Nomad 700c > 650B

[PH]

From this:

Nomad 700c by Paul, on Flickr

To this:

Nomad 650B by Paul, on Flickr

Why?  Good question, I'm not sure - to differentiate from the Mercury, curiosity, increased clearance... I considered it from the time I bought the frame last July, but the argument against was that the hubs were already built into 700c, time will tell if that becomes an issue...
Was it a good idea?  I'm undecided!  it is noticeably more comfortable off road, though just as noticeably slower on road.  Tyres have remained Almotions, 700 x 40 to 650 x 55. Much more clearance under the guards, though I still managed to clog it up on one muddy trail, though that would probably have happened to any bike with guards.
If I rebuild a 700c disc front wheel, I could run the Nomad in either configuration, the Mercury wheel would be a straight swap between them.  I might do that for fun, I only need a hub, or I might wait till I have a use for that, like if I want to do a mostly on road camping tour... or something...
   

[JohnR]

Was it a good idea?  I'm undecided!  it is noticeably more comfortable off road, though just as noticeably slower on road.  Tyres have remained Almotions, 700 x 40 to 650 x 55.

Do you attribute 650B being slower on road to the smaller wheel size or the fatter tyre?

The pre-built Mercury I bought from Thorn came with 50mm G-One Speed tyres (set up as tubelesss although the rims weren't proper tubeless-ready) which felt fine on roads but not made for serious off-roading.

[PH]

Was it a good idea?  I'm undecided!  it is noticeably more comfortable off road, though just as noticeably slower on road.  Tyres have remained Almotions, 700 x 40 to 650 x 55.

Do you attribute 650B being slower on road to the smaller wheel size or the fatter tyre?

I don't know if it's possible to separate those out, the overall diameter difference is 8mm, the width 15mm and the pressure approx 20psi.
I'm sure the gap could be closed by narrowing those differences, but then I suspect that'd take me be back to square one.  Plus the price of decent tyres!  I'm not buying any more till I've worn a few out, I think I may have enough to last this lifetime.
The difference would be quite significant if I were to use the bikes for the same purpose.  I had cause to ride the same 95km road route twice last week, mostly lanes of varying surface, undulating but not particularly hilly, very similar weather conditions, same time of day, quite roads with little traffic.  Thu on the Nomad 18.1kmh, Sun on the Mercury 20.9.  Half an hour on a touring ride makes no difference to me, and hour on a 200km ride would.
The farm track/bridleway in the above photo was ridden at about the same speed I would a country lane on any bike, I'd have ridden it on the Mercury, but more cautiously and picking the line rather than ploughing through the puddles, on the 700c Nomad somewhere between the two.  It was a lot more fun on bouncy tyres!
I don't know, I'm just musing, I haven't reached any conclusions, when I do it's be more about the rides than the stats.

[WorldTourer]

I upgraded from 26" to 650B on my Nomad Mk 2 (for which I believe the 650B size was never endorsed by Thorn, but it fit just fine if you were using the disc-brake fork) and I detected no difference in the smoothness of riding. It taught me to be sceptical of a lot of the marketing claims about 650B as an upgrade in comfort compared to the 26" standard that the industry was deadset on making obsolete. The tires and frame must have a lot more impact on the comfort of the ride than the relatively small change in wheel size. I imagine that the same must be true in going from 700C down to 650".

[PH]

The tires and frame must have a lot more impact on the comfort of the ride than the relatively small change in wheel size. I imagine that the same must be true in going from 700C down to 650".

I don't know.  when you changed wheel size. what was the overall difference? Are you suggesting there would have been little difference between a 700c x 55 wheelset and a 650B x 55 one?  Maybe so, swings and roundabouts. the Nomad won't take that size tyre in 700c, it barely takes the 40mm, so that comparison can't be made.  My Ogre did have those and the 650B configuration is probably closer to that than the 700c, but they're still considerably different.  This change hasn't drastically changed overall diameter, just width and consequently pressure, the ride feel is very different, with a similar tyre to the Mercury it felt notably stiffer, now the feel is the other way round.  Hard to describe, and of course I know such things are subjective, the Mercury feels like it's smoothing the roughness,  the Nomad doesn't feel it at all. I'm now curious to know what a 650B Mercury would feel like, though the fork isn't 650B compatible and I don't have a wheel.