A. Do You Need Handlebar Shims?

B. How to Choose ShockStop Angle

C. How to Choose ShockStop Length

D. How to Choose Mount Type

E. Difference Between Drop and Flat Bars

A. Do You Need Handlebar Shims?

The ShockStop handlebar clamp is 31.8 mm which is compatible with many modern bikes, without the need for shims.

We also have shims available for 26.0 mm and 25.4 mm handlebar sizes.

• 25.4 mm is common on bikes with flat handlebars
• 26.0 mm is common on older road bikes with drop handlebars
• There are other less common sizes that we do not provide shims for.

The easiest way to determine your handlebar size is to see if it's printed on the handlebar. This will require removing your current stem faceplate.

Best method: Use a pair of calipers to directly measure the diameter or take your bike to the local bike shop and they will be able to measure it for you.

Alternate method: Use a fabric or paper measuring tape (or print one at https://printable-ruler.net/ ) and measure the circumference of the handlebar right next to your existing stem

• A 31.8 mm handlebar will be 99.9 mm in circumference at the center.
• A 26.0 mm handlebar will be 81.7 mm in circumference at the center.
• A 25.4 mm handlebar will be 79.8 mm in circumference at the center.

Keep in mind that 25.4 and 26.0 mm are very close in size.   

If you are not able to measure your handlebar, and you know the make, model, and year of your bike, you may be able to find the handlebar size online at your frame manufacturer's website.

If you are unable to find your handlebar size online, or don't know which bike you will be using, please indicate "I don't know" in your backerkit survey.

B. How to Choose ShockStop Angle

The ShockStop is available in two different angle options: +/-6 degrees and +30 degrees. 

In general, you'll find the +30 deg stem provides a more upright, comfort-oriented fit, whereas the +/-6 deg stem puts you in a more performance-oriented riding position (standard for a typical road bike).

The +/-6 deg ShockStop can be flipped so that it's angled slightly upward (+6 deg) or slightly downward (-6 deg). The +30 deg ShockStop should only be installed in the angled upward position.

Here's some guidance on choosing your stem angle:

1) If you are replacing an existing stem and want to match it, then check to see if the angle is printed on the stem.  If the angle is close to either 6 or 30, you're all set.  If it's somewhere in between, go to #4.

If you cannot find an angle printed on the stem, continue to #2.

2) Does the angle of your existing stem look like either of the following pictures? If so, then choose +/-6 deg for your ShockStop Angle. If not, continue to #3.

3) Does the angle of your existing stem look like the one in the following picture? If so, then you should choose +30 deg for your ShockStop Angle. If not, or you still are not sure what to choose, go to #4. 

4) Do you prefer a more relaxed upright position on your bike? If so, then you should choose +30 deg for your ShockStop Angle. If you prefer a more performance oriented aerodynamic position, you should choose +/-6 deg for your ShockStop Angle.

C. How to Choose ShockStop Length

If you chose the +30 deg ShockStop, then you're all set: its length is 100 mm.

If you chose the +/-6 deg ShockStop, then you will need to choose one of 4 different length options: 

• 90 mm = 3.5 inches = 3 1/2 inches
• 100 mm = 3.9 inches = 3 15/16 inches
• 110 mm = 4.3 inches = 4 5/16 inches
• 120 mm = 4.7 inches = 4 3/4 inches

 Here's some guidance on the length selection:

1) If you are replacing an existing stem and want to match it, then start by seeing if the length is printed on the stem. Choose the length of ShockStop that most closely matches your existing stem's length. If the length is not printed on the stem then go to #2.

2) You can measure the length of your existing stem as shown in the following picture. The length is measured from the center of the handlebar to the center of the steerer tube. 

Once you determine the length of your existing stem round to the nearest 10 mm and choose the closest match.

If you are unable to measure the length of your existing stem then choose 100 mm. This is one of the most common lengths and tends to be a good fit for most people.

D. How to Choose The Right Mount

There are two different mounts available: the bike computer mount, and the utility mount:

• The Bike Computer Mount is an integrated mount that is compatible with your Garmin, Powertap/CycleOps Joule, CatEye, Mio, or Magellan computer.
• The Utility Mount puts a small section of tube in front of the stem that provides a location to mount anything you would normally put on your handlebar (bike computer, phone, light, etc.).

E. The Difference Between Drop and Flat Bars