What is a thru-axle?

A thru-axle is the axle system used to secure the front wheel on Vvolt ebikes.

It is a long axle that passes through the fork and hub, then threads into the opposite side of the fork dropout. Compared to older quick-release systems, thru-axles are generally:

• more secure
• stiffer
• better suited for ebikes with disc brakes

How to remove the front wheel

To remove the front wheel on a Vvolt ebike:

1. Use a 6 mm hex wrench
   1. Some Sirius thru-axles use an 8mm hex wrench! 
2. Insert the wrench into the non-drive side of the axle
   • This is the left side when sitting on the bike
3. Turn the axle counterclockwise to unthread it
4. Pull the axle out once it is fully unthreaded
5. Remove the wheel carefully

How to reinstall the front wheel

When reinstalling the front wheel:

1. Position the wheel so the hub is aligned with the fork dropouts
2. Make sure the disc rotor is centered between the brake pads
3. Insert the thru-axle
4. Thread it in by hand first to avoid cross-threading
5. Tighten it securely with a 6 mm hex wrench

Grease and thread care

Vvolt applies grease to the front axle threads before shipment.

When reinstalling the axle:

• Clean the threads if needed
• Apply a small amount of grease to the threads

Important:

• Do not get grease on the disc rotor
• Do not get grease on the brake pads

Where to find axle specifications

Most Vvolt thru-axles are labeled on the axle itself. 

Model-specific axle information

First-generation Sirius

The first-generation Sirius front thru-axle uses a small aluminum fixing bolt threaded into one side of the axle.

Tightening guidance:

• Tighten to about 3 Nm
• Snug only
• Do not overtighten

Fixing bolt specification: find a steel replacement bolt here

• Flanged Socket Head Screw
• M8 x 1.25 mm thread
• 20 mm length
• 17 mm flange head

Centauri 2

The Centauri 2 front axle:

• uses a 15 mm axle
• steps down to 12 mm at the threaded end
• tightens into a threaded insert/component in the dropout

That threaded component is secured in the dropout with a small grub screw.