I wouldn't normally bother asking, I'd just take a chance, but I've got an ongoing neck/wrist/hand problem, so I wondered what sort of a mixture it is of road, grass and stone track.
Is it something like the Mid Wales Merida Marathons ? If so, I'll give it a go.

There's not much detail on the routes on the website.
How far in is the split ? It sounds like it's near the end of the 71km route.

Where is The Gap ? I've looked on the OS map and can't find it.

My mate lives near Merthyr and rides about the Beacons all the time on his rigid… that said he's made of 853 steel tubing.

I'd prefer not to ride rigid around that way, personally – but a hardtail is sufficient.

You'll be fine.

I wouldn't fancy The Gap itself on a full rigid but over the lip and down through the rocks is only a hundred yards or so. The rest of it is eminently doable on full rigid.

I wouldn't fancy The Gap itself on a full rigid but over the lip and down through the rocks is only a hundred yards or so.

The route normaly goes up the gap.

not ridden the route you are asking about but I'm fairly confident in saying that ALL routes are doable on a full rigid..

Well, yes, normally that would be my attitude, but I'm a bit delicate at the moment when it comes to long distances over rough ground.
Getting off to walk a couple of hundred yards of rocks is no problem, but I don't fancy mile after mile of this…

fully rigid

and

ongoing neck/wrist/hand problem

… !

But yeah you'll be fine, might even be an advantage if there's as much road/fire track as previous years! (not complaining btw, I like the old course)

Someone last year did it on a 20" shopper bike…. but which route I don't know – I was on a hardtail and this year would probably go for the plush FS option.

I think if you're going up the gap you'll be alright on a rigid, but I seem to remember the other side isn't the smoothest trail I have ever ridden up so you'll prolly take a bit of a battering on the way down.

[anti-niche-question]Why do you have to go with the rigid? If you have neck etc issues, what's the point when you have some perfectly good forks to stick on the front?[/anti-niche-question]

If you were going down The Gap I'd say definitely think about squishyforks.

Rigid no trouble … just watch out for the mincers at the top of the rocky chute on their 6" full sussers, they'll slow you down 😉

OK, some background information.

Possible Carpal Tunnel Syndrome, trapped nerve in the neck, or both.
Waiting for the full diagnosis after having the tests. Currently on Naproxen, a sort of stronger version of Ibuprofen.

3 hours/55km last Sunday = no problem.
5.5 hours/67km the Sunday before after forgetting to take my morning tablet = neck pain.

Bikes available;
Lynskey Ti 29er rigid.
Gary Fisher 29er hardtail.

I much prefer riding the Lynskey, it just feels so much lighter and faster than the Gary Fisher. Trouble is, it's a longer head tube and the only forks I've got that fit it are carbon rigids.

I'm riding 90km at SPAMBiking September Blast the following weekend, where the Lynskey is the ideal compromise between an MTB and a CX bike.

It takes me a week or more to recover from a big ride, so maybe I should just plod round slowly and enjoy the scenery on the heavy and slow (in relative terms) Gary Fisher and save myself for Salisbury Plain.