I have some 700c which I could use for road. Should I get 650b on a new bike and use them for mixed rides?

In my opinion no. The low bb height is a distinct disadvantage.

Largely depends on the tyre clearance on your frame. Mixed is also a pretty loose term, personally I wouldn’t go any less than a 35c for the type of riding I do but did feel a huge benefit (in comfort) when I fitted a 650b/2″ tyre. But then North Yorkshire gravel is more XC MTB tbh!

As above, depends on the tyre size that you a)want and b)the frame can accommodate
47mm 650b is about the same diameter as 30mm 700c. If you use mudguards the same set will do both provided you use 50mm width
The only possible faff is getting the cassette and discs in exactly the same place on both wheelsets so that swapping wheels is simple, but that’s a one-off if any adjustment is needed

If I already had a set of 700 wheels to use then I’d get 650 wheels with the new bike and have the option.

My gravel bike has got 700s but I’d like some 650s with chunkier tyres on for the winter / rougher rides.

My wife just got new wheels for her Topstone and put 650×47 tyres on and it’s transformed the bike for her, she lives riding it off-road now. The 700s now have semi slicks for the road.

Give it a year and they’ll be selling ‘Mullet’ gravel bikes with a 700c wheel in the front and 650b in the back…

I’m surprised more frames seemingly can’t just accommodate 700x40mm tyres TBH (or can they?), which (to me) seems like a good compromise for rolling resistance vs cush…

I find myself occasionally drawn towards the idea of 650b with a ~2″ tyre for the gravel bike, but then I remember I already own an MTB and building another wheelset to make a drop barred bike try to feel more like it’s flat barred cousin is probably just going to hoover up more time and Money…

Nah 622 across the lot for me…

I’m surprised more frames seemingly can’t just accommodate 700x40mm tyres TBH (or can they?),

I think a lot / most can now, mine will take 700×50 apparently.

Yeah, all depends on frame clearance really. A gravel bike that can take proper XC 29er mtb tyres, then no. A gravel bike where the 700c clearance is limited, then yes. To answer the question about why all gravel bikes don’t just allow really big 700c tyres… it all depends on whether they are designed for road or mtb chainsets/ groupsets/ hubwidth etc. Cotic have two very different gravel bikes, each following a different approach as regards how they can be built up. I’d go and have a look at both to get an idea about what I mean. I’d put 650b fatter tyres on the Escapade, but it would be daft to do so on the Cascade. Other bikes fall between those two, so not so easy a call.

650 was a way to fit wider tyres on old bikes that didn’t have clearance. If you’re buying a new frame, chances are it has clearance for 45/50c 700c tyres. Do you need more than that? Mine can take a 2.2 MTB tyre in 650, but realistically I don’t need that as my rides are usually from the door and 50% Road, 45c has been plenty.

If they already have 700c wheels, having the second set 650b and bigger than 45/50mm makes sense. Might as well have two more different option in their case. If that works with the frame they are going to be using.

If you are around 5ft5 or under then yes. Above I’d say no, especially with the currently enlarging choice of 700c winter in the UK friendly tyres being launched. Time was a knobbly winter tyre was only available in 27.5 but those days are gone. Go 700 for the full 29 v 27.5 effect

Only if your bike won’t take large volume 700c

Yep said this loads of times, 650b on a gravel bike was just a workaround by companies who hadn’t designed a frame with proper clearance!

650b on a gravel bike was just a workaround by companies who hadn’t designed a frame with proper clearance!

Yeah, but no, but…
If you run 700c then you’re stuck with whatever tyre it comes with. Running a smaller tyre = lower BB and (fractionally) lower gearing. Dropping from a 700c 50mm to a 700c 28mm = c10mm lower BB. That may not be a problem for you

I’m talking about a new Escapade. I figure that with 700 roadish wheels and 650 intermediate, it will be like having two different bikes.

I’m worried that swapping wheels won’t be as easy as I hope….

Sounds like a plan to me. Are your existing wheels bolt thru? If so swapping should be simple. Next lot of Escapades are 853 by the way.

Yes.

I’m worried that swapping wheels won’t be as easy as I hope….

wife’s Topstone takes a couple mins, rear mech needs a full turn in or out depending which wheels and at the moment the calipers need realigning, but we’ve got some shims on the way which will hopefully solve that.

I run 700c slicks on one set of wheels and 650b 50mm off road tyres on another set.

It works well for me. Both sets us the same hubs and cassettes so wheel swapping is as easy as it could be

If I just wanted a 100% gravel bike then I think 700c with big clearance would be great. But I think that running road tyres would then be more of a compromise

Although I can’t really explain it the bike is a total hoot to ride with 650b wheels. It just seems to to steer really quickly without be unstable

Current wheels are QR so I guess I need to adapt. Hope Pro 4 I think.

650b on a gravel bike was just a workaround by companies who hadn’t designed a frame with proper clearance!

Except that 650B for all-road bikes existed long before gravel bikes. It just got a boost in re-introduction because 650 X 47 fitted into most disc CX or gravel bikes.

OP I’d get the 650s to complement your 700s. Unless you’re really after a drop bar 29er rather than an all-roader it’s pretty much an ideal tyre size imho. There’s compromises whatever you do in this area anyway.

I guess actually that I will have a set of road which I won’t use much, just for a few sportive like rides.

The other set I will use most of the time and should be good for rides which are 80% road and 20% off and also Scottish holiday gravel rides. I guess this will reduce swapping. So I guess my question is, should these wheels that I use most of the time be 650 or 700?

I really like my 650×47 tyres.

They are a bit “slower” than 700×40 but definitely add a bit of cush. That has an immediate benefit on rougher tracks but also a longer term benefit on all-day rides as I feel less beaten up too. I swap quite frequently according to terrain and duration. Short/fast rides it’s 700×40, longer rides 650×47.

What bike you on?

It’s a Van Nicholas Amazon, c. 2009.

I wasn’t expecting that but I guess you live in the right place for it.

Depends on the tyre sizes?

I found anything bigger than 700×42 just got heavy and felt slow as intrinsically there’s a point where the tyres are more capable than the short wheelbase and drop bars. But a 27.5 would get some of that zipp back.

So if the forks/stays are squared off it makes sense to have two wheelsets with the same-ish outer diameter. Makes a whole lot less sense when you see frames with 700×50 and 650×55 listed as the options.

Mine is OEM 47mm 650c, which I’ve dropped to 41mm without noticing any problems

I’d back up what tinas and Jameso have said about 650b, it’s a good option to have and it has benefits for a gravel bike. I’ve found that once 700c tyre volume gets a bit too chunky, it feels more ponderous on and off road. 650×47 does feel like a good size, as it feels fun and zippy off road and still reasonably responsive and fast rolling on road. I keep them on most of the time now, but I tend to have some off road on almost all gravel bike rides..

Hope Pro 4 I think.

Cotic have Hope parts arriving every week (often twice a week). If you order a 650b Escapade, speak to them about them getting you the Hope axle ends to convert the hubs on your 700c wheels. I’ll mention it to Paul now.

Not sure this is overly helpful, but…..

I’ve had two gravel bikes set up with 650’s and in both cases I switched to 700’s – tyre width is one consideration but I just found that the bikes felt ponderous and slow, a bit unwieldy and strangely “short” – so I went with 700’s with 38c tyres (these were a Genesis Fugio and an Orange X9 with Fox suspension) – and this transformed the ride for me –

I really like 650×47 on mine, from a comfort and grip point of view. I also like how low the whole bike is/feels for handling.

I’m sure 700×45-ish would also be great, but I’m short so with the small frame size I’d probably end up kicking my front wheel a lot when turning at slow speed. If you’re on a medium/large frame I’d go for whatever you can get/have already that you can fit a decently wide tyre to.