Skip to content
Shop
How can I tell if my frame has a UDH?

Does your frame have a UDH?

UDH means Universal Derailleur Hanger: a standard derailleur hanger used on many newer thru-axle frames. It matters when you measure your frame for an A12: on a UDH frame the drive-side dropout does not need to be measured. Tell us in your message whether your frame has one.

How can I tell if my frame has a UDH?

Section titled “How can I tell if my frame has a UDH?”

The surest sign is how the derailleur hanger is fixed. If the hanger is bolted to the dropout from both sides, thread in thread, as in the picture (a bolt and a ring), your frame has a UDH. If your bike has a hanger bolted on like this, the frame is a UDH frame.

A UDH derailleur hanger taken apart: the hanger with its threaded sleeve, the ring and the bolt

The shape of the hanger, or a photo, does not tell you for certain whether it is a UDH. The way it is fixed almost always does: if the hanger comes out of the dropout like this, it is a UDH.

Still not sure?

Section titled “Still not sure?”

Check the frame specification for your model and year, or ask the frame manufacturer. You can also send us a photo of the drive-side dropout through the contact form.