The ShockStop handlebar clamp is 31.8 mm which is compatible with many modern bikes, without the need for shims. However, some bicycles have different size handlebars which may require the use of shims to fit properly into the ShockStop handlebar clamp. We 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. However, other handlebar shim sizes may be available at your local bike shop. 
- Note that some mountain bikes have “over-sized” 35 mm handlebars which are not compatible with the 31.8mm clamp and would need to be replaced with a 31.8 mm handlebar in order to be compatible with the ShockStop Stem.

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. 

 

If you can't find the printed size, there are a couple ways you can measure your handlebar: 

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.

Different bikes sometimes have different seatpost diameters. The ShockStop Seatpost is 27.2mm in diameter, so if your bike's seatpost is larger, you'll need a shim to adapt our seatpost to your bike's frame. Don't worry though, the shims are super-lightweight and essentially invisible once installed.

Not sure what size seatpost you have currently? There are a couple different ways to find out.

350mm is our standard size, but we added the 280, 400, 450mm to allow for a wider range of fits (400 & 450 only available for the ShockStop Endurance Seatpost). Measure your current seatpost from the clamp collar to the saddle rail:

• If that distance is less than 205mm, you can use the 280mm suspension seatpost.

• If it is between 205mm and 250/275mm (depending on diameter) order the 350mm size.

• If it is between 250 (larger diameters than 27.2) and 300mm order the 400mm size.

• If it is between 300 (larger diameters than 27.2) and 350mm order the 450mm size.

There are two different optional mounts available: the Computer Mount, and the Utility Mount: 

The Computer Mount is an integrated mount that is compatible with your Garmin, Powertap/CycleOps Joule, CatEye, Mio/Magellan, or Wahoo bicycle computer (for options not in drop down, please email us at support@redshiftsports.com).

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.). 

 

Steerer Tube Diameter  
 

The ShockStop is available in two different Steer Clamp options: 1-1/8” and the new 1-1/4”

The 1-1/8in ShockStop stem fits standard 1-1/8in (28.6mm) steerer tubes which is the size used by most modern bikes. With the introduction of our new 1-1/4” version the Shockstop can now be used on popular brands such as Giant and Canyon bikes (please check your exact model specs to be certain).

The easiest way to determine your steerer tube size is to 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.

If you don’t have easy access to either, a shop or a set of calipers you can check your manufacturers website. Most of the time a manufacturer will list this under their specifications in the Frame/Fork section. Make sure you are looking at the correct model year as these sizes can change year to year.

Alternate method: Use a fabric or paper measuring tape (or print one at https://printable-ruler.net/ ) and measure the circumference of the steerer tube. You will need to remove the compression cap and loosen the two pinch bolts to get access to your steerer tube so be sure you are comfortable in doing so and then reassembling properly. 

• A 1 1/4”(31.8 mm) steerer clamp will be 99.9 mm in circumference at the center.
• A 1 1/8” (28.6mm) steerer clamp will be 89.9 mm in circumference at the center.
• A 1” (25.4 mm) steerer clamp will be 79.8 mm in circumference at the center.

Stem Angle 

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

In general, you'll find the +30 deg stem provides a more upright, comfort-oriented fit, whereas the +6 and +/-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. 

 

Stem Length 

If you chose the +30 deg ShockStop, you can choose either an 80mm or 100mm length option.  
 

If you chose the +6 degree , you can choose either a 55mm or 70mm length:

- 55mm = 2.2 inches 
- 70mm = 2.75 inches 

If you chose the +/-6 deg ShockStop, then you can choose one of 5 different length options: 
- 55mm = 2.1 inches

- 70mm = 2.75 inches

- 80mm = 3.2 inches 
- 90 mm = 3.5 inches
- 100 mm = 3.9 inches
- 110 mm = 4.3 inches
- 120 mm = 4.7 inches 

1-1/4 inch steerer stems are not yet available in 55 and 70mm lengths but you can signup here to be notified.

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. 

 

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

4) If you are unable to measure the length of your existing stem then choose 90 mm. This is one of the most common lengths and tends to be a good fit for most people.