Handlebar/front wheel turns too easily - loose steering?

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Thursday guy

Active Member
It's so sensitive. I can't leave my bike resting parallel against a wall without the handlebar rotating all the way through, causing the bike to fall. I've seen people push their bike along a straight line without having to constantly hold onto the handlebar, whereas for my bike, I can't do that. I don't think the bike is too heavy, it weighs about 13kg.

I'm not sure if this problem is loose steering which is a term I've heard about but don't know much. Nothing feels dangerously loose. The issue is the handlebar and front wheel rotating too easily, and I wonder if there's anything I can do about it.

I've attached a photo of the bike's handlebar stem. What's affected if I turn the allen key hole on the stem?
 

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Basic test

Place wheel on solid surface

Grasp handlebars and apply front brake firmly

Rock back and froward

If there is play in the headset then the adjustment is too loose
 
There is a system that holds the bearings in place and their tightnrss is what alows the bars to turn and how stiff the turning is:

Headset.jpg


This is what determines the tightness of the steering. If it is too loose then the assembly will move when tested.

Tighten up the adjustable cap until this play has gone.

Overtightening will cause increased wear on the bearings and the cups

This video will explain better than I can:


 
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Thursday guy

Thursday guy

Active Member
Cheers. So maybe I'll have to put up with the loose steering if I don't want the handlebar stem to wear away. But what do you mean by rocking the bike back and forth? Do i just stand next to the bike, apply the brakes and try to push it forward and backwards?

also, would turning the allen key hole on my stem tighten up the steering?
 
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Thursday guy

Thursday guy

Active Member
Rock it back and forth while you stand next to the bike grabbing hold the front brake lever tight - if there is any play in the headset you will be able to tell.

If that is not it then what you have is over-sensitive steering caused by inadequate trail, see http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_geometry - it can be caused by forks too short or similarly headtube angle too steep.

Sorry for all these dumb questions, what is this 'play' that I should be noticing while rocking the bike back and forth?
 

RecordAceFromNew

Swinging Member
Location
West London
You will see and feel play between the stem and the headtube, which shouldn't happen. BTW the top allen key should be on tight and losening it would allow the stem to move independent of the forks, which you definitely do not want.
 

vickster

Legendary Member
Maybe take it to a shop if you're struggling ;)
 

Dogtrousers

Kilometre nibbler
Push bike forward and back with front brake on. If there is a mechanical knock with each push (or pull) it's loose. If not, it's fine. It should be as free-turning as possible, without knocking.

Pushing the bike while holding just the saddle and not the bars is a bit of a skill, not related to the steering.
 
Sorry for all these dumb questions, what is this 'play' that I should be noticing while rocking the bike back and forth?

"Play" is a technical term for looseness in a joint or fixing that should not be there

If you watch the video you will see how the black part at the top of the stem is moving... this is the "play"
 

boydj

Legendary Member
Location
Paisley
Cunobelin's diagram is for a threaded headset, which I don't think you have. Loosen the top cap and make sure that it is tightening on the stem and not on the top of the steerer. The top of the steerer should be below the top of the stem, and if not you need a spacer in there. That's assuming that the fork is the right way round in the first place and not trying to correct itself.
 

Wobbly John

Veteran
The photo with the original post shows a quill stem and the forks the right way round, boydj.

Thursday guy, the allen key bolt in the middle of the stem is connected to a wedge that holds the stem in. Loosening it allows you to adjust the handlebar height and alignment.
Handlebars and forks should turn easily. it would be difficult to ride otherwise.
Follow the video upthread or take it to a shop if you think there is play in the headset bearings.
 
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