Advice on reversing stem

GeorgeShaw

As an old codger buying his first new bike for many years last year, I had it set up with the stem in the "relaxed" position, angled upwards. I'd now like to try it out reversed back to the "standard", more-aero, position.

Is there a guide on the web about how to do this?

Looking at it, it seems simple enough, but do I have to undo allen key on the steerer cap to slide the stem off?

Finally, will this affect my riding position so that I should move some other components? For example, bringing the seat forward.

Garybee

Flipping the stem will give a large change in the height of your bars. It would be better to alter the height of the bars more gradually by moving spacers from underneath to above the stem first. When you have no more spacers underneath the bar, measure the height of the bar, flip the stem and add spacers underneath to give you a smaller change in bar height.

The top bolt on the stem cap applies a force to the headset bearings. You will need to remove the top cap, remove the stem, add/remove any spacers, refit stem WITHOUT TIGHTENING STEM CLAMP BOLTS, refit top cap and adjust tension of headset bearings, tighten stem clamp bolts.

The order you do this in is important. If you tighten the clamp bolts when you refit your stem it will not allow the top cap to apply load to the headset.

Gary

GeorgeShaw

Thanks Garybee. Not as simple as I thought then ... I'll probably get my LBS to do it.

It'll be a good excuse to spend some time looking at some more kit ...

formerlyknownasbonj

no - it is simple. 'Adjust tension of headset bearings' basically just means tighten the bolt through the top cap into the star fangled nut. You just have to make sure you do this before you tighten the stem bolts.

carlstone

I was going to do this also. My question would be, what is the right tension for the headset bearings, if you have no torque wrench?

alfablue

I tighten the bearings so that there is no play (if you move the bike fore and aft with the front brake on you can feel play) and so the bearing turns smoothly (turn bars side to side) with no resistance. After a ride, check again and adjudt if necessary.

carlstone

Cheers Alfablue

Blonde

To the OP - in response to your question "will this affect my riding position so that I should move some other components? For example, bringing the seat forwardP"

It is generally considered to be a *Bad Thing* to alter the saddle fore/aft position if it is comfortable and set up correctly already. This is the one factor that tends to stay the same on a bike whether you raise/lower the saddle or change anything else because it has to do with the relationship of your position on the bike with that of the bottom bracket and pedals rather than with the handlebar.

From Sheldon Brown: 'Front-back position: Saddles are also adjustable back and forth. Ideally, this adjustment should be made to set the saddle at the correct distance behind the bottom bracket, so that you are pedaling at an efficient angle. The conventional wisdom is that, when the pedal cranks are horizontal, you knee cap should be directly above the pedal spindle. See Keith Bontrager's article on this topic.

It is generally considered a Bad Idea to tinker with saddle position to adjust the reach to the handlebars; it is better to adjust this by replacing the handlebar stem with one with a different reach, or by buying a bicycle with a different length top tube.

The angle and the front-back position are both adjusted by the clamp on the seatpost.'

alfablue

just to add, for clarity:

when checking after the ride, remember to loosen stem bolts first, then re-tighten after adjusting bearings.

When checking play, put your hand around the bottom of the headset where the forks enter, you will feel any play there while rocking fore and aft with the brakes on

nicklouse

i prefer the move the wheel to 90 degrees apply the brake and then try moving the bike as this help remove any movement in the brake confusing the issue.

but the hand positioning also does this.

GeorgeShaw

Blonde wrote:

To the OP - in response to your question "will this affect my riding position so that I should move some other components? For example, bringing the seat forwardP"

It is generally considered to be a *Bad Thing* to alter the saddle fore/aft position if it is comfortable and set up correctly already. This is the one factor that tends to stay the same on a bike whether you raise/lower the saddle or change anything else because it has to do with the relationship of your position on the bike with that of the bottom bracket and pedals rather than with the handlebar.

From Sheldon Brown: 'Front-back position: Saddles are also adjustable back and forth. Ideally, this adjustment should be made to set the saddle at the correct distance behind the bottom bracket, so that you are pedaling at an efficient angle. The conventional wisdom is that, when the pedal cranks are horizontal, you knee cap should be directly above the pedal spindle. See Keith Bontrager's article on this topic.

It is generally considered a Bad Idea to tinker with saddle position to adjust the reach to the handlebars; it is better to adjust this by replacing the handlebar stem with one with a different reach, or by buying a bicycle with a different length top tube.

The angle and the front-back position are both adjusted by the clamp on the seatpost.'

Thanks Blonde. Very clear.