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650B is the randonneur / Original Gravel thing isn’t it. ‘UK Gravel’ can seem more drop bar 29er compatible while CX roots are 700 x 30-odd.
The interesting thing is that quite a number of bikes that used to come with 700c now come with 650. The Marin Nicasio/ally version etc for instance. Might be simply so they can market it as gravel by increasing the tyre volume without having to change the frame or it might be they think it is actually better. They aren't the only ones either.
Might be simply so they can market it as gravel by increasing the tyre volume without having to change the frame or it might be they think it is actually better.
Much truth in this, though it wasn't just marketing. I was involved with WTB's Road Plus from the start and that backward compatibility was what lead them to settle on the 47mm size. The original request was for a fatter 650B than the current tyres eg the 38-42s I had, plus tubeless. Those smaller 650s were on a Pinnacle Pyrolite road disc bike that already had the clearance for larger designed in as that similar OD point was interesting.
WTB decided on 47mm to match the OD of 700c bikes and fit into most CX frames, in the same way that B+ was designed to fit into 29er frames. WTB are a company full of riders, good people, backwards compatibility and upgrades were a priority from a rider pov as well as it helping their sales. Tests on the 1st Horizon tyres showed that the 47mm size worked well, any minor gains in going bigger were negated by difficultly in fitting to many frames out there.
B+ went from 2.8s that fitted 29er frames of the time to 3.0s and 29ers gaining clearance up to 2.6, Wide Trail etc at the same time. I've tried 650Bs up to 60mm (G-One Speeds) and though I'd like a bit bigger than 47mm at times, 42mm still feels really good on road and 60mm only feels good in a straight line, too much roll in the corners on tarmac and self-steer on uneven roads/ground for my liking. A Byway 52mm might be the ideal tyre for me but 47mm is fine, anything it won't handle is better served by a 29er of sorts.
Stop at bottom of hill, remove water bottle, throw as far up hill as you can. Get back on, climb. Stop at bottle. Repeat as necessary. Problem solved.
In my experience (on road as much as off) pedalling a 200g lighter wheelset uphill is significantly easier/faster. That weight difference is just the first example I could find where the same tyre is available in both sizes (700x50 and 650bx47) and was the Hutchinson Toureg. I am sure the difference could be even bigger with other more treaded tyres. Now, my gravel rides have very little flat in them. I am either going uphill or downhill. That means on a 6 hour ride i am spending ~4 hours going uphill. So given the choice of a lighter wheelset or one that rolls slightly better (lets not forget the 650b are high volume, low pressure) on rough ground i know what i will choose.
@jameso you might like the 650x47 Rutlands. Better grip than the Byway but rolls like a Nano 40. Always down to mix of terrain of course but I can usually choose routes avoiding too much tarmac.
In my experience (on road as much as off) pedalling a 200g lighter wheelset uphill is significantly easier/faster.
Could you quantify that with times on climbs?
What do you weigh?
This is how see it
Bike plus rider=60+10=70kg (for me the number is over 100kg)
% difference 200g makes 0.2*100/70=0.3%
Time saved on climb is 1 hour climb=0.3*60*60/100=11 seconds
Now that could win the tour de France but I really don't think I'd notice. Although i accept feel isn't the same thing as time
In my experience (on road as much as off) pedalling a 200g lighter wheelset uphill is significantly easier/faster.
Whereas in my experience in makes no noticeable difference. Quite a different experience from your "significantly easier/faster". I can feel the difference but the actual difference (timed over many miles) is just simply not there.
Could you quantify that with times on climbs?
Unscientifically, yes. Local climb of 1 mile took me 1 minute less to climb with a new wheelset that was 100g per wheel lighter.
Im not bothered if you think its true or not, just trying to make a point that reducing weight of moving parts has a bigger effect than reducing the weight of static ones.
The weight thing does only apply if you're comparing similarly sized tyres though, which is a daft comparison. Going from 29x1.8 to 27.5x1.8 just drops the BB by ~19mm (or vice versa raises it by 19mm).
If a frame is designed for 650b x47mm then the faster/smoother option is 700c x 32mm (approximately the same diameter).
The weights for those sizes work out something like:
WTB ByWay 650*47 564g
700x34 396g
DT G540 650b - 530g
Dt R500 700c - 495g
So overall the 650b option is actually 200g heavier. If you do it in a way that doesn't mess with the geometry.
Personally, I didn't get on with a 700x55mm gravel bike on XC tyres, it was just heavy and incapable. 700x42mm (and light flexy tyres at that) is a much better compromise of grip/cushioning/talent/capability. The exception to that might be riding something like the GDR of GBDuro where you'd probably pick skinny tyres, but need the cushioning for some bits when fully loaded. And would probably prefer a 29er for those bits too but drop bars are the better compromise for comfort and speed. But those are quite a niche set of circumstances.
The other advantage would be aerodynamical, you're lobbing ~40mm off the height of the wheel (for the same tyre size), that's a chunk of watts.
The weight thing does only apply if you’re comparing similarly sized tyres though, which is a daft comparison. Going from 29×1.8 to 27.5×1.8 just drops the BB by ~19mm (or vice versa raises it by 19mm).
If a frame is designed for 650b x47mm then the faster/smoother option is 700c x 32mm (approximately the same diameter).
The weights for those sizes work out something like:
WTB ByWay 650*47 564g
700×34 396gDT G540 650b – 530g
Dt R500 700c – 495gSo overall the 650b option is actually 200g heavier. If you do it in a way that doesn’t mess with the geometry.
Agreed, but the comparisons being made on the first page were big volume 700c like 50mm and 650bx47.
Unscientifically, yes. Local climb of 1 mile took me 1 minute less to climb with a new wheelset that was 100g per wheel lighter.
Im not bothered if you think its true or not, just trying to make a point that reducing weight of moving parts has a bigger effect than reducing the weight of static ones.
That can't be down to weight can it? I've seen a few comparisons that confirmed the sort of calculations I've done but in the real world. They of course used a power meter to make sure that wasn't a variable
Agreed, but the comparisons being made on the first page were big volume 700c like 50mm and 650bx47.
Sorry if I've missed a nuance in the debate, I saw you were. But everyone else seemed to be talking wider 650b vs narrow 700c. This is why I pointed out the weight change is generally in the other direction unless you do as you say and try and keep the same tyre width, which has the knock-on downside of changing geometry too.
I was looking at some frames recently and the manufacturer was making a big deal of it fitting 700x52 tyres and 650x55mm, but looking at the geometry it was pretty close to the "relaxed CX bike" end of things. kinda felt like they were hobbling their own bike a bit by trying to convince users it was even more versatile than it was with a 3rd wheelsize option (650b, 700c and "29er") that really just added weight and raised the BB.
Local climb of 1 mile took me 1 minute less to climb with a new wheelset that was 100g per wheel lighter.
Im not bothered if you think its true or not
You may not be bothered but that is just simply impossible, physics eh.
Is the CdF dull and lifeless as some have said in comparison?
I had 3 of them and never found them to feel that way.
In my experience (on road as much as off) pedalling a 200g lighter wheelset uphill is significantly easier/faster.
Yeah, forgive my joke, I know what you mean. The mass at the extreme of the rotational disc does make a difference. I have certainly felt that the bigger tyres on bigger wheels are harder to spin up to speed. I've never tried to quantify a difference in terms of power or time but I don't have trouble believing it exists. If sprint wheels with sliding weights didn't work, the pros wouldn't have used them.
I had 3 of them and never found them to feel that way.
Interesting, thanks. It seems like it's a marmite thing. Some owners really felt they were dead, others not at all. At the moment the yellow frame, and tyre clearance is holding me back