Hi All!
By chance, I just covered this very question in an extended PM. Rather than start from scratch, I'll share it here as I think it answers most of the questions. Remember, I owned a Sherpa Mk2 and now have a Nomad Mk2. The Sherpa and Raven-series have been redesigned since I owned my Sherpa Mk2 (purchased in September 2011)...my comments are based on my own ownership experience with both bikes for my primary use -- expedition touring with loads hovering around 50kg and (secondarily) very long 200-400km day rides in mountainous terrain with a load of about 10kg.
How to speed up a Nomad Mk2?The short answer... The Nomad is a purpose-built expedition touring bike geared toward carrying heavy loads in extreme conditions. It has a heavy frame and (usually is equipped with) heavy wheels and tires, and it won't accelerate quickly. When weighed against its cargo capacity and durability, the slow acceleration isn't noticeable -- fully loaded, it will weigh a lot anyway and the extra frame weight is offset by extreme durability.
Unladen, it will feel more ponderous than bikes oriented toward lighter-duty use. This is no surprise, given its mission.
Changing to lighter rims, tubes, and tires to reduce rotating weight will make the bike feel more lively, but at the expense of ride comfort. It is generally impractical to change rims, but tires and tubes are easy. However, the heavy frame is less compliant than, say, a Sherpa and in my experience depends more on wide, low-pressure tires for ride comfort. I like and use 2.0 Schwalbe Duremes as an all-'round tire, and have happily ridden the bike a couple-hundred kms at a time, provided the tire pressures are appropriate for unladen use. As for making the bike "faster" (increasing speed/acceleration), you might well try a narrower, lighter tire and tube, but I would expect ride comfort to suffer. The heavy bike won't
accelerate as fast as a lighter one, but
once up to speed, it should hum along pretty well. That it doesn't, makes me fear something may be amiss.
The long answer, via PM redux, with a Sherpa Mk2 comparo...- - - - - -
...the Nomad looks the more likely candidate. I want something that is suitable for a long tour; that can carry a load and is very comfortable. I intend to ride on a mixture of surfaces including tarmac, grit, dirt and forest trail so need a bit of a jack of all trades.
I think the Nomad will do that for you, but the "very comfortable" part might require use of larger, lower-pressure tires to accomplish in my experience. Let me try to explain by one real-world example:
I rode Sherpa with 2.0 Duremes pumped up F/R to 45/55psi (3.1-3.8bar) on a 125mi/200km round trip day ride to Mt. June in Oregon's Calapooya mountains. This included about 17mi/27km of singletrack and lots of rough gravel. I returned home a little tired, but not beat-up from it. The bike rode much like my conventional rando-bike/tourer, but more "heavy-duty".
In contrast, I did a 110mi/177km ride on the Nomad over the Coast Range to Alsea and back, with about a quarter of the ride on logging roads
using the same amount of air in the same-size tires (2.0 Duremes) and felt like I had caught the 'flu on my return. Even my *skin* ached from the road shock and vibration. The problem? Just too much tire pressure for the much sturdier, less-compliant frame of the Nomad when riding unladen. The same pressure in the same tires that was fine on Sherpa resulted in a jackhammer ride on the Nomad. The excessive pressure was entirely my fault, an oversight 'cos I forgot to lower it for unladen riding after experimenting with fully-loaded pressures.
Lowering the 2.0 Duremes' pressure to F/R of 27/37psi (1.9-2.55bar) transformed the bike and made the ride lovely when unladen. Of course, when riding with a load, I'll add pressure to compensate; pressures this low would be unsuitable for 50kg+ in cargo added to the weight of the bike and myself.
When I was struggling with the
loaded-shimmy problem on Sherpa I briefly fitted the 1.5 road slicks from the tandem, and it transformed the
unladen Sherpa in a positive way. At 85psi, the bike was still comfortable, but handled and accelerated like a fighter plane in comparison to when the 2.0 Duremes were fitted (the smaller tires also altered the effective trail and therefore the handling as well). I could easily see myself using it for 400km day rides with relative ease, as I do my rando bike. Those same 1.5 tires on the Nomad...well, I haven't tried them, but I have some doubts it would be as comfortable as with my aired-down 2.0 Duremes. I think the 1.5s might well result in a jarring, vibration-filled ride. I really should try them just to see. I could well be wrong! Perhaps with appropriate tire pressures, they would do fine and the Nomad would
feel similarly "fast" whether it was or not in actuality (remember, narrower tires require greater pressures resulting in more vibration that we often interpret as "faster" when, in fact, rolling resistance may indeed be greater compared to a fatter, softer tire).
I am intrigued by your observation that the Nomad has a 'less resilient' frame. Did you mean that it has less 'flex' or 'give' than the Sherpa or I am misunderstanding you completely.
You're spot-on in your interpretation. In the brochure, Andy Blance says the Nomad has a frame weighing around 3kg. That extra weight comes from such things as thicker tube walls, larger 19mm seatstays on the bigger frames like mine, and the tubing is drawn straight, rather than conical.
Looking at the Sherpa next to the Nomad was a study in contrasts:
The Sherpa almost looked like two bikes joined together: Oversize head, top, and downtubes, tapering to a standard-diameter seat tube and 'stays with a touring bike-like fork. With my drop 'bars and little slope to the top tube, it could have been mistaken for a road-touring bike. It rode like one, too.
In contrast, the Nomad looks all-of-a-piece, with the seat tube, stays, and even the fork of commensurate size with the nontapered top- and downtubes. It appears more balanced overall, but all toward the heavier-duty end of things, and you can see more of a mountainbike influence in the greater slope to its top tube and a frame geometry that allows similar handling with a sus-fork if desired. The biplane fork crown bespeaks some additional lateral sturdiness as well.
Here's an analogy from my time in the car world: In ride quality, Sherpa was a WRC rally car, capable of speed on any surface. The Nomad is a Kamaz Dakar rally-raid truck, with astonishing speed and handling
for the amount of weight it can carry.
Then, too, there is tube wall thickness. It appears Sherpa Mk2 had tube wall thicknesses of .9/.6/.9mm on those conical tubes. In contrast, it appears the Nomad might have 1.0/.7/1.0 on its straight tubes (large diameter their entire length), so yes --
the Nomad's frame is less resilient and "stiffer" than that of my Sherpa, befitting its purpose and intended use as an expedition tourer. Since the RavenTour was essentially the same frame as the Sherpa Mk2 (differing in drivetrain, of course), I think my Sherpa comments would generally apply to it as well. Of course, now we have the Sherpa M3 and the new Thorn Raven, and both are different bikes than before, spaced a bit farther away from the "heavy-lifting" Nomad and biased more toward lighter service and general use than before (and certainly less load capacity, thanks to tube diameters keyed to frame size). Looking at the size-specific tube diameters, I think the new models are likely more suited as capable all-'rounders than before.
My last post on the "Danneaux's Sherpa" gallery topic pretty well sums up the differences between the two bikes and puts the Nomad into perspective in this regard (
http://www.thorncycles.co.uk/forums/index.php?topic=3896.msg22473#msg22473 ):
I can already tell you it [Nomad Mk2] is much like Sherpa in all the positive ways; the bikes definitely share the same DNA, and the Nomad is like the Sherpa but "more" -- a good all-rounder, but also more robust and heavy-duty as befits a true Expedition Tourer with enormous cargo capacity. At the same time, it maintains lively and accurate low-speed steering with or without a load, and is entirely pleasant to ride in either state, though biased toward loaded touring. The Nomad's frame is a bit heavier, of course (a difference of no importance when carrying a full touring load) but the light steering belies the weight and once up to speed, it is easy to maintain progress at the same rate as on Sherpa. I believe the Nomad Mk2 relies more on tires to provide comfort and suspension, and it does well on both counts, providing a smooth and confident ride regardless of terrain. I am running the same tires and rims (albeit in 32-hole rather than 36 as on Sherpa) and have the identical position/fit on the new bike, so some direct comparisons and contrasts can be made between the bikes and the gearing (derailleur vs. Rohloff).
Both bikes make good all-'rounders; the Nomad simply is biased firmly toward the "Expedition touring" end of the spectrum, just as it says on the tin. Here's a little pictogram and some more words to help illustrate the difference:
http://www.thorncycles.co.uk/forums/index.php?topic=4713.msg23329#msg23329Incidentally what would be your choice for an 'all/general purpose' tyre on your Nomad?
At present, it would be the 26x2.0 Schwalbe Dureme, though it bugs me terribly the tread cap "wanders" as much as it does. With the extended front mudguard, I now don't see it! Hey! Problem solved! I tried a Continental 26x2.0 Cruise Contact. Weight was about half-again more (!) than the Dureme, and the tread cap wandered just as much, so I sent them back. Because of the shorter-wider contact patch, the wider tires can be run at lower pressures without a commensurate increase in rolling resistance. So yes, I would suggest a 2.0 tire for the Nomad for use as an all-'rounder that also offers comfort. I have for years preferred road slicks even for off-road (less mud collected, less water thrown, and easier to clean), but chose the Duremes over the Supremes 'cos the tread is shallow and does give a better mechanical "lock" with a dirt surface or on the nibbled edges of pavement than the slicker Supreme. Rolling resistance between the slick Supreme and the shallow-treaded Dureme is about the same, thanks to what amounts to an interlocking center on the Dureme for road use.
I think both the Dureme and the nearly identical-but-for-tread Supreme are tough tires...but both have vulnerable sidewalls that can be torn by rocks, witness Forum member Richie Thornger's recent experience in Iraq. Of course, it is this same supple sidewall that gives such low rolling resistance in part and good ride comfort.
In summation, I think you'll find the Nomad will meet your general needs fine --
perfectly if you'll be expedition-touring -- and
pretty well for anything else if you reduce pressures and use wider tires. The heavier, thicker-walled less-compliant frame makes it more dependent on tire pressure/width for comfort so far in my experience. Do that, and you'll be okay. It is heavy, though (mine weighs 46lbs/20.9kg, same as the tandem), so it takes a bit longer to get up to speed than the rando bike, but it cruises just fine once there.
If you'll be just riding unladen around most of the time and touring occasionally and then with less-than-expedition loads, I think a "lighter" Thorn would suit your needs much better, and would suggest the new Thorn Raven if you prefer a Rohloff drivetrain or the new Mk3 Sherpa if you prefer derailleurs; the latter is a tremendous bargain in an all-'round bicycle and is among the best-suited for general use with touring in my opinion if cost is a factor.
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Hope this helps answer your speed question, Rocky, as well as Zero's on how the Nomad Mk2 compares to the Sherpa Mk2. Apart from decreasing the rotating weight of the wheels through lighter tubes and tires, I would suggest also looking for something amiss. Despite carefully checking when off the bike, sometimes a brake can move into a position where it drags while riding, or perhaps the rear hub q/r is too tight. I have a nagging suspicion something is amiss for your Nomad to be so much slower than your 700x35c Surly. Can you tell us which Marathon tires you're using? If they are the Marathon Plus, I've found those to feel pretty slow compared to other Marathons in the Schwalbe line.
Please let us know how you get along with the 1.6 Supremes.
Best,
Dan.
