying. In case case you're absolutely right, I installed one bearing upside down.

Could be worse, might have been both.

There's a lesson here, and that's not to be fooled by writing or assumptions, but to pre-assemble parts in your hand so you can see what fits where. Nine out 10 times, if you give them a chance the parts themselves will tell you how they are supposed to fit.

That's true. In any case, just rode around the block, feels normal now. Thanks!

What would we do without FB?

Yeah. I for one is sure glad he's on this Board.

Now, if we can only have him solve this little "Syria" mess.

Syria's easy, have you ever looked at the A&S forum?

Here, here. Observation of how things fit together and interact with other parts is what makes one successful in working on anything mechanical. Following rote instructions works great when you're in a Park tool laboratory situation, but in the real world Murphy's law rewards the observation, manipulation, and logic.

Seriously. Besides the fact that he's knowledgeable, he's one of the few who will always be helpful without passing judgment or asserting superiority.

I know people here just love saying this, but he said the LBS didn't really have time for it that day. Doesn't sound like they disassembled anything, just tried to make an adjustment. I'm sure they would have caught it if the bike had been left there.

I don't say anything because I love saying it; I say it because it's what I think. Maybe the LBS suggested it was installed upside down, but the OP didn't say that. They suggest a new headset instead of checking their cup installation. I stand by my statement.

I don't know if they would have found the problem. The mechanic seemed to be of the replace instead of fix mentality. Here's the key sentence from the OP.

Dry friction, such as the upside bearing would have caused is very characteristic, and any mechanic worth his salt should have felt it just by twitching the bar. Of course he might not have known the cause, but this isn't something that;s cured by replacing a headset. The sad irony is that they could have removed and replaced the headset without spotting the bearing, and the new one would have worked, validating their sloppy diagnosis.

The skills most lost in shops today relate to diagnostics. Mechanics cannot look at signs and translate those to possibilities. Also many mechanics are simply "component hangers" who can set up new equipment fine, but lack the fundamental skill and knowledge to solve problems and make stuff work.

True, but it's for him to decide. Only he knows exactly what was said there. You're right though, that does seem a lazy diagnosis.

You're right, in fact I was trained by someone who thought and worked this way. I'd say, "don't we have any spokes?" and his response would be "it's easier to just replace the wheel." Sad, especially because most people didn't doubt the diagnosis. I've always gone about things differently, but unfortunately that meant I had to teach myself (which is why I often end up here).

Hate to say it, but I agree. It would have taken a couple minutes to drop the fork and check out the bearings. Why look at it at all if you can't take 5 minute to check out a headset issue?

I'm more forgiving of that. The store might have busy, and a real evaluation could have been time consuming. Had the mechanic said "something's rubbing, but I don't have time to look at it" I would have been fine. But to imply (if he, in fact, did) that a new headset could be less costly than "fixing" this one shows that the mechanic lacks skill and knowledge, especially when you figure that a new headset means knocking off and replacing 3 pressed on parts.

These days too many mechanics are too quick to say "this is broken, you need a new one". I translate this to mean "this is broken, you need a new mechanic". Of course this isn't always true, some things can't be fixed, or at least not economically, but too many mechanics cannot fix anything.

I once watched a mechanic align a hanger twice. The RD didn't index right, so he removed it and used a Park tool to align the hanger. Installed the RD which still didn't work, so off it came, and the park hanger tool went back. Really, what did he think was going to change in the hanger alignment? Or didn't he trust his first effort?

Grrrr, you awoke my inner grammar nazi. Why not tell us how to adjust breaks? If you speak loudly enough, we might all be able to here what you're saying.

You need this...don't ask why I have it. :D
http://bikeforums.net/attachment.php...hmentid=339486

Okay, that made me chuckle out loud! I thank you. I may have to steel that....

Not a spelling nazi apparently :rolleyes:

So, you saw what I did there, huh?