26" vs 650b

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speedsixdave
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26" vs 650b

Postby speedsixdave » 10 Aug 2019, 9:20am

Morning all,

My touring / commuting bike - The Battleship - has 26" (559) wheels with 50mm tyres. While slogging to work in a headwind recently, I wondered whether its next set of wheels (there is a long and complicated set of reasons for thinking about new wheels) should be the fashionable 650b ('27.5"' / 584), because these are clearly newer and therefore better.

My question is this: Assuming disk brake wheels with similar tyres (e.g. Marathon Supreme), and a similar overall diameter, would there be any real-world difference between 559 and 584 wheels?

26" with 50mm tyres - 559+50+50 = 659mm overall diameter
650b with 42mm tyres - 584+42+42 = 668mm o.d. (9mm bigger)
650b with 37mm tyres - 584+37+37 = 658mm o.d. (1mm smaller)
Big wheels good, small wheels better.
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reohn2
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Re: 26" vs 650b

Postby reohn2 » 10 Aug 2019, 9:31am

Peripheral wheel weight is the only real difference between the suggestions offered,with a heavier wheel and tyre accelerating slower.
The 559 example being heavier as the bigger 50mm section tyres weigh more than either of the 650b examples,with the 650b/37mm example being the lightest,all things being equal.

Edited for clarity
Last edited by reohn2 on 10 Aug 2019, 10:51am, edited 2 times in total.
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Brucey
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Re: 26" vs 650b

Postby Brucey » 10 Aug 2019, 10:37am

650B is a 26" wheel size. Should this be retitled 559mm BSD vs 584mm BSD?

As for 650B being 'newer' this is a bit of a giggle. '650B' is itself now an obsolete designation and is what the French called the already long-established 26 x 1-1/2" Dunlop size (continuously available for at least 110 years, e.g. used on every GPO bike from ~1927 to about 1980-something). Same 584mm BSD.

The 584 rim size has come back into vogue as a result of being used on MTBs (where it is known as 27.5", mostly by folk who don't know any better) and in part as a result of a renewed interest in cycle touring using 584 rims. Nonetheless trying to find anything other than 32 spoke rims in 584 ain't that easy; you are straight away down to single figures of rims with reasonable availability.

Will you notice much difference? No, not really, provided the tyres are comparably (well) built.

In the long term what will make the difference is rim and tyre availability. Right now for most utility/loaded touring purposes 559mm rim availability is still better than for the 584mm size, but that may be changing. Manufacturers are currently falling over themselves to make tyres in the 584mm size and likewise dropping tyres in the 559mm size. Obviously in extremis you can carry on running any one size until you can't buy tyres that make you happy (or at all) any more. Despite various doom-laden predictions I think this is unlikely to happen for at least 20 years in 559mm size; after all, only now you can't easily buy rims and tyres in the 26 x 1-1/4" (597mm) size despite the fact that bikes have not been made using this size for at least 30 years. Bikes with 559mm rims and tyres are still being made and sold, so they are still 'current' just less popular than they were.

cheers
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speedsixdave
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Re: 26" vs 650b (or 559 vs 584!)

Postby speedsixdave » 11 Aug 2019, 3:32pm

Thanks gents. Much as I suspected, not a lot of real-world difference.

Yes I appreciate the lack of novelty in the 650b wheel size, it was a bit of a surprise to me when it started to become fashionable again. I remember also the brief fashion for 650c wheels (571 BSD) on road bikes in about 1996. No doubt they will be back one day with great claims for increased something, perhaps when the UCI drop their 6.8kg rule.
Big wheels good, small wheels better.

Two saddles best!

hamster
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Re: 26" vs 650b

Postby hamster » 12 Aug 2019, 8:08am

Brucey wrote: Manufacturers are currently falling over themselves to make tyres in the 584mm size and likewise dropping tyres in the 559mm size. Obviously in extremis you can carry on running any one size until you can't buy tyres that make you happy (or at all) any more. Despite various doom-laden predictions I think this is unlikely to happen for at least 20 years in 559mm size;


Doubtless by then the marketing blah will have come full circle and 559 will be promoted for its light weight and magical ability to 'spin up' and offer faster acceleration. :lol: