Dual wheelsets for gravel bike... 2x 700 or 700 & 650

I’m going to use my gravel bike for both road and gravel rides, so I was thinking about getting 2 wheelsets to make it easy to swap based on the terrain. I think I have a handle to the differences expected between 700c/650b wheels, but then to further complicate things, I started wondering if it makes sense to have 2 700c wheelsets vs 1 each 700c/650b.

I’m 6’5" and love the idea of fat tires…I should be able to get a 700x48 and maybe a 700x50 on the bike. When I’ve ridden 700x44+ tires before, I almost feel like I’m sitting up on the bike rather than in it (if that makes any sense). This made be think that a 700x32 and 650bx2.1 would be the perfect combo since they’re about the same diameter.

On the other hand, being tall and worrying about pedal strikes on rougher terrain, it might be nice to have the extra height of a 700x48 tire but that would put me up about 17mm over 700x32/27.5x2.1.

I might be overthinking this but would love any advice folks can offer. Thank you!!!

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I have a gravel bike with two sets of 700c wheels (no dedicated road bike). I am really happy with 700/42 and 700/28 as I alternate between road and off-road (or slightly off-road and off-road). During cx season I change out the 700/42 for 700/33 (cx) and use them as a backup to my tubular wheel set (so 3 wheel sets in total, but I only use tubular for racing).

The other thing I’ll mention is that my gravel is a 1x. I have a few different chain rings and cassette options that I’ll swap around depending on how much of a specific type of riding I am planning on doing. A 42 up front and 11/36 in the back works well enough for just about everything (not optimal, but well enough to where I really only swap out components if I doing a fast road ride or an 10k climbing day).

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I have an Aspero and run 700x28 (actual width 30) for road and 650x48 (actual width 50) as my fat wheels for wherever my fancy takes me. I also have setup the stock wheels to be dedicated 700x42 (actual width 44).

I have the equivalent tires on the two gravel wheelsets (same brand/model just different size). Anytime I change from the road wheels I can pick from the 650 or 700 gravel wheels. Yet I almost never use the 700s.

Why? If I am going to ride gravel, I want the most volume in my tires, because that means more comfort, more float and more traction. The volume of 650x50 is 3.9L but it’s only 3.2L for 700x44. That might not seem like a lot, but visually and in performance it is. It’s an 22% increase.

Also, I highly recommend really supple tires. My Rene Herse knobby tires roll so well on pavement that I hardly notice them even at 20 mph. Much faster than the WTB Horizon (slick tires but thick and non-supple) that I was running before.

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I’ve been thinking the same thing for my Giant Revolt. I’d like to run 700x32s on the deep carbon rims that came stock for road and a set of 700x43s on other carbon rims, not deep, for gravel. Just got to drop the cash.

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Thanks for the tips! I’ve been looking at Rene Herse and think I’d want to try the 650b x 48 or 700x48 knobbies when I can figure out what to do about my wheels.

Your tire clearance will likely be different for 650 and 700. For some frames there’s more room for 650, on some more room for 700. It depends on the radial clearance (top of the tire), stay shaping (sides of tire). So your max 650 tire may not have more volume than your max 700 tire. For the Aspero, both of my tire sizes are maxed out (while still keeping proper mud and rock clearance).

It also will affect geometry a bit. Gravel bikes usually have lower BB than road bikes, so 650 can exaggerate that, or drop a relatively high BB to the sweet spot. Handling is affected as well. So which wheel size is better for your preferences and bike geometry may be your deciding factor.

I think it depends on how rough the gravel is that you’ll be riding. I have 700c wheels, and run 38-45 tires for the gravel around me. 45 if I know I’ll be riding on rough stuff, more jeep road than gravel road. 38 is good for proper gravel roads however.

For bike packing trips (that I have yet to go on), I’ll go bigger, and see if I can fit 50mm tires. Or if I end up doing a lot of bike packing, I’ll go with 650b wheels and 2.1 or 2.2” tires.

So I guess it comes down to the types of roads and riding that you’ll be doing. IMO, 700c 38-45 is the sweet spot for 90% of gravel riding.

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Wanted to resurrect this one as I’m going through the same thought process. Currently have a set of 700 * 40 on my Aspero on the stock wheels (heavy…), was going to order a lighter set of 700’s but I’m now toying with maybe going 650 to get the option to run higher volume tyres.

Reason I pause is most of my gravel is at least 50% tarmac and I’m wondering how the 650’s will fare on the road. Next year I’m also planning a French alps trip which will involve a lot of climbing up on tarmac before hitting the loose stuff, and again I’m wondering if a 700 might be a better choice for that though I’ll sacrifice some off road capability.

Can anyone comment on how 650’s roll on the road?

Lot’s of debate on this. My n=1 is that 650b spin up faster, feel easier on climbs (i have gotten gravel climb PRs with 650b), provide a nimble feel, and limits toe overlap with bigger tires. My sense is I lose some speed from aero, but is <1 mph in the 16-20 mph range of flat/hilly. On tarmac with Vittoria Terrano Drys. At times I do feel slower on extended road climbs with 650b. But it could also have to do with gearing differences on my gravel bike - with the low gears being much lower than my road bike.

It could be my lack of handling confidence, but I do feel the 650b wheels feel less stable at low speeds rolling over bigger rocks/roots.

Can’t comment on 650s but I’m running two set of 700s. Right now, 42 Hurricane Ridge from Rene Herse on gravel and 32 GP 5000 on the road. Love the set up. Also use a 1x and have a 10-44 cassette on the gravel wheels and 9-42 for the road (although thinking about getting a 9-36. 40t chainring on the front. Works well pretty much any situation, but maybe not optimal. But I can do fast group rides where for some sprints we are winding up to 30+ mph and I’m not spinning out.

Sounds like you have ekar @aydraper - how are you finding it?

I’m planning on doing the same as you - do you find that you can swap between cassettes without having to mess with the chain length?

2 pair of 700 in my case too. I’ve got a CX bike not a gravel (Giant TCX Advanced Pro with 2x setup) but I use it as a gravel bike and my road bike. I prefer narrow tires on gravel so I use Pirelli Cinturato Gravel H 35mm on aluminium hand built wheels and Schwalbe Pro One 28mm on FFWD carbon ones. In my case it has a lot of sense. During my travels with bike I have a lot of problems with wheels and in this setup I have always spare pair I can change tires on them if I need it.

@kevstraining love the Ekar. No problems switching between the 10-44 and 9-42. I’m thinking about trying the 9-36 and seeing if that works without a chain length. It should in that my 9-36 drops the 42 and adds a additional middle cassette. So technically I already know it works on a 36 cassette since that’s already there. I think where you run into problems is changing the chainring and the cassette, and also if you set the bike up initially for the 9-36 cassette, it might not be long enough to jump to a 42 or 44 cassette. But if you set up for the longer chain on the bigger cassette, it should work fine. You might get crisper shifting if you shorten the chain for the smaller cassette(?) but works great for me. Oh and the brakes are just amazing

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