650B and 700c much of a difference in efficiency?

Dcully

Im looking at two gravel bikes of similar spec but different wheels size.

One has 650B wheel size while the other is running 700c.

While im aware of the differences im wondering in real world terms for a casual cyclist is there much of a difference over say 80k or 100k spins in terms of speed and efficiency?

I will be mainly on canal gravel paths but also some roads so i assume the 700c would be more suited but considering

one bike is second hand but great condition [the 650B] while the other is new but with a price difference €500.

secman

Not sure about efficiency but I would be considering future servicing and replacement parts, which one is more readily available 🤔

Macy0161

I thought a lot of gravel bikes were set up to take both (a club mate runs 700c commuting, and switches out for 650b for gravel spins)?

The usual reasoning for 650b is greater tyre volume and width, which I'm not sure you'd need on canal paths?

Breezer

What’s the max. tyre clearance on the 700c bike?

saccades

650b has been pretty much dropped by MTB.

a148pro

As above I think a lot of bikes can take both but this should be apparent from the blurbs

I have a gravel bike and 700c. I've done a lot of canal riding, all of both canals and the Barrow way. You can tear along on canal tow paths so I would have thought, from what little I know about the two, that 700c makes more sense for that type of riding. I think its more efficient on long fast rides. I think 650 more designed for fatter tyres and more broken ground and steeper climbing. Don't think it would make a huge difference either way though so prob just choose which ever bike you actually prefer.

Paul Kiernan

It doesn't make any real difference. Whichever bike you get it'll take 650 or 700. 650 just means you can put bigger tyres e.g. 60mm. It'd be almost impossible to design a frame which could take 60 tyres on 700 wheels hence the need for smaller wheels. When you think about it a 700 wheel with 25 tyres has similiar rolling circumference to a 650 wheel with 50 tyres (700+25+25 v. 650+50+50).