Which pannier rack for gravel bike

A topeak 29er with the mount for their sliding quicktrax top-bags will give you the best of both worlds.

Tortec Ultralight is a reasonable budget choice. Or Blackburn MTN.

https://www.tredz.co.uk/.Tortec-Tour-Ultralite-Rear-Pannier-Rack_3043.htm

Thanks. Excuse my ignorance but how does the rack attach to the eyelet which is located on the centre of the bridge piece across the seat stay? All the images show the racks attaching to eyelets on either side of the chain stays.

The top supports usually bolt onto eyelets near the top of the seatstay. If your bike doesn't have these you can change the seat clamp for one with eyelets in so that the rack is held with 4 bolts (2 top and 2 bottom).

Some racks can be fixed at a single point to the seatstay bridge. I've used this on past bikes and found 4 point mounting with eyelets in the seat clamp (if there are none on the frame) to be more solid.

Link to seat clamp of the type mentioned:

https://www.tredz.co.uk/.M-Part-Seat-Clamp-Mount-31-8mm_34111.htm

Or with more sizes available:

https://www.sjscycles.co.uk/seat-posts/286-passport-seat-clamp-with-rack-mount/

Picture of well used Tortec rack fitted to seat clamp eyelets and even older Blackburn MTN rack fitted to frame eyelets behind.

I have one of those Tortec racks.  If you can solve your mounting issue it's nice and sturdy.  I did find the anodising was prone to wear on the verticals where the pannier mounting system rubbed.  An inner tube wrap / chainstay protection type wrap would stop that.  

A word of warning on installation. 

The blanking bolts installed in many bikes' threaded rack holes from the factory are short and the rack feet/legs are thick.  You may need to order / find some longer bolts.  

Thanks for the help!! I have a rack on my hybrid but to get it on the gravel bike I’d have to very slightly stretch the legs to fit over the chain stays where the eyelets are which would save me some cash but is there any downsides to this?

Some racks come with multiple mounting options/attachments, including single bridge.

I sometimes use a Giant Rack-It rear rack on my Sonder Broken Road. It came as standard equipment on my wife’s Giant Toughroad but is a universal fit and has a single bridge mount.

Both those racks in the picture up there have been slightly stretched/bent to fit using spanners, vice or just pull apart by hand. To me this is a normal part of rack fitting. The green bike is boost hubs and needed longer bolts so the rack had to be pulled apart a fair bit and then feet bent vertical. It was previously on my old audax type road bike the had narrow 130mm axle hubs. Just adjust to fit.

Thanks slowol 👍🏻

What kind of tyre clearance should you allow for between the rack and tyre?

A little finger thickness would seem like plenty. Less probably OK. Too much space is more of an aesthetic issue than practical.

The gap between the rear rack and tyre on my gravel bike needed to be narrow as I didn't want the rack to interfere with the saddle bag.

I was able to position the rack flush with the top of the Win Wing.

If it's a gravel bike that is going off road, black painted pannier rack will look tatty pretty quick, mine is wearing through where the bag mounts on