Donnelly MSO 650B X 50mm: At The Finish

Donnelly MSO 650B X 50mm: At The Finish- by Grannygear

Editor’s Note: Please click here for the “Checkpoint” post previous to this final verdict on the MSO tires.

I get sea sick.  I just wanted to toss that out there (no pun intended), so when I had an offer to stay on a friend’s sailboat for the weekend and do some riding on Santa Catalina Island, an island 26 miles off the Southern California Coast, I decided to take the 45 minute crossing on the high speed catamaran (Catalina Express) over to see them rather than the slow and wobbly 4 hours it takes to get there on their sailboat.  That also let me bring a bike, basically rolling it on board the ‘ferry’, along with a bag or two.

But what bike should I bring?  Last time I took a Plus bike hardtail and that was too slow.  The roads there are not very rough, but the climbs seem never ending and are often quite steep.  I recall thinking that this would be a great gravel bike destination.  And so it was settled.  I decided to keep the MSOs on the Lynskey even though I would be paying a bit of a weight penalty with all that climbing.  However, in trade I would be bombproof on any rough parts, would be crushing the fast downhills, and overall comfort would be as good as it gets.

Honestly I could not have made a better choice.  In the dirt, I did not notice the rolling weight really, and the comfort and capabilities of the 50mm casing were so reassuring that it reaffirmed how valid this set up would be for any backcountry use like bikepacking, etc.

At the end of the day, I could have run my standard 700×42 Resolutes and been fine, but with no pavement except one small part (and that was horrible pavement actually), I gained more than I lost with the 650Bx50 setup.

Now that this is a wrap, what are my specific thoughts on this tire and the 650B category et al?  I am glad you asked.
First, the Donnelly MSO Xplor 650Bx50 Good and the Less Than Good:

• I enjoyed the rugged nature of the MSO casing and never felt like I was going to hurt the tire.  And I never did.  I ended up running around 25psi a lot of the time, 30psi tops.
• The MSO sealed up like a clam, never hinting at any sealant weeping.
• The rolling performance on smooth surfaces is very good.  Yes, it is heavy-ish, but once up to speed, you would never know that.
• I never tried to push it really hard in dirt corners and those are not aggressive knobs, so I would only expect so much.  But it puts a lot of rubber on the ground, so for the limits of a gravel bike at least, I found the cornering ability to be fine.
• It was very hard to keep the rear tire hooked up if I was climbing out of the saddle while standing and I was on a sand/gravel over hardback surface.  That center tread is pretty ridge-like.  It would quite easily let go and spin.  
• On paved roads and while cornering, the tire would give off this ‘squidgy’ sound like the knobs were squirming around.  Not sure if it really hurt anything, and the tire was never scary or anything, but it sounded odd, like cornering on an octopus.  It is not a road tire, so I will give it some slack here.  I expect any gravel ready tire with this size casing will end up feeling a bit vague and bouncy in tight, sweeping corners on pavement and at speed.  It’s just too much volume and sidewall.

After quite a few rides on this tire, I had a 30 mile ride coming up and I had another decision to make.  The ride was 2/3 pavement and featured a 10 mile, relatively smooth dirt climb, so while the MSOs would have been OK, for this ride I swapped back to my Rolf Prima wheels with the 42mm WTB Resolutes.  The difference was pretty striking.  On the road, I much preferred the 700c combo, not just for speed, but that shorter sidewall allowed for much more tire support in corners. The bigger casing of the MSO was bouncier and less inspiring on fast road sweepers and hairpins. I also noted how the bigger wheel felt like it wanted to slow down less on chattery areas and stutter bumps.  It felt snappier on anything that went uphill as well.  

But I also lost a lot of that casual approach to corners, ruts, etc, that the 650Bx50 engenders.  I ‘re-tuned’ to the 700c wheel and smaller tire, but it took a bit of time.

So what to think about 650B in this bigger tire size, that being a 50mm/2.0? If I were constantly in rough dirt I think I would run 100% of the time with the MSO Xplor.  The worse the road, the better this tire is.  However, it has precious little side knobs and a compacted tread, so traction on off camber ruts and such will reach a limit at some point.  A 650B setup also ‘quickens’ the handling of any bike designed around a 700c wheel so there is a bit of an agility gain here.  It does feel a bit ‘moto’, if that even applies to a gravel bike.  As you get onto more moderate dirt roads/smoother gravel mixed with pavement, then either wheel and tire size is OK and it comes down to preference.  And as the sliding scale moves more toward even smoother dirt and road use, I prefer the bigger rolling presence, lighter weight, and firmer cornering tire of the 700c wheel.

The 47mm size in a 650B is a bit of a tweener here.  My times on a WTB Horizon are always enjoyable and I would run them for bikepacking/light touring if I were running mostly road mixed with decent gravel or dirt.  They actually make a convincing argument for all-round, all of the time use being pretty darn fast on the road, but that bigger casing can feel bouncy and odd at times on faster pavement corners.  650Bx47mm is also a size that fits a lot of bikes so that is a win.

But this 650B in the 50mm/2.0” size is next level stuff, more like a small MTB tire, which it kind of is.  And that bump to the bigger casing brings with it a whole bunch of WHEEEE!!! and other great things when the road ahead barely looks like a road or the trail gets sketchy.  It’s good fun in a situation where less tire would be less fun.  And we do want to have fun when we ride unless we are a triathlete or one of those RAAM persons, then not so much :).  

The catch?  It’s too big for most bikes on the market and will not fit in their rear triangles.  But that might be changing as more bikes, like the new V4 Salsa Warbird, will run a 2.0”x27.5” (650B) tire and up to a 45mm 700c set-up.  I am not sure this is the way all bikes should go (and it seems to be easier to do it in carbon if you care about 2x capabilities…’tube’ shaping, etc) but any bike with pretenses of being a strong contender in gravel/exploration better be ready for this capability.  

Bottom bracket height is a bit of a caution though.  I bike with a lot of bottom bracket drop that was designed around a 700x38mm and bigger tire could be a bad deal if you convert to a 650Bx47mm combo.  I bet many folks will try this even when many manufacturers do not suggest it.  I have read of persons doing this on the new Specialized Diverge but that frame has 85mm of bottom bracket drop!  That is a LOT!  Pedals will be getting very close to the ground with a wheel downsize.  “Danger, Will Robinson!”  And I would say that any bike designed to run both wheel sizes is a bit of a compromise.  I doubt that the amount of trail designed into a geometry that is best for the smaller wheel and tire (not to mention the increased tread width) is also the best trail number and geometry for a 700cX42mm wheel and tire.  Or bottom bracket drop. Or maybe even chain stay length.  Just sayin’.  But I imagine the compromise is small enough to absorb it as we ride and tune into the bike after wheel swaps.

All that said, I really like this Donnelly MSO Xplor and it will stay in my garage as a keeper for those days where the ride calls for ‘more’.  For me, it validated this wheel/tire combo as being important and viable and I am glad that my Lynskey is capable of running both setups.  For where I live it makes sense and gives me options.

And options are good things to have.

NOTE: Donnelly sent over the MSO 650B X 50mm tires at no cost to RidingGravel.com for test and review. We were not bribed, nor paid, for this review and we will always strive to give our honest thoughts and opinions throughout.

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About The Author: Grannygear hails from SoCal and spent most of his cycling days as a mountain biker from the formative years of mountain biking all the way up to the present day. His day job is in the tech sector, but he has spent time writing about off road 4X4’s, 29″ mountain bikes, and cycling in general. Grannygear and Guitar Ted have worked off and on together since 2009 after a chance meeting at Interbike. With gravel cycling on the rise, Grannygear has been exploring how this genre’ works in SoCal and now does guest pieces for RidingGravel.com in his spare time.

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