[Closed] 650b or 27.5?

Pick one and be a dick about it.

Hmm. Was 27.5" when it first (re-)appeared for MTBs. Then was B+ when everyone started doing wider (>35mm) rims, then seemed to be 27.5+ for a while. I think the 650B thing was resurrected when "Road Plus" became a thing, particularly on gravel/adventure bikes.

Edit: similar issue with 700C and 29". The former still usually applies to road bikes, the latter to MTBs but then gravel/adventure bikes are blurring boundaries.

It only bothers me when i am refining a search and they give me both options!

Hmm. Was 27.5″ when it first (re-)appeared for MTBs.

Was it?
Oh, I thought it was 6 fiddy originally and the 27.5 just came as a yankism to imperialise it...

I started out on 650b but I've now moved up to 27.5 as it just goes over the bumps that bit better, but less playful and chuckable. My next bike tho I think i'm going for 584x30 rims as I heard they are epic (totally sick)

or 584mm ERTO - 27.5" was purely marketing gumpf dreamt up for 'muricans, like 29" - they both existed in the 'old world' but needed to be reinvented.

Oh, I thought it was 6 fiddy originally and the 27.5 just came as a yankism to imperialise it…

Possibly. Not the way I remember it happening but I'm not suggesting I had my finger on the pulse that much 🙂  IIRC Tom Ritchey always favoured 650B when the Repack stuff was happening but 26" won out or we'd have had it around much more widely.

similar issue with 700C and 29″

My 700c bike became a drop bar 29er last week. The difference? An extra 4mm on the tyres. Daft.

Is the terminology ‘650b’ still really a *thing*?

Yes it's a thing

650b for gravel 27.5 for MTB

Simples

Measure the diameter of your wheel. There is your answer.

tomhoward

Pick one and be a dick about it.

I'd rather be a dick about both......pointless toss sold to idiots by shysters.

There, I feel better now. 🙂

650B's a bit European. Gammons will be much happier with an imperial 27.5, surely.

I’ve gone 27.5 front 650b rear. It’s the way I roll

650.5"+B?

I’ve gone 27.5 front 650b rear. It’s the way I roll

Yeah, I'm sold on the mullet set up too!

As Scotroutes said, MTBers like to say they are on 27.5 but gravel enthusiasts always talk about 650b wheels.

The bigger question for me is why gravel bikes are going 650b, when MTBs are going 29 (or 700c if you prefer)?

Isn't rolling speed even more of a priority for them? Is it purely a packaging issue? Will we see gravel bikes with chunkier 700c tyres in future?

The bigger question for me is why gravel bikes are going 650b, when MTBs are going 29 (or 700c if you prefer)?

Isn’t rolling speed even more of a priority for them? Is it purely a packaging issue? Will we see gravel bikes with chunkier 700c tyres in future?

ime the rollover advantage of 29 isn't really apparent on the sort of trails a generally quicker-handling drop bar bike is OK on. Tyre volume counts for more, I'd say, on road and smooth off-road tracks as well as coping with the odd root or rock better than a smaller tyre on a bigger rim. There's a cross-over point though, for sure.
You could make the gravel bike's wheels bigger to aid off-road ability, add a bit of tread, then you might think it's the bars holding you back or you've got a bad 29er and a sluggish road bike. I think it's about making bikes do something well and cover a useful range to either side 'well enough'. Trying to do it all just doesn't work out in the end. It's all subjective, terrain-influenced etc.
The other thing is wheel weight and as you say, packaging and tighter geometries esp if guard clearance is needed. 650B gives you the tyre volume in a package that's more likely to still feel quick and agile on road. But if you don't care about that then why go 650B over 700C/29er.

From what I remember the first 650B MTBs were called 650B. Pacenti Neo-Moto tyres were the first I knew of and sold as 650B, 2010 maybe. Soma had a bike called the 'B-Side' really early on. 27.5 term came in after that to position them as the inbetweener of 26" and 29" and maybe to get away from the old randonneur associations of 650B.

I've seen a move to drop the .5 and a question of 27 or 29 with Commencal , or if you're Bird just 7 or 9, of course Bird are just moving too dam quick for anything more than that.

The old system was ment to be the diameter of the wheel with the balloon of tyre.
A small balloon,
B medium Balloon
C large Balloon
I think there maybe a D balloon too

So a 650a rim is a larger diameter than a 650b rim as the balloon is smaller. Also why most 700c wheel tyre combinations are not 700mm diameter.

So being as B is a medium balloon and most MTB tyres would be a large balloon then a 650B rim with large balloon tyre will measure over 650mm we can't use 650B as a name.

But we are a metric country and should use metric measurements so 27.5 -> 698.5 mm, so let not be pedantic and call it 700..

is it just a sheep thing?

Pretty sure Mint Sauce is 26 til he dies.

Edit: similar issue with 700C and 29″. The former still usually applies to road bikes, the latter to MTBs but then gravel/adventure bikes are blurring boundaries.

And yet Continental often refer to 28" tyres for touring on 700c rims it seems...

And Schwalbe.

Wheel sizes are actually 26" 27" 28.5", so it's either a case of everything is bigger in the US or men just need to boast of that extra half inch.

We back in the early 80's we just called them 650B's as Geoff Apps hade settled on this size as the best for MTBing.

I guess the 27.5 was chosen because it is exactly half way between 26 and 29 whereas if it was referred to as 27 people may question why the need to change to a wheel that is just 1/2 inch bigger in radius and it wouldn't have been as easy to sell the "new" magical wheel size.

Thanks for that reply Jameso - that had been mildly puzzling me.

So basically, rollover's not such a significant factor because the terrain is smoother, plus a bit of packaging/weight concern.

Will we see gravel bikes with chunkier 700c tyres in future?

Monstercross has been around for a while. For me, it's partly a packaging issue that makes 650B a good compromise. Taller high volume tyres typically means larger frames and then you also start to run out of space betwixt bar/tyre and saddle/tyre in which to suspend luggage plus you increase the probability of toe overlap.

My personal experience is that 700x40 feels/is faster than 650x47 but isn't as comfy and so is more fatiguing on longer rides. Luckily a lot of frames let you switch between the two so I choose a wheelset most suited to my ride.

Can we call them 'B' wheels? It'd be a lot less of a mouthful.

700C --> C
650B --> B
26 --> A ?

I know it's not technically correct but it'd work.

I’ve gone 27.5 front 650b rear. It’s the way I roll.

I bought a new bike in 2014 with 27.5" wheels (as stated on the frame) but the front tyre said it was 650b, the rear one 27'5", both OEM. For winter I put the front on the rear and a new one on the front that said it was 27.5". Confused a LOT of people for a long time when looking at it. Even better was when the rear wheel bearings failed so I stuck an old 26" wheel in there for a few rides with a chunkier tyre. That really confused someone in the car park at Cwmcarn as the frame said 27.5", the front tyre said 650b and the rear was 26"!

Superficial
Can we call them ‘B’ wheels? It’d be a lot less of a mouthful.

700C –> C
650B –> B
26 –> A ?

I know it’s not technically correct but it’d work.

For those of us riding 650A rims, which are bigger than 650B, it's confusing enough that they are also called 26"

There's even an old British standard of 26"x2" which is a 571mm rim. That was used on bikes for export to the colonies where there were rough roads and also for the rear of trade delivery bikes. 🙂

I think we just have to accept the USA usage of 29er and 27.5" for 700C and 650B rims when they are used on mtbs.