27 inch wheels
- Thread starter hwttdz
- Start date
27" wheels are slightly larger than 700c. 27" is the old size for racing wheels. But commonly used on hybrids. Tyres are hard to get in racing sizes, but wider tyres with deeper tread are still available from some manufacturers. Not too sure what the 700c means but it is approximately 700mm diameter.
From the Vredestein E.T.R.T.O. web page:
http://www.vredestein.com/Fietsbanden/Index.asp?UserSessionID=76140559
Vredestein has been active for some considerable time in the European Tyre and Rim Technical Organisation. The E.T.R.T.O. was founded to achieve the following 3 objectives:
Harmonisation of national standards and achieving interchangeability of tyres, rims and valves in Europe with regard to fitting and use.
Achieving common design measurements, load and pressure characteristics and user guidelines.
The stimulation of free exchange of technical information concerning tyres, rims and valves.
The E.T.R.T.O. has no binding rules, but advises national organizations and international legislators about the items mentioned. In general, this advice is accepted.
Historic inch sizes
From the earliest history of the bicycle, the inch was used as the unit of measurement for bicycle tyres. In the bicycle business, for example, we talk about 24, 26, 27 and 28 inch wheels and tyres. The size is expressed in two or three numbers, e.g. 26 x 1.3/8, 26 x 2.1 of 27 x 1.1/4, the second figure refers to the width and the height of the tyre. The width is always the same as the height of the tyre!
For most sizes, three numbers are used. In the Dutch and English-speaking areas, the last figure gives the width – and therefore the height – e.g.: 28 x 1.5/8 x 1.3/8. The middle number, in combination with the first number, is a reference to the original rim size.
The German approach
In the German-speaking countries, admittedly the same sizes are used, but they are expressed in a rather different sequence: the same 28 x 1.5/8 x 1.3/8 tyre known as 28 x 1.3/8 x 1.5/8. The second figure is now the width, while the last number in combination with the first indicates the rim size. Often it is hard to tell from the tyre itself which way of expressing sizes has been used. This can be very confusing.
The French system of sizes
The French size system is expressed in millimetres instead of inches. This system uses two numbers and letter. So the 28 x 1.5/8 x 1.3/8 tyre mentioned above would be known in France as a 700 x 35C. The first number is approximately the external diameter of the wheel, while the second number indicates the width. The letter C, in combination with the first number, indicates the rim diameter.
All these size systems have the major disadvantage that it is not really clear whether a tyre will fit on a given rim or not.
Only if the size of the rim is exactly the same as the size on the tyre is it probable that the tyre will fit. If you occasionally want to fit a narrower or wider tyre, it may prove difficult to find the right tyre. E.T.R.T.O. indication Fortunately, the various size systems (which are often not used consistently) are gradually being superseded by a universal, unambiguous size code.
Manufacturers of rims and tyres have been working together to produce a standardized size system with agreed values.
The European Tyre and Rim Technical Organisation (E.T.R.T.O.) standard uses the width of the tyre and diameter of the rim in millimetres.
That means that a 28 x 1.5/8 x 1.3/8 tyre has the E.T.R.T.O. size 37-622. That means that 37 millimetres is the width and height of the tyre in inflated state, and 622 millimetres is the diameter of the rim seating, which is also decisive for the size of the tyre.
http://www.vredestein.com/Fietsbanden/Index.asp?UserSessionID=76140559
Vredestein has been active for some considerable time in the European Tyre and Rim Technical Organisation. The E.T.R.T.O. was founded to achieve the following 3 objectives:
Harmonisation of national standards and achieving interchangeability of tyres, rims and valves in Europe with regard to fitting and use.
Achieving common design measurements, load and pressure characteristics and user guidelines.
The stimulation of free exchange of technical information concerning tyres, rims and valves.
The E.T.R.T.O. has no binding rules, but advises national organizations and international legislators about the items mentioned. In general, this advice is accepted.
Historic inch sizes
From the earliest history of the bicycle, the inch was used as the unit of measurement for bicycle tyres. In the bicycle business, for example, we talk about 24, 26, 27 and 28 inch wheels and tyres. The size is expressed in two or three numbers, e.g. 26 x 1.3/8, 26 x 2.1 of 27 x 1.1/4, the second figure refers to the width and the height of the tyre. The width is always the same as the height of the tyre!
For most sizes, three numbers are used. In the Dutch and English-speaking areas, the last figure gives the width – and therefore the height – e.g.: 28 x 1.5/8 x 1.3/8. The middle number, in combination with the first number, is a reference to the original rim size.
The German approach
In the German-speaking countries, admittedly the same sizes are used, but they are expressed in a rather different sequence: the same 28 x 1.5/8 x 1.3/8 tyre known as 28 x 1.3/8 x 1.5/8. The second figure is now the width, while the last number in combination with the first indicates the rim size. Often it is hard to tell from the tyre itself which way of expressing sizes has been used. This can be very confusing.
The French system of sizes
The French size system is expressed in millimetres instead of inches. This system uses two numbers and letter. So the 28 x 1.5/8 x 1.3/8 tyre mentioned above would be known in France as a 700 x 35C. The first number is approximately the external diameter of the wheel, while the second number indicates the width. The letter C, in combination with the first number, indicates the rim diameter.
All these size systems have the major disadvantage that it is not really clear whether a tyre will fit on a given rim or not.
Only if the size of the rim is exactly the same as the size on the tyre is it probable that the tyre will fit. If you occasionally want to fit a narrower or wider tyre, it may prove difficult to find the right tyre. E.T.R.T.O. indication Fortunately, the various size systems (which are often not used consistently) are gradually being superseded by a universal, unambiguous size code.
Manufacturers of rims and tyres have been working together to produce a standardized size system with agreed values.
The European Tyre and Rim Technical Organisation (E.T.R.T.O.) standard uses the width of the tyre and diameter of the rim in millimetres.
That means that a 28 x 1.5/8 x 1.3/8 tyre has the E.T.R.T.O. size 37-622. That means that 37 millimetres is the width and height of the tyre in inflated state, and 622 millimetres is the diameter of the rim seating, which is also decisive for the size of the tyre.
Don't think that 27" business for racing is on the mark. I've seen plenty of old 700c wheels. Stuff I've seen 27" wheels on in the US was predominately lower end bike boom stuff of the 70 and early 80s. A Sheldon Brown article has the skinny on wheel sizes.
I have personally run 27" wheels on one of my older track bikes and know of many others who did the same (road bikes aswell). Now Boudreaux have u heard of something called credibility? it is a concept among "knowledgable" posters, but im not sure if you are into that sort of thing (ie. believeing somebody on the first instance with no evidence, regardless of any "credibility"). When somebody says something they shouldnt have to back it up if they know it is fact. Do u know for sure or are u just guessing about 27" not being used for racing? Maybe the US has a different sizing to us here in Australia, but 700c tyres i have used will not quite squeeze over a 27 inch rim, but a 27 inch tyre will fit very loosely over a 700c rim, and they WERE used for racing. In fact i still have some old Avocet "criterium" tyres which were slicks and i used them on the track, 27"x1".
sorry hwttdz, im not really sure when the change occurred from 27" to 700c but i remember racing as a junior on 27" and my sister had 700c. Her bike was about 2 years newer than mine. this would make the change around about the mid 80's by my estimates. Hope that helps.
To drewjc, you mention that the two sizes are very similar, do you think they are close enough to get away with running 700c wheels (smaller, correct?) on a frame originally designed for 27".
I'm thinking about building up a singlespeed/fixed gear, because it would be fun and cheap. I'm looking to pick an older frame up off of ebay, with the horizontal road dropouts that open at the front, a lot of them are 27" and if people don't say that in the listing I don't know what to assume and the contact member function seems to be faulty.
I'm thinking about building up a singlespeed/fixed gear, because it would be fun and cheap. I'm looking to pick an older frame up off of ebay, with the horizontal road dropouts that open at the front, a lot of them are 27" and if people don't say that in the listing I don't know what to assume and the contact member function seems to be faulty.
Yes some bikes from the 70's certainly had 27" wheels, so I'm guessing I may not know the wheel size until after I pick a frame.
About brakes reaching, is this the purpose of long reach brake calipers. Long reach ?
About brakes reaching, is this the purpose of long reach brake calipers. Long reach ?
Yes, long reach brakes (used to be called standard reach, then things changed) are what you would need if you want to run 700C wheels on a bike built for 27".
Now, the bike may already be able to reach; many of the older dia-compe models could certainly reach, as could some suntour (go figure).
These days, the best choice for quality/cost is probably the Shimano A550; it's a dual-pivot caliper that runs about $35 each. On an older bike, you probably want the traditional/nutted version, not the recessed version.
Watch the rear dropout width as well; older wheels had 120 or 126mm rear hubs. Steel frames can be respaced.
I've never seen 27" wheels on any modern bike! Perhaps hybrids in non-US countries use them? If so, that could be a boon to folks in the US hunting quality 27" rims. The pickings are awfully slim these days.
Yeah, that sure would! I did some checking around, and you're right, a good number of flip-flop hubs, including some affordable models, are in 120mm. Now to buy that Mercian frame I've been eyeing...
