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Flip it and slam it: discussion and how-to guide.

Thursday, May 9, 2013 by  
Filed under Daily Blog


Hopefully the title of today’s blog has you excited! You’ll have to pardon the double entendre, the obnoxious teenager that still lives within me couldn’t resist. Besides, your first thought came from you, not me.

So, to the disappointment of at least some of you (and the relief of others), my blog will remain G-rated. Today we’re going to look at the practice of “slamming the stem”.

“Slamming the stem” is, simply put, lowering a bike’s stem all the way down to the headset bearing cover. In other words, no spacers between the stem and the dust cover. Most people who slam the stem also flip the stem over (assuming the stem has a rise, of course), providing an even lower and more aero riding position.

Why would you want to Slam That Stem? Good question! I’ll start with the reasons why you shouldn’t slam your stem.

First of all, despite what some cyclists would have you believe, slamming the stem is not for everyone. Right now it’s very in vogue to slam. In fact, rolling up to a group of riders with spacers below your stem is, in the eyes of some, tantamount to a Cat. 5 tattoo. Personally I think that’s silly, and I don’t share that belief. Do not slam your stem purely for style points.

I’m going to digress for a moment. The majority of The Rules are practical, and should be implemented if you’re spending any real time in the saddle. That said some of The Rules are just plain dumb. I say do what’s best for you, and who cares what anyone else thinks–especially if you’re fast. It will sting that much more when you drop the guys who just called you a Fred because you’ve got a 5mm spacer below your stem. The only rule that really matters is Rule #5, anyway.

Getting back to the subject at hand…

If you’ve got a belly and/or are not very flexible, you probably shouldn’t slam your stem. You’re not going to look cool or be very comfortable if you can’t breathe, or if your quads are hitting your torso when you pedal.

So, why slam? I’ll tell you why I did it: I’m more aero in all positions, I’m faster and I find it much more comfortable than riding in a more upright position.

The nice thing is you can try slamming your stem without permanently modifying your bike or spending a dime. Simply remove the spacers below the stem and put them on top. This is what I did at first, and after a couple hundred miles I knew slamming was for me. From an aesthetic standpoint stacking your spacers on top of the stem looks like crap (IMO), but it’s important to make sure you’re happy before you cut down the steerer tube. In fact, there’s no law that says you ever have to cut the steerer tube. Lots of people don’t. You’ll have to make that call for yourself.

If you do want to commit and cut your steerer tube, it’s not that difficult. I’ll detail the procedure I used below.

Recommended tools and parts:
Park Tool Threadless Tubed Nut Setter for 1″ and 1-1/8″ Forks (TNS-4)
Star nut assembly (you can also purchase just the star nut and use your old cap)
Park Tool Hacksaw, 12-Inch (SAW-1)
TEKTON 3180 Double-Face Soft Mallet
Adjustable Clamp Vise
Park Tool Threadless Saw Guide (SG-8)
Nicholson General Purpose File Set
Park Tool 3/8″ Torque Wrench (TW-2)
Park Tool Socket and Bit Set (SBS-1)
Park Tool Hex wrenches
Sharpie Fine-Tip Permanent Marker
Low profile headset bearing cover (optional, use if you want to go as low as possible)
.25mm Microspacers (you might need these if you use the low profile bearing cover)


This is a really easy project, but if you don’t fully understand what you’re doing then take your bike to qualified mechanic. Safety first!

Click any of the below images to enlarge.

The first step is to mark the steerer tube where you want to cut it, and then remove the steerer tube/front fork assembly from the bike (you’ll need to remove the front brake assembly to do this).

Start by removing the top cap bolt and the stem bolts. For most bikes you’ll need a 4mm and a 5mm hex wrench to do this. Take the spacers off, leaving the stock headset bearing dust cover in place (or, optionally, replace the stock cover with a low profile dust cover and, if needed, microspacers).

Next, slip the stem back onto the steerer tube and then mark where the top of the stem is on the steerer tube with a sharpie. Make sure everything is nice and tight vertically before you make the mark. You’ll actually be cutting just below this mark, as you want the steerer tube slightly shorter than the stem.

Steerer tube removed. Shown is a custom low-profile bearing dust cover that will replace the much taller stock headset bearing dust cover. As you can see, there is a small gap between the cover and the frame, so I had to use a micro-spacer with this cover.

Steerer tube removed. Shown is a custom low-profile bearing dust cover that will replace the much taller stock headset bearing dust cover. As you can see, there is a small gap between the cover and the frame, so I had to use a micro-spacer with this cover.


Lock the saw guide in the vise, then use a hacksaw to cut the steerer tube a few mm below where you made the mark. Again, you want the steerer tube slightly shorter than the stem. Remember, you can always take more tube off, but you can’t put cut tube back. Be sure you don’t take off too much tube, or you’ll be buying a new one.

Preparing to cut the steerer tube.

Preparing to cut the steerer tube.


Put the the steerer tube back on the bike, slip on the dust cover and stem, and make sure you’re happy with the length of the steerer tube. Then, using the threadless tube nut setter tool and a mallet, install the new star fangled nut in the steerer tube. You can also use a file to smooth the surface of the cut steerer tube if you like.

Steerer tube cut. The Park Tool TNS-4 (left of steerer tube) is loaded with a new Star Fangled Nut.

Steerer tube cut. The Park Tool TNS-4 (left of steerer tube) is loaded with a new Star Fangled Nut.


The Park Tool TNS-4 makes installing star fangled nuts a super easy job. You simply thread the nut into the tool, place the tool on the steerer tube and then hammer it down with a soft mallet.

Using the Park TNS-4 to install the new Star Fangled Nut into the steerer tube.

Using the Park TNS-4 to install the new Star Fangled Nut into the steerer tube.


With the TNS-4 the star nut will be installed perfectly centered and at the correct depth every time. This is a great tool.

New star nut perfectly installed.

New star nut perfectly installed.


Now all you have to do is put the steerer tube back in the bike along with the headset bearing dust cover and stem (most people flip the stem for an even lower profile) and tighten to spec using a torque wrench. Remember to tighten the top cap before the stem bolts! Bounce the front end and check for rattles. Also, check again after the first ride. Here’s the finished product. I really like how it looks, but I love how it rides!

My Madone 5.9 with flipped and slammed stem.

My Madone 5.9 with flipped and slammed stem.


Flipped and slammed: close shot.

Flipped and slammed: close shot.


I hope this was useful. If you have any questions or comments, leave them below!

John Stone Fitness Comments

8 Responses to “Flip it and slam it: discussion and how-to guide.”
  1. A fascinating subject. I’ve read that the main thing which results in higher speeds on TT bikes is not the slippery aerodynamics of the TT bike itself, but the fact that it places the rider’s torso in a nearly horizontal position. The air resistance of an object increases by the square of it’s velocity, if I remember correctly, so even relatively minor aerodynamic improvements can pay big dividends. And the faster you ride, the greater the payoff.

    I did some tests several weeks ago to see how my riding position on the bike affected my speed when coasting downhill. Sitting upright on the bike after crossing the starting line at 10 mph resulted in a maximum speed of 22.8 mph. Getting in the drops and keeping my torso low over the handlebars increased that to 24.4 mph. I performed each test three times to make sure the numbers were consistent, and I’m using a speed sensor on my bike to ensure that the GPS readings are as accurate as possible.

    Getting some extra speed at no cost appeals to me, so I’ve tried to accustom myself to riding in the drops at all times. I’m surprised at how long I can manage it in relative comfort. You may remember a part of the WOT which consists of a long flat section of trail which winds around a golf course. My past ‘cruising speed’ on that section was about 21 mph. Anything faster than that and fatigue would set in. My cruising speed in that section now is between 22 and 23 mph. I don’t know how much of that is attributable to riding in the drops, but it’s a very significant improvement.

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    • I find riding in the drops to be the most comfortable position. I probably spend 90% of my time riding down there. Some of my trainer workouts have focused on developing power while in the aero position, and that training has helped me quite a bit, too (most people find it easier to generate power while in a more upright position).

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      • I’ve noticed that when pedaling hard in the drops, most of the muscle power seems to come from my glutes and hamstrings, whereas in the most upright position, the quads seem to do most of the work. It’s for that reason that when I use the leg press at the gym, I position myself so that my glutes and hamstrings get the most benefit.

        Some time this weekend, I’ll be trying out a trainer like yours to see how long I can tolerate riding in place. If I can manage it for at least half an hour without going mad with boredom, I may just buy one.

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