[Closed] 650 or 700cc wheels for road/gravel

650b x 32mm woul dbe pointless, if you could actually find a tyre that size.

the second set of sizes look more realistic, 700x38 or 47x650.

700 x 40mm minimum if you want to ride it anywhere. 38mm is ok for tame stuff and cyclepaths but the extra volume over 40mm really makes a difference especially run tubeless and there is very little trade off with rolling resistance

Agree with the above, I bought a Whyte Glencoe that came with 700x38 WTB Riddlers that were a real drawback on the bike. I've since swapped to 700x42 WTB Resolutes and a tyre defender/insert on the rear - this has really transformed the bike, still having to run 40(f)/45(r) psi but can actually treat it like an XC mtb and haven't noticed it being much if any slower on the road.

I've settled on wanting 650b x 47c for my next grave;/adventure/road plus bike, either WTB horizon or byway tyres. Bigger contact patch and more volume are both better for the gravel/bridleway/rough b road riding it'll be doing.

I think 650b gives you more flexibility and ability to use wider tyres if you want to ride rougher trails. Doesn't really matter at the end of the day so may as well go for the wheelsize that gives you more tyre options.

I'm happy running 700 38 Gravel King SK's road and "gravel" (off-road stuff around south downs). I did change tyres initially, but it made next to no difference so I can't be bothered anymore, maybe just run a bit more PSI for longer rides on road.

Yea agreed on the off road stuff the 650 wins with the wider tyre.
My only concearn is if i ride any long distance road events how much more of a diadvantage is the 650 wider tyres going to be compared to a 28mm 700c tyre?

Something like the 650b WTB Byway or Horizon should roll almost as good as a thinner road tyre, but they won't have huge grip in wet stuff like the more knobbly gravel tyres.

GCN reckon they roll pretty much as good as 700c thinner tyres.

Ive gone from switching between 650b x2.0 for offroad and 700x32c for road (commuting only) and now just use 700x40c nanos. Roll over is better, comfort better and grip the same apart from proper mud. Slight drag on blacktop but I dont mind, definitely roll quicker off road.

A 700 x 45 tyre will roll even better than a 650B x 47 IME, you just can't ignore the rules of physics. I was out riding with my mate, he was running 700 x 30 Schwalbe S-Ones tubeless and I was rolling just as fast on 700 x 45 at a lower pressure. Unless you're looking at 50mm+ tyres, 650B is pointless - just a ruse by bike companies to be 'different' and try and make it appeal to MTB riders - reinvention for the sake of reinvention rather than actually making something better. The same with MTB - lots of companies jumped on 650B over 29er 'cos "it was better" and they're now back making 29ers.

I rode Tucany Trails in 17 on 650b/38 and and in 18 on 650b/47. The 47s were much more comfortable and about the same rider limited speed over 600km. We were much more confident riding on windey potholey Tuscan roads than other smaller tyred riders and a fair bit faster than them on descents.
I have just got some 700c/32 wheels which I tried out on the club run last Sunday. I had no difficulty in staying with other riders on regular road bikes even with a dynamo and a front rack.
I shall try both out on different events this year but am mostly keeping the 650b with 42mm Rock'n'Road tyres for mixed surface riding and for stuff like Gravel Dash and the 700c for more road oriented stuff.

Ok my 2c....

650b only exists on gravel bikes to fit larger tyres in typically Road bias designed frames. If you can fit 700x 40c+ in your frame, 650b is irrelevant. If you can't fit that width 700c tyre then 650b makes sense.

My only concearn is if i ride any long distance road events how much more of a diadvantage is the 650 wider tyres going to be compared to a 28mm 700c tyre?

With the right tyres fitted there's no disadvantage. I'd choose good 650s for 400km+ audax, for ex.

Dovebiker, don't forget that 700x45 isn't easy to get onto some small/mid sizes of bike inc guards, thats a factor for many. Also on tarmac the larger OD isn't so influential on rolling resistance, it's not same as 26 vs 29 offroad. There's certainly a tipping point or a crossover between 700x40ish and 650x50 though, esp for varied riding.
On balance I'm in favour of the 650s for what I do. Not scientific, just works out best for my riding, the bike layout and feel, etc.

Dovebiker, don’t forget that 700×45 isn’t easy to get onto many sizes of bike inc guards, thats a factor for many.

but surely the many have done their homework before buying and bought a bike with enough clearance for the tyres they want to run even if the stock bike comes with something smaller?

If you can fit 700x 40c+ in your frame, 650b is irrelevant. If you can’t fit that width 700c tyre then 650b makes sense.

Not necessarily. At 40mm and above in 700c the wheels can feel a bit barge like. Similar to complaints folk make about 29er mtbs. That's where 650b is good. Bigger volume tyres without the overall wheel size getting so big that it effects handling.

At 40mm and above in 700c the wheels can feel a bit barge like.

Really depends on what your riding on... It's a gravel bike, not a single-track slayer.

Really depends on what your riding on… It’s a gravel bike, not a single-track slayer

Most gravel riders in the uk will include singletrack in there rides and you don't need to be riding a slalom course for the wheels to make the bike feel like a barge. Then the bb height issue as well.

Like i said it depends on what you ride.
If your "gravel" riding mainly on single-track, then maybe...... Just maybe, You have the wrong bike and a mtb would be more suitable?
Like I said earlier to be running 700x40c, the frame needs to be designed to take it.

Gravel covers so many types of bike, terrain and riding it's very diffcult to pin one type of wheel and tyre size as a best of all world's. But just in my opinion a larger volume 700c will more comfortably out pace a similar width 650b across varied terrain.

Like i said it depends on what you ride.
If your “gravel” riding mainly on single-track, then maybe…… Just maybe, You have the wrong bike and a mtb would be more suitable?

But what be the best wheelsize for my MTB for riding in those conditions?

Depends if you want barge or slayer 😀👍

Despite the sales talk, the difference in speed will be tiny.

I'd think about availability or tyres.

You might price the weight difference.

but surely the many have done their homework before buying and bought a bike with enough clearance for the tyres they want to run even if the stock bike comes with something smaller?

Yes, for AM use or upgrades I expect so. I was thinking more of why some bikes are designed around wider 650B i/o 700x40 or 45. Balance of volume and geometry etc.

It's a grey area where it'll come down to personal stuff as well as objectives about fit, clearance, rolling resistance and higher volume/lower pressure ability.

Don't forget the effect of the gearing that this large 700x 45 tyres are going to have.