Wheel-Rim Sizing

I'm confused about how rims are referred to. Sometimes it says something
like 559x17 which I can understand, the size of the inner rim is 17mm.
Other times it says 26x1.50 or 26x1.75 which seems seems more like the
imperial sizing for tyres. I have one wheel that has 26x1.50 written on
the rim; its outer rim is about 20mm. Sometimes thinner 559x17 wheels
seem to be referred to as 26x1.75. I don't get it.

Anthony.

"damc2000" wrote in message
...

I'm confused about how rims are referred to. Sometimes it says something
like 559x17 which I can understand, the size of the inner rim is 17mm.
Other times it says 26x1.50 or 26x1.75 which seems seems more like the
imperial sizing for tyres. I have one wheel that has 26x1.50 written on
the rim; its outer rim is about 20mm. Sometimes thinner 559x17 wheels seem
to be referred to as 26x1.75. I don't get it.

Great isn't it.

559 is the rim size - that's the sensible number. 26x1.50 is the equivalent
tyre size, and that's rather more arbitrary - 26x(something decimal)
typically means 559mm ISO.

26x1.50 on the rim is more odd - sure it's not on the tyre? Ditto for the
26x1.75.

Then you've got 700c and 29" wheels - same rim, it's just the 29" have
fatter tyres.

The late Sheldon Brown wrote up a pretty definitive article he

http://sheldonbrown.com/tyre-sizing.html

Recommended.

cheers,
clive

On Sep 5, 8:08*am, "Clive George" wrote:
"damc2000" wrote in message

...



I'm confused about how rims are referred to. Sometimes it says something
like 559x17 which I can understand, the size of the inner rim is 17mm.
Other times it says 26x1.50 or 26x1.75 which seems seems more like the
imperial sizing for tyres. I have one wheel that has 26x1.50 written on
the rim; its outer rim is about 20mm. Sometimes thinner 559x17 wheels seem
to be referred to as 26x1.75. I don't get it.

Great isn't it.

559 is the rim size - that's the sensible number. 26x1.50 is the equivalent
tyre size, and that's rather more arbitrary - 26x(something decimal)
typically means 559mm ISO.

26x1.50 on the rim is more odd - sure it's not on the tyre? Ditto for the
26x1.75.


It is in Sheldon's article, but perhaps worth re-emphasising that the
rim width (eg 17 or 22) is the width of the rim in mm, and the tyre
width - whether it be in decimal or fractions - is the width of the
inflated tyre when mounted on a suitable rim. Thus these numbers are
not meant to be the same thing at all - the former is (almost) always
smaller, often substantially so. Within reason, the tyre width can be
varied independently of the rim width.

James

Clive George wrote:

559 is the rim size - that's the sensible number. 26x1.50 is the equivalent
tyre size, and that's rather more arbitrary - 26x(something decimal)
typically means 559mm ISO.

26x1.50 on the rim is more odd - sure it's not on the tyre? Ditto for the
26x1.75.

Yes it says 26x1.5 on the rim. The 26x1.75 was how it was described by
the maker, Raleigh (see http://raleigh.co.uk/p_details.aspx?id=3119),
but it has 559x17 on the rim. The problem was I was expecting it to
have be the larger 21-22mm rim. I don't know why they use the
26x-whatever sizing when they could use the ISO sizing. Maybe it's
supposed to be a guide for suitable tyres. But if you take
recommended-tyre guide in the Sheldon Brown article below of max. 2x
inner rim, a 1.75 inch (44mm) tyre would be much too wide for that rim.


The late Sheldon Brown wrote up a pretty definitive article he

http://sheldonbrown.com/tyre-sizing.html

Good article. Thanks.

Anthony.

"damc2000" wrote in message
...

Yes it says 26x1.5 on the rim. The 26x1.75 was how it was described by the
maker, Raleigh (see http://raleigh.co.uk/p_details.aspx?id=3119), but it
has 559x17 on the rim. The problem was I was expecting it to have be the
larger 21-22mm rim. I don't know why they use the 26x-whatever sizing when
they could use the ISO sizing. Maybe it's supposed to be a guide for
suitable tyres.

You're probably right - but it's also Raleigh, and they've been useless for
as long as I can remember. If I were looking for a cheapish pre-built 26"
wheel, I'd probably go elsewhere (I was going to say Chain Reaction Cycles,
but failed to drive their website appropriately - do they still do wheels?)

But if you take recommended-tyre guide in the Sheldon Brown article below
of max. 2x inner rim, a 1.75 inch (44mm) tyre would be much too wide for
that rim.

17mm is a bit narrow for that, yes. It'll probably work, but might not be
brilliant (sidewall wear?)

cheers,
clive

damc2000 writes:

But if you take recommended-tyre guide in the Sheldon Brown
article below of max. 2x inner rim, a 1.75 inch (44mm) tyre would
be much too wide for that rim.

The tyre recommendations in that table are very conservative. 559x17 is a
very common XC mountain bike rim format, and works fine with tyres up to 2"
in width.

James Thomson

On 05/09/2008 03:42, Clive George said,

(I was going to say Chain Reaction Cycles,
but failed to drive their website appropriately - do they still do wheels?)

Apparently not, which is a shame. I was looking for a wheel there the
other day.

--
Paul Boyd
http://www.paul-boyd.co.uk/

On Fri, 05 Sep 2008 13:59:11 +0100
Paul Boyd wrote:

On 05/09/2008 03:42, Clive George said,

(I was going to say Chain Reaction Cycles,
but failed to drive their website appropriately - do they still do
wheels?)

Apparently not, which is a shame. I was looking for a wheel there
the other day.

I must be missing something - there are loads of wheels shown as in
stock on their website, from £53(f) £70(r) £80(pr).