I was running an 80mm front rim from the off. the speedway 80mm uma rim is approx 800g, close to a gordo and not much more than the 50mm. It is single walled. fatback (aka Greg at Speedway Cycles) has got a proper website together now, looks like as a result of the big boys jumping in) but it does mean some of his rather nice components are more easily accessible to those not ‘in the know’ as it would appear you can spend a lot of time working out what you can and can’t do and on what!
Anyway, I second SinglespeedStu’s comment, an 80mm rim stabilises the tyre at low pressure, gives a nicer ride and more grip.
I rode Trans Provence this year on the half fat Jones and to answer another well worn question, they are not more draggy off road. On the contrary. They are at v. Low pressure on road though, so best to stop and put a bit of extra pressure in them. They are terrific in single track offering ooodles of grip and on loose gravelly stuff.
One thing I did notice was that as we were riding so high ( starting at 500m or so and ascending to between 1200m to 1700m then descending, there was a very noticeable change in my tyre pressure, I think as it is already so low.
On the first day I set it as normal for big rocks at 5psi at the base and when I descended it felt like a front end pogo stick on the rocks! I reset the pressure at the top from then on but it ws amazing how much different the front felt at the end of a descent,
I had loads of rim strikes on my Speedways but never once got a pinch flat/ damaged rim or out of true wheel.
Shows the benefits of a 135mm dish less front and very wide rim.
Interestingly the rotating weight doesn’t seem to be a problem either, in fact at speed it really helps with rolling over stuff with rigid forks, but the the SC’s are always an option.
Geat fun!
I’ve been talking to Greg at Fatback about a Fatback Ti for a while but haven’t taken the plunge. The way things are the only way that could happen is if I let the JJ go. I can’t decide whether that’s a trade I’m willing to make…