When Is Wide Too Wide?

The Noble Bikes GX5 with 700c X 47mm Teravail Cannonballs.

Last week I got these Teravail tires to check out for Riding Gravel reviews which will be trotted out over the next several weeks. (Note- I did not pay for these tires, Teravail isn't paying me to write about them. In fact, they didn't know I was going to write this post, as an example)

So, a couple pairs of these are 700c X 47mm. Yes- forty-seven millimeters. In case that doesn't impress you in some way- that's a really wide gravel tire. So wide that Teravail themselves warn you in their own marketing that they may not even fit your bike.

Regular readers also might remember that I mentioned these tires in the Last FN&V post. I said it may be that more bikes are coming that will fit these size of gravel tires. But what about now? That is a tire size that is kind of a 'no-man's land' in terms of fitment. Generally speaking, there were road and road-ish tires going up to around 700 X 42mm in the past, then you had a few outliers, like the old Continental Goliath, or that voluminous touring tire they made in the 90's, but past 42mm, there usually were no tires listed in distributor's catalogs for 700c.

There is a good reason for that. It doesn't have much to do with tires, but it has everything to do with clearances. Drive train clearances especially. There were two established standards, mostly promoted to the factories by Shimano, so they could eventually standardize the drive train business into 'road' and 'mountain' categories. Road standards allow for a certain chain line, which then pretty much dictates tire clearances in the end. Mountain allows more room, so it has a wider spindle length and crank arms that provide a wider chain line, amongst other things. This is a bit of oversimplification, but the point remains. Everything else follows the chain line and is defined by 'road' and 'mountain'. Note- there is no category for 'gravel'. Well....maybe not. (See GRX)

A close up of the 700 X 47mm Cannonball. It looks like a rasp!

So, stuffing a big tire, a chain stay, and a chain ring, plus allowing for clearance for spinning crank arms, and don't forget a drive train that is in line, (chain line), and all that together......whew! That is truly complicated stuff, and to make a change in any one of those things affects all the others. That's why when 29"ers came around companies were saying 'no way!', because making room for a big tire and a drive train plus all that other stuff- even though it could be MTB stuff- was throwing a huge wrench into the standardization pool. Remember- it took years to get parts that were 29"er friendly. This is why.

All that to say that this 700c X 47mm deal, or even Donnelly's 700c X 50mm MSO, is a weird size for a gravel tire because the limits of the road standard are being sorely tested. You might be thinking, "Well, why not use MTB standard design then!". Great idea, excepting that you have things like "Q" factor, no drive train parts which are drop bar/MTB specific, and now we have GRX.

Ah! The GRX thing! Is this Shimano's sneaky way to circumvent changing road bike standards by creating an entirely new one, outside the box of the traditionalist roadies? And when is something like a 47mm or 50mm tire appropriate for many/most riders? Isn't that just too much tire? Are we turning 'gravel' into 'drop bar mtb'? And at what point do we start seeing that the closer to 70° head angle, fully rigid hard tail bike is sorely absent from our "general purpose" off-roading options?

Add to that inner rim widths and what about these crazy wide handle bars? The cycling industry seems to be on a 'make everything wider' kick the past decade or so, and they show no signs of stopping.....yet. At some point, the pendulum of fashion and "expertise" may change and we will swing back to narrower stuff. Just wait and see.

Although, I highly doubt we go back to 17mm outer rim width roadie rims, like my Sun Mistrals, anytime soon.