How To Measure Your Bike For Pitlocks

How do I measure my bike for Pitlock anti-theft skewers?

This can feel a little intimidating at first, but it’s actually very easy. Depending on the level of security you desire, you’ll need to measure your wheels, your seat tube and seat collar, and/or your headset. If your bike has thru axles you’d like to replace, please see our specific guide for measuring your bike for locking thru axles. Otherwise, follow these instructions:

  1. To measure your wheel skewers, first remove the existing 5mm “quick-release” skewers from the wheels of your bike. With these uninstalled, measure the distance between the outer edges of the dropouts, shown here:

    Once you have this measurement, see the table below and find what range this measurement falls between in column “(d)”. The corresponding column “(a)” is the size you will need to order.

    Tips for measuring:

    1. Be sure to measure both the front and the rear dropouts, as they are different widths. There isn’t a “standard” length, but front wheel hubs are commonly 105mm and rear wheel hubs are commonly 135mm. The Pitlock skewers you purchase will need to be this length (the width of the wheel), plus the width of the each side of the dropout.
    2. If you do not have a ruler to measure with, we recommend using this printable ruler. Do not scale the image, print it at 100%. If you do not have a printer or a ruler, please contact us and we will mail you a printed copy of this ruler for free.
    3. You do not need to account for the 10mm of skewer that the Pitlock locking mechanism will require – we already do. The lengths advertised on our site are the “installations lengths”, not the total lengths – which are 10mm longer than the lengths shown. Column “(e)” in the table below shows the total length of each skewer, as opposed to the installation length (column “(a)”)

  2. To measure for a seat skewer, you’ll first need to determine if your existing seat clamp (seat collar) is suitable for Pitlock skewers. To do so, please see our FAQ on seat clamp compatibility for Pitlock skewers. Once you’ve determined that, measure the length of your existing skewer for your seat clamp (do not include the handle of the skewer in your measurement.) Alternatively, measure the distance between the clamping faces on your seat collar to ensure that you order a long enough seatpost skewer. If you’re replacing your seat collar with a Pitlock seat clamp, then please order the standard 33mm length seat skewer. This size will fit all Pitlock seatpost clamps.

  3. To measure for a locking topcap, remove your existing top cap by unscrewing the allen head bolt in the center. You should see something like this image. Measure either the inside diameter of the stem (shown in green), or outside diameter of the steerer (shown in red.)

    You should get a measurement of either 1″, 1-1/8″ or 1-1/4″. Older bicycles are likely to sport a 1″ steerer. The modern standard size is 1-1/8″. Some newer mountain bikes will have a 1-1/4″ steerer, though it is still fairly uncommon.

Are Pitlock seat skewers compatible with my current seat collar?

If your existing seat clamp (seat collar) has flat, parallel clamping surfaces on both sides, and the hole is at least 5mm in diameter, then yes – your existing seat clamp is compatible.

However, if your clamp does not have the two flush surfaces that Pitlock skewers require, the integrity of your locking seat skewer may be compromised without a Pitlock seat collar. This is commonly the case if your existing clamp/collar has an integrated quick-release skewer, uses a proprietary bolt, or has a hole that is less than 5mm in diameter.

To purchase a new seat clamp, measure the diameter of the seat tube itself. The sizes of Pitlock seatclamps (for exampple, 31.8mm) will refer to this measurement:

How do I measure my bike for Pitlock locking thru axles?

There are still very few standards between through-axle manufacturers, and determining the size you need can be difficult if you are unfamiliar with the detailed construction of your bike. Please see our thru-axle measurement guide for specific instructions.

How long are Pitlock skewers?

All Pitlock skewers are approximately 10mm longer than the length shown, to account for the space required for the locking mechanism. All Pitlock wheel skewers are threaded for 30mm, except for the 240mm skewer (which is fully threaded its entire length.) For example, the 155mm “standard” rear skewer is 165mm long total, and is threaded from 135mm to 165mm.

All seat skewers (skewers that are 60mm and shorter) are also 10mm longer than the length shown, but are only threaded for 25mm. For example, the 33mm “standard” seat skewer is 43mm long total, and is threaded from 18mm to 43mm.

What is the minimum installation length for each Pitlock skewer?

Here is a table showing the installation installation range for each Pitlock skewer. Column “(a)” is the length shown on the product pages. As long as the length of the skewer you’re replacing falls somewhere within the range of column “(d)”, the Pitlock skewer equivalent will fit your bicycle. Column “(e)” is the total length of the skewer; the locking mechanism requires 10mm of the skewer length to function properly. For information on thru axles, please see our thru axle guide.

Displayed Length (a) Skewer Type (b) Standard? (c) Replaces Skewers (d) Total Length (e)
120mm Wheel Yes 100mm to 120mm 130mm
130mm Wheel No 110mm to 130mm 140mm
155mm Wheel Yes 135mm to 155mm 165mm
170mm Wheel No 150mm to 170mm 180mm
240mm Wheel No Up to 240mm 250mm
23mm Seat No 8mm to 23mm 33mm
33mm Seat Yes 18mm to 33mm 43mm
45mm Seat No 30mm to 45mm 55mm
60mm Seat No 45mm to 60mm 70mm