Who Knew??
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Andy B":3afxsd4t said:
Though the rim itself will have the actual diameter written on it e.g 559-xx 559 is the diameter in mm and should be quoted really.
Else you can have problems with
29" wheels and 700c wheels, both use the same size rims.
Also the 26x2.00 on a tyre is not correct, the 26 is where the 26" wheel came from but now you can get larger and thinner tyres then when the standard was made it is no incorrect as the 26 refers no to it outer diameter size any more but to a 'system'.
Hence why you need to adjust a cyclo-computer when you fit skinny tires and also your overall gear ration from pedal to tyre changes when you change tyres... oh the joys of making things simple... It does make it simple though
EDIT:
Sheldon site and Wikipedia almost certainly have something on this, if your interested
velomaniac
MacRetro Rider
A brief lesson in wheel sizes.
The international standard system uses mm and refers to the diameter of the wheel rim, outside edge to outside edge. Wheels are however often referred to by other systems which is where the confusion starts.
A 20" BMX wheel is 405mm rim edge to edge plus the tyre added.
A 24" mtb wheel is 504mm rim edge to rim edge. The 24 inches refers to the average total diameter of the wheel and inflated tyre.
A 26" mtb wheel is 559mm and as above the 26 inches refers to the overall wheel.
A road wheel is usually 622mm known as 700c which works in the same way as the above system except of course the French work in metric not inches.
A 29" mtb wheel is a 700c(28 inch) touring/hybrid rimmed wheel with a fat knobbly off road tyre fitted which works out closer to 29 inches with this fat tyre.
Now for the ever more confusing bit, there are at least 2 more wheel sizes classes as 20", one more 24", two more 26", a 27", another 28" and then several versions of several other wheel sizes. Use the international standard in mm embossed/printed on the rim to get the correct tyre size for that rim. Further some systems use the diameter value of the rim in inches as opposed to mm so that the wheel with tyre might be even bigger than stated anywhere.
See Sheldon Browns site for further details.
Confusing or what
The international standard system uses mm and refers to the diameter of the wheel rim, outside edge to outside edge. Wheels are however often referred to by other systems which is where the confusion starts.
A 20" BMX wheel is 405mm rim edge to edge plus the tyre added.
A 24" mtb wheel is 504mm rim edge to rim edge. The 24 inches refers to the average total diameter of the wheel and inflated tyre.
A 26" mtb wheel is 559mm and as above the 26 inches refers to the overall wheel.
A road wheel is usually 622mm known as 700c which works in the same way as the above system except of course the French work in metric not inches.
A 29" mtb wheel is a 700c(28 inch) touring/hybrid rimmed wheel with a fat knobbly off road tyre fitted which works out closer to 29 inches with this fat tyre.
Now for the ever more confusing bit, there are at least 2 more wheel sizes classes as 20", one more 24", two more 26", a 27", another 28" and then several versions of several other wheel sizes. Use the international standard in mm embossed/printed on the rim to get the correct tyre size for that rim. Further some systems use the diameter value of the rim in inches as opposed to mm so that the wheel with tyre might be even bigger than stated anywhere.
See Sheldon Browns site for further details.
Confusing or what
velomaniac
MacRetro Rider
How could I forget 650B although if ever a pointless wheel size was created for mtb this was it, better than 26er but not as good as 29er, whats the point ?
650A also known as 590mm also known as 26x1&3/8th" British Roadster Bikes, bicycle speedway (a knobbly tyre for this sport exists if you want to build an off roader with this size of wheel)
650B also known as 584mm, French touring bikes and continental utility machines and now mtb.
650C also known as 571mm, time trial bikes and smaller road bikes.
The madness continues.
Amusing side note, 27x1&1/4" wheels were created by raleigh and their tame tyre maker Dunlop to corner the racer/tourer market. Thus only Raleigh could supply the wheels and Dunlop the tyres
Failed miserably as everyone else copied but using better materials than the originator :roll:
650A also known as 590mm also known as 26x1&3/8th" British Roadster Bikes, bicycle speedway (a knobbly tyre for this sport exists if you want to build an off roader with this size of wheel)
650B also known as 584mm, French touring bikes and continental utility machines and now mtb.
650C also known as 571mm, time trial bikes and smaller road bikes.
The madness continues.
Amusing side note, 27x1&1/4" wheels were created by raleigh and their tame tyre maker Dunlop to corner the racer/tourer market. Thus only Raleigh could supply the wheels and Dunlop the tyres
Failed miserably as everyone else copied but using better materials than the originator :roll:
