PDA

View Full Version : Headset question - handlebars sticking straight ahead


moose8
04-11-2013, 08:34 PM
I just switched the stem on one of my bikes and when putting the new one on I noticed the handlebars really want to go straightforward - imagining straight ahead being 0 degrees, the handle bars turn smoothly 45 degrees either way but really catches while straightforward. It is a threadless headset. I didn't notice this before I switched the stem, but that doesn't mean it wasn't happening. Does it sound like the headset is bad? Or I adjusted it wrong? I loosened everything and it still catches going straight without the star nut cap or stem attached. It probably only has 1000 miles or so on the bike, so I would be surprised if it was wearing out. Thanks in advance

ultraman6970
04-11-2013, 08:49 PM
???????

lhuerta
04-11-2013, 08:55 PM
make sure your bearings are seating back in correctly. Try installing the old stem and see what happens. If it only happens with the new stem then its possible that the face on the stem is off yielding uneven compression on your bearings. Yes, sometimes stems do have uneven faces.
Lou

vqdriver
04-11-2013, 09:14 PM
try the old stem as mentioned above.
also keep an eye out for the housing catching/pushing on each other or the brakes or cable stops or whatever. it always seems like a chaotic mess to me.

nooneline
04-11-2013, 09:17 PM
this is called "headset getting indexed."

if it's not totally screwed up, you can fix it by re-greasing your bearings and setting the preload on your headset a bit lighter.

rustychisel
04-11-2013, 09:31 PM
You should be able to feel the headset bearings 'notch' into position if its indexing, as vqdriver mentioned. For a 1000 mile bike that's unusual unless it's been torqued down HARD.

More likely have a look at the cable run; especially for bikes with headtube stops the cable outer length has to be cut 'just so' to allow untrammeled and straight steering.

David Kirk
04-11-2013, 09:33 PM
The classic 'index steering'

What type of headset is it?

dave

moose8
04-11-2013, 09:41 PM
Wow - thanks for all the suggestions. I'm going to start with putting the other stem back on. It's a FSA headset - kind of generic looking. It came stock on the bike, which is a Rocky Mountain Sherpa 30. It really almost locks in totally straight, and is smooth outside of anything but straight ahead.

Marburg
04-12-2013, 12:18 AM
+1 on being indexed. Since the headset spends so much time in one position it can develop wear in the races which will tend to trap the balls in that one place. Can be made worse if the cups installed perfectly, if it's been torqued down too hard, or if there's some odd differential pressure like the stem suggestion.

That said, I've been able to delay the inevitable in the past by disassembling the front end, spinning the bearings a bit (so the balls go to a different place in the race) and reassembling. Won't fix the problem, but at you'll reset the indexing clock.

Lazer
04-12-2013, 08:56 AM
Brunelled.

oldpotatoe
04-12-2013, 09:12 AM
Brunelled.

didn't know he worked on bikes.

http://espn.go.com/nfl/player/stats/_/id/445/mark-brunell

avalonracing
04-12-2013, 09:16 AM
A "fix" I have found for an indexed headset is take the HS bearing cups out of the frame and rotate one 90 clockwise and the other 90 counter-clockwise and reinstall.

David Kirk
04-12-2013, 09:21 AM
A "fix" I have found for an indexed headset is take the HS bearing cups out of the frame and rotate one 90 clockwise and the other 90 counter-clockwise and reinstall.

right on.

dave

moose8
04-12-2013, 09:30 AM
Thanks again for all the suggestions. This forum is great for getting knowledgeable people to give good answers. I googled headset indexing and it sure seems to meet all the symptoms - especially the "snapping" into place I found reference to on Sheldon Brown's website. Looks like I finally have a use for an old headset I saved just in case.

bobswire
04-12-2013, 09:45 AM
A "fix" I have found for an indexed headset is take the HS bearing cups out of the frame and rotate one 90 clockwise and the other 90 counter-clockwise and reinstall.

I use a marking pen and put a dot on cups before taking them off so I can
set them back at 90 .

http://i48.tinypic.com/2v3n71l.jpg

palincss
04-12-2013, 09:48 AM
I just switched the stem on one of my bikes and when putting the new one on I noticed the handlebars really want to go straightforward - imagining straight ahead being 0 degrees, the handle bars turn smoothly 45 degrees either way but really catches while straightforward. It is a threadless headset. I didn't notice this before I switched the stem, but that doesn't mean it wasn't happening. Does it sound like the headset is bad? Or I adjusted it wrong? I loosened everything and it still catches going straight without the star nut cap or stem attached. It probably only has 1000 miles or so on the bike, so I would be surprised if it was wearing out. Thanks in advance

In other words, indexed steering?
http://sheldonbrown.com/brandt/indexed-steering.html
http://sheldonbrown.com/headsets.html

jvp
04-12-2013, 10:07 AM
If you do the cup rotation "fix", you may want to rotate the crown race as well. I believe most of the brinelling occurs on the lower cup/race.

David Kirk
04-12-2013, 10:29 AM
One other thing that can be done to extend the life of the headset when rotating the cups is to take the balls in races and replace them with loose balls. This is very effective as it greatly decreases the load on each ball and changes the spacing between the balls.

It's easy enough to do once you have a bag of balls the right size......with everything good and clean fill the cups with grease and press the balls into the grease. Load all the balls in and fill the cup. Once the cup is full remove one and call it a day.

This was super common with campy headsets when I was a kid and I can't tell you how many times we had bikes come into the shop with indexed steering that we fixed this way. Takes only minutes to do and will save the headset.

dave

Ralph
04-12-2013, 10:43 AM
YEP....That's what we always did. Never considered throwing away a Campy headset until it was used up using non caged balls. 5/32's as I recall.

moose8
04-15-2013, 12:57 PM
I took it to Harris Cyclery and they diagnosed it as indeed being the headset - they showed me how the ball bearings had worn away the coloring from the part they are in - they said the headset had likely been installed too tightly when the bike was put together initially, and that caused the indexing. They replaced it with a cane creek 110 I bought on clearance thanks to someone posting a PSA here and now it works great. They even did it while i waited, which was nice.

AngryScientist
08-28-2014, 07:56 AM
my Miyata has a tange threaded headset installed, came with the bike as i bought it very used. when i built up, i pulled the bearings out of the headset, cleaned and greased everything, and put it back together. it has a pretty noticeable indent, or index when the bars are straight. the bike rides just fine with the index, cant notice it when moving, but it's definitely there. anything i can do about that short of replacing the whole headset?

moose8
08-28-2014, 08:01 AM
I ran into this problem awhile ago and people had some ideas:
http://forums.thepaceline.net/showthread.php?t=127750&highlight=Indexed+headset

Basic conclusion was it was best to replace though.

AngryScientist
08-28-2014, 08:05 AM
got it, i'm merging these threads now. pretty much what i thought. .

AngryScientist
08-28-2014, 08:05 AM
good stuff here.

pinkshogun
08-28-2014, 08:08 AM
replace the caged bearings with loose ball bearings. a new headset for 1" threaded bikes isnt expensive, look at the Tange Seiki Passage headset and make sure you get the correct size...crown race is either 26.4 or 27.0mm, cups are diff sizes too

druptight
08-28-2014, 08:29 AM
Learn something new every day on the Paceline! Fantastic thread.