27.5 wheels

[shortleg]

Hi all. Just wondering if anyone have a set 27.5 wheels set I could barrow just to try if it fits to my MTB, currently have 26. I’m thinking is upgrading the wheel to 27.5. But I just want you o try it first before I buy one. Canberra base in Belco area. Thanks

[Duck!]

Which bike are you thinking of putting them in? I can tell you now that they won't fit in the Anthem, there simply isn't enough clearance around the rear swingarm - it's even tight for moderately fat 26" tyres. At the front, although you may have enough clearance under the bridge of the fork lower, there is a very real risk of the tyre jamming against the fork crown under heavy compression, which will put you on your face in a flash. This will be a consideration for the other bikes too, but I cannot comment on their rear clearance.

[ValleyForge]

Hi all. Just wondering if anyone have a set 27.5 wheels set I could barrow just to try if it fits to my MTB, currently have 26. I’m thinking is upgrading the wheel to 27.5. But I just want you o try it first before I buy one. Canberra base in Belco area. Thanks

Begs the question - why is the 27.5 an upgrade?

[shortleg]

Thanks @duck few people said to me it’s possible and others said it’s not. I though it’s best if I do the test my self and to satisfy my decision.

@valleyforge going bigger is normally an upgrade isn’t. Better rolling over going up and down at Stromlo.

[Duck!]

Bigger wheels will help smooth out some bumps, but do little for downhill handling; that's related to the frame geometry, not the wheels hung off it.

The other thing is it will affect your effective gearing. Bigger wheels have a longer roll-out on a given gear ratio, so it effectively makes all your gears a bit higher, which may come back to bite you if you're not a strong climber.

[shortleg]

Thanks @duck. I think I rather save my energy and money and upgrade my bike. Looks like the specialized will be up for sale then.

[skull]

I did a 27.5 upgrade on my 2015 scalpel. Definitely provided an improvement, I had ridden a 29 previously too and preferred the feel of the 27.5

Downside was I had to change the 2X10 to 1X10 (that was more of an upgrade) as the wheel would hit the front mech. I also had to add an extra spacer on the lefty. I am also restricted on wheel width on the rear. I am running a 27.5 X 2.1 rocket ron and cannot go much bigger. The front wheel, being a lefty isn't as restrictive in that regard.

[singlespeedscott]

It’s 650b people, don’t fall for silly American MTB marketing.

[Duck!]

No, it's 584. Don't fall for antiquated semi-metric measurements that don't relate at all to either the rim or fitted tyre dimensions (but if you want to go on vaguely representative numbers of total diameter, it's a lot closer to 27.5" than it is to 650mm)..

[ValleyForge]

No, it's 584. Don't fall for antiquated semi-metric measurements that don't relate at all to either the rim or fitted tyre dimensions (but if you want to go on vaguely representative numbers of total diameter, it's a lot closer to 27.5" than it is to 650mm)..

Last time I asked for tubes over the counter & quoted ETRO the old bloke looked at me in a funny way. His young side-kick went straight to the shelf where he had arranged them....

[Sharkey]

No, it's 584. Don't fall for antiquated semi-metric measurements that don't relate at all to either the rim or fitted tyre dimensions (but if you want to go on vaguely representative numbers of total diameter, it's a lot closer to 27.5" than it is to 650mm)..

27.5" is pretty much 700mm but I guess 700 was already taken.
584 is 25mm bigger than a 26" wheel (559) which should make it a 27" but that was also already taken.
29", 700c and 28" are somehow all the same size at 622?
No wonder I'm confused.

[Thoglette]

27.5" is pretty much 700mm but I guess 700 was already taken.
584 is 25mm bigger than a 26" wheel (559) which should make it a 27" but that was also already taken.
29", 700c and 28" are somehow all the same size at 622?
No wonder I'm confused.

And that's only the start: here's a reasonably comprehensive list of tyre sizes (from the late, great Sheldon Brown) with no less than six different 26" rim diameters.

You need to understand the history: originally brakes were on the outside of the tyre. So the size referred to the distance from axle to brake. Then you picked how fat you wanted the tyre, which then set the rim size.

Thus you have 700, 700A, 700B and 700C all having the same outside diameter but increasingly fat tyres and smaller & smaller bead seat diameters (BSD, which is the ISO/ETRO size). Working at the same time are the forces of marketing, each in different markets, doing whatever they feel like. With the result that any sort of logic goes out the window (see 26" tyres).

Really, it's no harder than the spelling and pronunciation rules for (non-US) english. (Bow/Bow/Bow/Bough being my favourite)