By my understanding you measure from the top of the crown race to the axle/ middle of the drop outs.

My new rigids measure 445mm, but for a 29er the manufacturer describes it as being 470mm.

Wrong description from the seller?

It’s a carbon Syncros fork.

It depends on what range of suspension the frame is designed for really. I run 440mm forks with a 29″ wheel on a 26″ frame and there is loads of clearance so that isn’t an issue but if your frame is designed for say 100mm suspension then you might find they give you a steeper head angle than you’ll want.

Can you put a 29er wheel in it, if yes then it is a 29er fork, if no it isn’t. whether it is the right fork for you, Live and learn.

Definitely a 26″ fork. 445mm a-c with a 38mm offset.

Mrmo I have a couple of pairs of 26″ rigid forks both of which I can fit a 29″ wheel in.

You can fit a 29er wheel/tyre into a 420mm a-c fork.

Generally, 440mm are considered to be 26″ forks and 470mm are considered 29er forks.

But, a long travel 26″ frame would better suit a 470mm fork while a designed-for-rigid 29er frame might work best with a 440mm fork. (All assuming disk-only, obviously.)

But, if buying online I’d assume “29er fork” meant 470mm a-c.

http://www.syncros.com/syncros/ca/en/products/2348090135/fork-syncros-xr10-carbon-rigid-29-black-matt/

470mm according to that?

toppers3933, then toppers you have a short 29er fork or a long 26er fork. Different frames suit different forks.

Start with a bike designed for a 150mm sus fork and then think about a frame designed for 80mm sus forks. You may not be surprised to learn than the “correct” rigid fork will be a different length.

Nothing is black and white and assuming anything is always a dangerous game, find out how long a rigid fork your bike needs, don’t assume that something labeled 29/26 is actually suitable for you.

I have a 26″ fork @440mm which will take a 29er wheel quite happily but it’s still not a 29er fork as set out by Syncros.

i thought the Syncros 29er rigid fork was 480mm ac length?

review

No that’s an older model.

Newest model is 470mm a-c with 45 mm offset.

looks like you have a 26″ by mistake. Length is listed here…
http://www.evanscycles.com/products/syncros/xr10-carbon-rigid-26-mountain-bike-fork-ec050310#features

I have a 26r steel on-one fork that now has a 29r wheel comfortably in it on a 456 frame. A quick garden pedal suggests this will be about right for my 69r project.

Back ot a to c is about 440mm