Okay, so here’s what I’ve got to go by:
Trek 5200: 20 lbs. 24mm tires
Specialized Venge 16 lbs. 26mm tires (used to ride 23’s & 24’s)
Specialized Diverge 23 lbs. 28mm tires
So this is going to roam just a little bit, I’ll try to keep it tight and simple. I just rolled over 15,000 miles on the Venge – in other words, I’ve got a lot of saddle time on that bike, between 3,000 and 4,000 miles a year. In other, other words, I’m acutely aware of what the bike feels like.
My extensive experience on the Venge is only bested by that of my 5200, which I’ve been riding the longest of all my bikes.
We all know riding on rock-hard 23’s on great asphalt is fast. Those 23’s are great on good asphalt as well. These statements are not controversial, they are the truth. Unfortunately, we don’t often get great, or even good, asphalt to ride on, and that’s where the debate gets sticky.
Now, before we get into this, I can’t run anything more than a 24mm tire on the Trek. I tried a 26 last year and the paint was rubbed off of the chain stays (on my brand new stinkin’ paint job), so that bike is out of the discussion. That leaves the Venge, which will take a 26 but not much more. I’ve been riding 26mm tires for the last bit of the 2017 season and so far this season and I completely agree with reports that say the wider tires are faster on less than great pavement, and for exactly the reasons given – they smooth out road imperfections. I’m running 26mm tires at 95 psi instead of the 23’s or 24’s at 115+ and that 20 pounds over a greater surface area makes a fair bit of gnarliness go away.
See, the Venge is a true race bike. It’s stiff where it needs to be and compliant where it can be, but that’s within reason. Specialized didn’t sacrifice power-to-pedal stiffness for compliance, and with a barely padded saddle, much of the road vibration makes it through the bike to my butt. With the wider 26’s, the ride is much more enjoyable, and not noticeably slower – and keep in mind, with 15,000 miles on the bike, if it was slower, I’d know it.
So what about 28’s?
I don’t want to use 28’s, and there’s a good reason; I found out by chance that once you get to a certain level of performance, the 28’s are just too squishy unless you inflate them to a point where you’re defeating the purpose of riding the 28’s in the first place. I usually put 65-70 psi in the 28’s on my gravel bike when we’re riding them on pavement. I go with 60 on gravel roads for a little more stability. So, say I’ve got 70 psi in the tires and we’re on a stretch of pavement… I like the 28’s a lot – my gravel bike is aluminum and the 28’s smooth out the road considerably – they make the aluminum frame feel reasonable which is no small task. Normally aluminum frames are so stiff you can feel sand particles on the road – and I’m only a little hyperbolic there. They are slow, though….
So I get out of the saddle to catch the lead group. I put some serious wattage to the pedals… and the bike starts bouncing – a bounce every time I get to the power zone on the crank. And therein lies the rub. I’ve read reports that suggest going as wide as 45mm tires is better than 23’s… I’ve seen one that said 54’s. Folks, tires that wide may work fine if you’re putting about at 16 mph but if you’re going to be cruising at 23+ and sprinting for City Limit signs, let’s just say I’d be nuts going with anything more than a 26’s…. and anything more than 28, to say they’re better or faster than 23’s is simply bat-shit crazy. Comfort only goes so far against aerodynamics and rolling resistance.
Don’t agree? Try that gravel bike with 45’s in our A-Group club ride where they’re turning out a 24+ mph average. Good luck with that, Skippy. If your last name isn’t Sagan, you’re getting dropped… and that’s the whole point; the wider tires become a disadvantage shortly after 26mm.
To recap, 25’s and 26’s are excellent.
The big point I wanted to get at is that 28’s are a little too much for fast rides unless you pump them up with enough air to negate the comfort benefit of the wider tire. Anything more than 26’s I’ll save for dirt roads (and I have to tell you, on anything but freshly grated dirt roads, 28’s are excellent).