What does EPI mean in relation to the carcass?
The density of the carcass fabric is expressed in EPI or TPI (Ends Per Inch, Threads Per Inch). The range of carcasses used, for example, for bicycle tires are 20, 24, 37, 50, 67 and 127 EPI.
In principle, the more close-meshed a carcass is woven, the higher the quality of the tire. A dense carcass is important for low rolling resistance and good riding properties. At the same time, puncture protection increases, because carcasses with a high strand density are difficult to puncture.
However, this does not apply to the extremely fine 127 EPI carcasses, as each strand is sheer and quite vulnerable. Through extensive testing and research, Schwalbe has found that the best compromise for low weight and resistance is around 67 EPI.
In most of our top tires we use a 67 EPI carcass. Weight and rolling resistance can be reduced even further by using a 127 EPI carcass. But at the same time, these tires are more vulnerable to damage. Therefore, we intentionally use the 127 EPI carcasses only for light competition tires, where weight is an important factor.
Most bicycle tires worldwide are certainly manufactured with coarse 20 or 24 EPI materials. This material has no longer been used at all by Schwalbe for a couple of years now. Even very low-priced Schwalbe tires already have a state-of-the-art 50 EPI carcass.
But be cautious when comparing EPI indications, as often the number of strands of all carcass layers are added together. An indication of 200 TPI results e.g. from 3 layers of 67 EPI each underneath the tread.
With all EPI numbers above 150, it should be assumed that the figures have been calculated by adding up the strands in all layers. Schwalbe only indicates the material density in one carcass layer. Commonly, there are 3 carcass layers underneath the tread.
In principle, the more close-meshed a carcass is woven, the higher the quality of the tire. A dense carcass is important for low rolling resistance and good riding properties. At the same time, puncture protection increases, because carcasses with a high strand density are difficult to puncture.
However, this does not apply to the extremely fine 127 EPI carcasses, as each strand is sheer and quite vulnerable. Through extensive testing and research, Schwalbe has found that the best compromise for low weight and resistance is around 67 EPI.
In most of our top tires we use a 67 EPI carcass. Weight and rolling resistance can be reduced even further by using a 127 EPI carcass. But at the same time, these tires are more vulnerable to damage. Therefore, we intentionally use the 127 EPI carcasses only for light competition tires, where weight is an important factor.
Most bicycle tires worldwide are certainly manufactured with coarse 20 or 24 EPI materials. This material has no longer been used at all by Schwalbe for a couple of years now. Even very low-priced Schwalbe tires already have a state-of-the-art 50 EPI carcass.
But be cautious when comparing EPI indications, as often the number of strands of all carcass layers are added together. An indication of 200 TPI results e.g. from 3 layers of 67 EPI each underneath the tread.
With all EPI numbers above 150, it should be assumed that the figures have been calculated by adding up the strands in all layers. Schwalbe only indicates the material density in one carcass layer. Commonly, there are 3 carcass layers underneath the tread.
Updated on: 03/26/2025
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