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Tech Gravel Tyre Size

Aug 23, 2009
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I can run 700x32mm in my disc brake bike. I have ridden my CX bike on single track without issue, so I feel ok with 32mm. But I noticed the gravel crowd often run bigger... 40mm+. I think I could fit a 650b with 38mm~40mm. My question is if it makes that much difference between 32mm and 38mm for Japanese off-road as I would prefer to stay with 700c? Thanks...
 

OreoCookie

Maximum Pace
Dec 2, 2017
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Yes, it should make a huge difference. The reason is that you can run much lower pressures when you keep the surface tension of the tire constant. That means you have a lot more “suspension” on your bike — a lot of people focus on the frame when talking about ride quality, but the most important factor are the tires. You can think of tires + bike as a collection of soft and hard springs. The soft tires will deform first before the harder frame “spring” compresses.

You can get great tires these days that strike a good balance between being fast on- and off-road. One example are Schwalbe's G-One Speed and their gnarlier siblings, the G-One Bite and G-One Ultrabite. (They also had a goldilocks tire, the G-One Allround, but apparently it has been discontinued.)
 
Last edited:
Aug 23, 2009
37
42
Thanks mate!

Yes, my other concern was finding tyres, whilst the Schwable links show a variety of sizes I only seem to find 35mm or 40mm. Just not sure if 40mm will fit. 38mm should be OK however all the 650b x 38mm tyres are slicks. I assume some tread is preferable when off-road here?

Will need to ponder this a little more and perhaps take some more accurate measurements of my bike.
 

TheAussieinJapan

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Apr 15, 2014
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Thanks mate!
Yes, my other concern was finding tyres, whilst the Schwable links show a variety of sizes I only seem to find 35mm or 40mm. Just not sure if 40mm will fit. 38mm should be OK however all the 650b x 38mm tyres are slicks. I assume some tread is preferable when off-road here?

Will need to ponder this a little more and perhaps take some more accurate measurements of my bike.

oh yeah it makes a huge noticeable difference. The lower pressures give lots more confidence when cornering, and road noise/vibration disappears.

I run 40mm WTB Nano Racers on my Fairdale Weekender Drop and survived the Grinduro in the typhoon. I’ve ridden the same bike on 35s but the difference with comfort is immense so I’ve stayed with 40mm which is the max my frame can handle. Your ideal gravel tyre will depend on how gnarly your ride is, surface and if it’s mud, gravel or rock. Some guys were riding massive tyres that looked 3 times wider than mine.
 
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