• May 18, 2022

How Do I Know What Size Axle I Need For My Bike?

How do I know what size axle I need for my bike? Measure the straight length of your axle shaft. Do not include the axle head or tapered spacer, if there is one. Axle length is not the same as hub length. A bike with a 12×142 hub standard will have a significantly longer axle since it will have to go through the frame on both sides of the 142mm wide hub.

What size are bike frame bolts?

The most common sizes of allen screws for bikes are 4, 5, and 6mm. There's even a common bike tool that will fit in all three. In my experience, most racks use 5mm screws, but some do use 4 or 6mm screws.

What is 15mm thru axle?

15mm thru axle uses a different connection on the fork where the axle of the wheel allows a 15mm bolt to go through it. Same concept for a 20mm thru axle. Some wheel manufacturers have adapters that allow you to use the same wheel with the different fork hub standards by swapping out the axle ends.

What bolts are used on a bike?

Standard thread dimensions used with bicycles

ISO dimension Common use Allen
M6 x 1 mm brake caliper retaining bolt, anchor bolt for brake and shifter cables, derailleur mounting bolts, brake and shifter lever mounting, stem bolts, saddle bolts, seat post bolts 5 mm
M8 x 1.25 mm quill stem bolt, seat post bolts 6 mm

What are M8 screws?

The defined diameter of metric bolts is actually slightly larger than the actual diameter of the bolt shaft. So an M8 bolt would have a shaft diameter that's slightly under 8mm which means that the bolt should fit through an 8mm hole.


Related guide for How Do I Know What Size Axle I Need For My Bike?


How do you measure bolt thread size?

To measure the diameter of screws and bolts, you measure the distance from the outer thread on one side to the outer thread on the other side. This is called the major diameter and will usually be the proper size of the bolt.


Can I use quick release to thru axle?

The best and easiest solution is to swap out your quick release fork for a thru axle fork. In most cases, you will also need a new front hub that is compatible with thru axles. 15 mm is the most common diameter for front thru axles. There are also adapters that allow you to use a thru axle hub in a quick release fork.


Should you grease thru axles?

Although it is not required, it is recommended that you apply a light amount of grease to your Mountain Bike axles. You can apply it to the threads, and also on the base of the axles themselves. This not only makes them easier to install and remove, it also helps prevent rust and corrosion.


Does my bike have a bolt axle?

Your bike has a thru axle if the “drop out” is a hole, rather than a U-shaped dropout. This provides added security because even if the lever on the end of the thru axle flips open, it is still threaded into the frame, holding your wheel on. If you have a 12mm threaded piece, then you have a thru axle.


How do you measure a rear axle?


What is a rear thru axle?

A thru-axle (TA) is a wheel attachment system that secures a wheel on a hub between a pair of dropouts on a bicycle frame or fork. The thru-axle threads directly through the fork/frame holes and into the wheel hub, which makes the wheel secure from detaching.


How do you install a rear axle?


What is a Maxle axle?

Genuine replacement axles for Rockshox forks. The Maxle Stealth is a bolt up axle that does away with the quick release lever for the lightest and cleanest possible set up. The Maxle DH is a tooled axle for 20x110mm spacing.


Do I need thru axle adapter?

You'll need an adaptor in order to fit a thru axle bike to a wheel-on trainer. You usually have to buy the adaptor separately. Most direct drive trainers now come with whatever's necessary to use it with a thru axle bike.


How do I know if I have an axle or quick release?


What is the thread size?

The thread size measures the thread's thickness. If another weight is given for thread (like ounces), it refers to the amount of thread on the spool. Thread tends to get stronger as it gets heavier. The tension on your sewing machine will need adjusting when you switch thread weights.


What thread is a bicycle spoke?

According to the Park Tool website, the typical 2mm spoke has a 2.2mmx56TPI thread. This converts to a 2.2mmx0. 45mm metric thread pitch.


Are M8 and 5/16 the same?

Well, quick answer is no. They are not the same and they are not interchangeable, although they can work under certain circumstances. The most important part is understanding the meaning of M8 and 5/16 to refer to the size of a metric screw or bolt, so then we can see why they aren't the same thing!


Is M8 a 10mm?

M8 (8mm) Thread Size (T) 5.4mm Head Length (H) DIN 933 Manufacturing Standard. 10mm Length (L)


Which is bigger M6 or M8?

The size of a metric screw or bolt is specified as diameter, pitch and length, in millimeters (millimeters is abbreviated "mm").

Table 3.

Metric Closest Inch
M6-1.0 1/4-28 (Larger)
M7-1.0 1/4-28 (Smaller)
M8-1.25 5/16-18 (Smaller)
M10-1.5 3/8-16 (Smaller)

How do I determine thread size?


What size is M8 thread?

Tap size Basic major dia (mm) Basic major dia (inch)
M8 x 1.25 8mm .3150
M8 x 1 8mm .3150
M10 x 1.5 10mm .3937
M10 x 1.25 10mm .3937

What is bolt thread size?

Thread sizes are given in nominal sizes, not in the actual measurement. The exact measurement is slightly below the named or nominal size. For example, a 6mm bolt may measure 5.8mm or 5.9mm, but it is called 6mm bolt. It is also common to use “M” before the bolt size, such as M6 for a 6mm bolt.


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