Tag Archives: A23

Q: What is the outside and inside dimensions of the No Tubes Alpha please? I need a wider-than-open-pro 28h rim.

A: I just measured some rims for you:

Inside/outside widths

Mavic Open Pro 14.5mm / 19.7mm
NoTubes Alpha 340 17.1mm / 20.2mm
Velocity A23 17.8mm / 22.7mm

Just a quick post about converting the popular Velocity A23 rims to run them tubeless for cyclocross or road since we've been experimenting today. The A23 has a smooth curved inside wall and converts pretty easily to tubeless with the correct products. All products mentioned below are available in our shop.

Cyclocross tyres

We fitted a Hutchinson Piranha (tubeless ready) with just the NoTubes yellow tape and a 44mm Universal valve stem. The tyre was pretty tight and needed careful use (not damaging the yellow tape) of tyre levers to get the tyre on. It inlated immediately using a standard track pump.

Then we tried a standard Maxxis Raze 700x33C. It went on very easily, too easily in fact with just the yellow tape, and burped easily. We fitted the Cyclocross rimstrip and it inflated a lot easier, either with some vigorous pumping from a normal track pump, or very easily with a compressor. In use it may need a layer of 17mm Velox tape under the rimstrip; we'll find out soon and add to this page.

Road Tubeless

To be confirmed, but since the Hutchinson cyclocross tyre inflated easily, the road tubeless tyres should too using just the yellow tape and 44mm valve stem. You'll need 2 layers of yellow tape to withstand the high pressure or it may pop through the spoke holes.

Tyre pressure warning

We've said this before but it's worth emphasising. Do not try and convert standard tyres to road tubeless; only use proper road tubeless tyres. If you want to run your cyclocross tyres over 40psi do not convert standard tyres. Normal tyres will be at risk of popping off the rim at over 40 psi. Over 50psi it's almost guaranteed to fail. The bead on road tubeless tyres is much stronger than on a standard kevlar tyre.