650 b wheels same as 26 inch?
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650 b wheels same as 26 inch?
hello folks. i have lots of confusion with wheels, tires. are 650b tires the same size as 26 inch. i see lots of folks on here that have converted 700 wheel sets on their bikes to 650 b and wondered what would be involved in doing this. i have both 26 inch rims laying about and some new 650 b tires i ordered by mistake and never got around to sending back. thanks for any help.
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hello folks. i have lots of confusion with wheels, tires. are 650b tires the same size as 26 inch. i see lots of folks on here that have converted 700 wheel sets on their bikes to 650 b and wondered what would be involved in doing this. i have both 26 inch rims laying about and some new 650 b tires i ordered by mistake and never got around to sending back. thanks for any help.
For the conversion from 700 to 650B, you need new wheels (and something to use as a brake)
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Some of your rims might have the ISO/ETRTO size printed or stamped into them. Usually, as they do on tires they put it in the tiniest print size possible. It will be written as nnn x nn or sometimes nn x nnn. Don't know for certain, but when they write it backwards I wonder if that is a sign that they don't comply fully with ISO standards. Though ISO is a voluntary standard so they certainly don't have to abide by ISO standards.
When you find the ISO size of your rim, then the three digit number will be the BSD or bead seat diameter. Knowing that, you'll know what size tire you can put on it since the ISO size will almost always be found somewhere on your tires. It too usually in the tiniest possible print embossed or stamped on the sidewall.
The two digit number in the ISO size of the rim is your internal rim width from the bead seat on one side to the other. On the tire it is the nominal width of the tire. Both in millimeters.
If any of your rims have a tire on them, then just look at the tire. Find the ISO size of the tire and you know the BSD of both.
When you find the ISO size of your rim, then the three digit number will be the BSD or bead seat diameter. Knowing that, you'll know what size tire you can put on it since the ISO size will almost always be found somewhere on your tires. It too usually in the tiniest possible print embossed or stamped on the sidewall.
The two digit number in the ISO size of the rim is your internal rim width from the bead seat on one side to the other. On the tire it is the nominal width of the tire. Both in millimeters.
If any of your rims have a tire on them, then just look at the tire. Find the ISO size of the tire and you know the BSD of both.
Last edited by Iride01; 05-18-22 at 08:08 AM.
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hello folks. i have lots of confusion with wheels, tires. are 650b tires the same size as 26 inch. i see lots of folks on here that have converted 700 wheel sets on their bikes to 650 b and wondered what would be involved in doing this. i have both 26 inch rims laying about and some new 650 b tires i ordered by mistake and never got around to sending back. thanks for any help.
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I’m no expert on vintage tire sizes, but here is how I understand it.
26” refers to the outside diameter of the tire. The actual beam/rim diameter can be anywhere from 22” to 23-1/2” (559mm to 597mm)
27” tires also refer to the outside diameter of the tire. I believe the standard beam/rim diameter was around 24-3/4” or 630mm.
In the British Empire and it’s former colony across the pond, the Imperial system of inches flourished for many years. It is so ingrained that people ride 29ers with the same bead diameter as a European road bike (622mm).
Meanwhile the French, and I suppose other countries, have a size called 650. It’s diameter was 650mm outside diameter or 25-1/2”. There is an alphabet soup of bead diameters that ranged from 22-1/2” to 23-7/16 (571mm to 590mm).
So yes 650b is historically a 26” tire, except for mountain bikers. No one will buy a 26+ mtb, so the logic is a bigger modern mountain bike tire is 27.5” in diameter. Likewise a 29” outside diameter tire can’t be called a 700mm outside diameter because it is so much beefier. But we won’t talk about 700c X 40 tires.
Such is life.
John
Edit Added: 700mm tires have been referred to as 28” tires using the rounding system from 27-1/2”. In retrospect 28” might be more accurate these days than 700mm.
26” refers to the outside diameter of the tire. The actual beam/rim diameter can be anywhere from 22” to 23-1/2” (559mm to 597mm)
27” tires also refer to the outside diameter of the tire. I believe the standard beam/rim diameter was around 24-3/4” or 630mm.
In the British Empire and it’s former colony across the pond, the Imperial system of inches flourished for many years. It is so ingrained that people ride 29ers with the same bead diameter as a European road bike (622mm).
Meanwhile the French, and I suppose other countries, have a size called 650. It’s diameter was 650mm outside diameter or 25-1/2”. There is an alphabet soup of bead diameters that ranged from 22-1/2” to 23-7/16 (571mm to 590mm).
So yes 650b is historically a 26” tire, except for mountain bikers. No one will buy a 26+ mtb, so the logic is a bigger modern mountain bike tire is 27.5” in diameter. Likewise a 29” outside diameter tire can’t be called a 700mm outside diameter because it is so much beefier. But we won’t talk about 700c X 40 tires.
Such is life.
John
Edit Added: 700mm tires have been referred to as 28” tires using the rounding system from 27-1/2”. In retrospect 28” might be more accurate these days than 700mm.
Last edited by 70sSanO; 05-19-22 at 01:08 PM.
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some very thorough and technically correct responses here, but I found the way they were presented to be a bit confusing.
WHAT YOU NEED TO KNOW
26" as was the common size on mountain bikes for many years is NOT the same as 650B. 650B rim has a bead seat diameter (the dimension that mates with the tire) of 584mm, while a 26" mountain bike wheel has a bead seat diameter of 559mm. A 650B tire will be too big to fit on a 26" rim.
The Sheldon Brown article linked above is the best resource if you want to learn about this.
WHAT YOU NEED TO KNOW
26" as was the common size on mountain bikes for many years is NOT the same as 650B. 650B rim has a bead seat diameter (the dimension that mates with the tire) of 584mm, while a 26" mountain bike wheel has a bead seat diameter of 559mm. A 650B tire will be too big to fit on a 26" rim.
The Sheldon Brown article linked above is the best resource if you want to learn about this.
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While this is a bit OT, if 26” is 559mm bead diameter and 650b is 584mm bead diameter, that is a difference of 25mm (1”) in diameter.
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
John
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
John
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While this is a bit OT, if 26” is 559mm bead diameter and 650b is 584mm bead diameter, that is a difference of 25mm (1”) in diameter.
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
Same for 27.5", which is really 650b, but again, tells you much more easily that it's bigger than a 26er but smaller than a 29er.
With the trends towards wider rims/tires in the gravel/adv segment, the line's getting blurred, but generally, "29er" has referred to 622mm wheels for all-terrain tires wider than 47mm or so (1.75" for you MTBers), and "700" for narrower, pavement-biased tires. Same for 650b -v- 27.5"
Last edited by Ironfish653; 05-19-22 at 03:18 PM.
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While this is a bit OT, if 26” is 559mm bead diameter and 650b is 584mm bead diameter, that is a difference of 25mm (1”) in diameter.
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
John
How did the industry get to 27.5?
I’m pretty sure it is just marketing to fairly uninformed consumers that wanted a size right in the middle of 26” and 29”.
John
As to where these names came from -
Bead seat diameter + 2 x nominal tire cross sectional tire diameter = nominal outside diameter of the wheel/tire
584mm/25.4mm/inch + 2 x 2.25inch = 27.5 inch
IOW a 584mm rim plus a 2.25" wide tire has an approximate nominal outside diameter of 27.5"
Similarly, a 559mm rim (trad. 26 inch mountain bike size) plus 2 x 2inch tires = 26 inch nominal outside diameter
Same goes for 700C - 622mm + 2 x 39mm tire = approx. 700mm
ANd when 700C wheels started being used for mountain bikes:
622mm/25.4mm/inch + 2 x 2.25" = 29", hence the correct although slightly confusing name of '29er'
With the fatter tires for mountain bikes, the original French 650 or 700 sizing isn't accurate, but the modern 'inch' designations kinda is when you have a particular tire size.
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Think of the size - 26" or 27.5" or 650B or 700C as the 'name' of the size - it is related to the size but not necessarily directly.
As to where these names came from -
Bead seat diameter + 2 x nominal tire cross sectional tire diameter = nominal outside diameter of the wheel/tire
584mm/25.4mm/inch + 2 x 2.25inch = 27.5 inch
IOW a 584mm rim plus a 2.25" wide tire has an approximate nominal outside diameter of 27.5"
Similarly, a 559mm rim (trad. 26 inch mountain bike size) plus 2 x 2inch tires = 26 inch nominal outside diameter
Same goes for 700C - 622mm + 2 x 39mm tire = approx. 700mm
ANd when 700C wheels started being used for mountain bikes:
622mm/25.4mm/inch + 2 x 2.25" = 29", hence the correct although slightly confusing name of '29er'
With the fatter tires for mountain bikes, the original French 650 or 700 sizing isn't accurate, but the modern 'inch' designations kinda is when you have a particular tire size.
As to where these names came from -
Bead seat diameter + 2 x nominal tire cross sectional tire diameter = nominal outside diameter of the wheel/tire
584mm/25.4mm/inch + 2 x 2.25inch = 27.5 inch
IOW a 584mm rim plus a 2.25" wide tire has an approximate nominal outside diameter of 27.5"
Similarly, a 559mm rim (trad. 26 inch mountain bike size) plus 2 x 2inch tires = 26 inch nominal outside diameter
Same goes for 700C - 622mm + 2 x 39mm tire = approx. 700mm
ANd when 700C wheels started being used for mountain bikes:
622mm/25.4mm/inch + 2 x 2.25" = 29", hence the correct although slightly confusing name of '29er'
With the fatter tires for mountain bikes, the original French 650 or 700 sizing isn't accurate, but the modern 'inch' designations kinda is when you have a particular tire size.
I won’t go to 20psi tubeless.
John
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I’m no expert on vintage tire sizes, but here is how I understand it.
26” refers to the outside diameter of the tire. The actual beam/rim diameter can be anywhere from 22” to 23-1/2” (559mm to 597mm)
27” tires also refer to the outside diameter of the tire. I believe the standard beam/rim diameter was around 24-3/4” or 630mm.
In the British Empire and it’s former colony across the pond, the Imperial system of inches flourished for many years. It is so ingrained that people ride 29ers with the same bead diameter as a European road bike (622mm).
26” refers to the outside diameter of the tire. The actual beam/rim diameter can be anywhere from 22” to 23-1/2” (559mm to 597mm)
27” tires also refer to the outside diameter of the tire. I believe the standard beam/rim diameter was around 24-3/4” or 630mm.
In the British Empire and it’s former colony across the pond, the Imperial system of inches flourished for many years. It is so ingrained that people ride 29ers with the same bead diameter as a European road bike (622mm).
Meanwhile the French, and I suppose other countries, have a size called 650. It’s diameter was 650mm outside diameter or 25-1/2”. There is an alphabet soup of bead diameters that ranged from 22-1/2” to 23-7/16 (571mm to 590mm).
So yes 650b is historically a 26” tire, except for mountain bikers. No one will buy a 26+ mtb, so the logic is a bigger modern mountain bike tire is 27.5” in diameter. Likewise a 29” outside diameter tire can’t be called a 700mm outside diameter because it is so much beefier. But we won’t talk about 700c X 40 tires.
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Thanks!
John
John
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So yes 650b is historically a 26” tire, except for mountain bikers. No one will buy a 26+ mtb, so the logic is a bigger modern mountain bike tire is 27.5” in diameter. Likewise a 29” outside diameter tire can’t be called a 700mm outside diameter because it is so much beefier. But we won’t talk about 700c X 40 tires.
Such is life.
John
Edit Added: 700mm tires have been referred to as 28” tires using the rounding system from 27-1/2”. In retrospect 28” might be more accurate these days than 700mm.
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Nope. 650c and 650b are considered the same outside diameter; 650mm. So if 650c is 26” so is 650b.
The b and c refer to the bead diameter; 584mm and 571mm.
650b tires were around before you were born.
Obviously as tires increase in width they increase in height so all sizes are not measured at 650mm outside diameter.
No different from a 700c, (c doesn’t mean clincher), X 23 through 40. They are all identified as 700mm outside diameter, but they all cannot actually measure 700mm in diameter.
John
Edit Added: If you had used etrto 584, such as 60-584, you would have been correct.
The b and c refer to the bead diameter; 584mm and 571mm.
650b tires were around before you were born.
Obviously as tires increase in width they increase in height so all sizes are not measured at 650mm outside diameter.
No different from a 700c, (c doesn’t mean clincher), X 23 through 40. They are all identified as 700mm outside diameter, but they all cannot actually measure 700mm in diameter.
John
Edit Added: If you had used etrto 584, such as 60-584, you would have been correct.
Last edited by 70sSanO; 05-19-22 at 10:37 PM.
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Nope. 650c and 650b are considered the same outside diameter; 650mm. So if 650c is 26” so is 650b.
The b and c refer to the bead diameter; 584mm and 571mm.
650b tires were around before you were born.
Obviously as tires increase in width they increase in height so all sizes are not measured at 650mm outside diameter.
No different from a 700c, (c doesn’t mean clincher), X 23 through 40. They are all identified as 700mm outside diameter, but they all cannot actually measure 700mm in diameter.
John
The b and c refer to the bead diameter; 584mm and 571mm.
650b tires were around before you were born.
Obviously as tires increase in width they increase in height so all sizes are not measured at 650mm outside diameter.
No different from a 700c, (c doesn’t mean clincher), X 23 through 40. They are all identified as 700mm outside diameter, but they all cannot actually measure 700mm in diameter.
John
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650A is also called (IIRC) 26x1-3/8 (590mm BSD) and this was a very common size up until the early/mid eighties. The 26x1-3/8 was the common name for the size - I didn't even realize it was also called 650A until a few years ago, and I owned, serviced, and sold tires for many '650A' bikes over the years.
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Like with 700D, I doubt that a 650D existed in the original French system. By that point, you'd probably be looking at wheels with a smaller nominal diameter like 600A.
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According to Sheldon Brown, the 700D did exist and was used by GT on the Tachyon. They introduced that bike in the late 80s and want to make the wheels the new standard. It didn’t work, obviously. Here’s details on the history of the Tachyon
Balloon tires on 650B rims was a well-established thing in early 20th century French bicycles, so they would have had no need to create another standard so close to it.