Project Wide Gravel Wheels v2: A Tire Swap & Impressions

 The last time I posted on the Project Wide Gravel Wheels v2 (PWGWv2) I mentioned that I wasn't all that impressed by the results I saw with a 700 X 42mm Resolute mounted up on the 30.5mm internal width Spank rims. I then made mention of possibly trying some wider tires, but not too wide, because if the tire I tried got much above 50mm in width, it wouldn't fit a gravel bike in my stable. The Black Mountain Cycles MCD actually being the only gravel bike that I own which I could even consider trying this idea. 

So, over the weekend I grabbed a set of Cannonball tires which I had tested for Riding Gravel and which are listed as 700 X 47mm in width. (Standard Disclaimer) I popped those onto the Spank rims easily with my newly resuscitated Topeak Joe Blow floor pump. The results were compared directly to the 700 X 47mm Rutland tires which I have mounted to some Spinergy GX wheels which have a 24mm internal rim width. The Cannonballs looked bigger and wider. Not by a little bit either.  

I measured the Cannonball tires on 24mm internal width rims during the Riding Gravel test and at that time they barely crossed the 49mm wide barrier. On the Spank rims? I measured these Cannonball tires out at 50.17mm in width. Whoa! Would they fit the Black Mountain Cycles MCD? I slapped on the rear tire first, because I knew that would be the deciding factor. 

It fit!

For dry use only! There isn't much clearance here!

So, now what? Well, an important factor which I detailed out in the last update on the PWGWv2, (go back to see that via the very first hyperlink in this post), was how a tire's profile can be altered by internal rim width. Too skinny or too wide is too much. How did the Cannonball look? On a 24mm internal width rim, the 700 X 47mm Cannonball was quite rounded. I felt that this was to the tire's detriment on looser surfaces. Now with the Cannonball tires on the 30.5mm internal rim width Spank rims, the profile of the tire is predictably flatter, since as the bead of each side of a tire casing gets further apart, the crown of the profile of the tire flattens out. This occurred beautifully on the Cannonball and I think it is an improvement in this instance. 

From Sunday's ride.

So, what about that Rutland in 47mm width? How do I think that would do? This tire tends to be a flatter crowned tire than the Cannonball, so my guess is that a 30.5mm internal rim width would be too much for that tire. It will flatten the crown profile even further, and that would only take away speed and to some extent, handling. 

My take away here is that the PWGWv2 is 'good' in very limited circumstances. It depends upon the tire used, and those tires have to be wider than 45mm. Also, I do not have the proper bicycle to explore the options that would, perhaps, make even more sense than the Cannonball tires do. I would need a bicycle rated for 29"er X 2.4" tires, minimum, to get everything out of these wheels that is there. At that point, these are not really "wide gravel wheels" anymore, so my conclusion from the last update holds true. 700c rims for gravel bikes probably should be in the 24mm-26mm range for internal rim widths so that they will work on gravel bikes using 700 X 38mm-45mm tires. Wider internal rim widths start to degrade a gravel tire's performance, especially on the lower end of the tire width spectrum, and on the wider end, tires may not fit frames anymore. 

Going forward, I plan on ride testing the PWGWv2 with these Cannonball tires and reporting back with a final word and plans for this wheel set's future.