Inner tube 100/90-18 straight valve

Size

100/90-18 inner tube: 100 mm wide, 18 inch rim. This size fits light electric motorcycles, notably the Eride Pro SR and some Sur-Ron models.

Beware of the digit order

Motorcycle notation puts the width first and the sidewall ratio second: 100/90 means 100 mm wide, with a sidewall equal to 90 % of that width. Transposing the first two figures is a common error on this type of size.

Straight valve

The valve is perpendicular to the rim, with no bend. This is the standard fitment on this type of wheel, where access to the valve is unobstructed.

Fitting

Sold individually. Inflate the tube slightly before inserting it into the tyre to avoid folds, and make sure it is not pinched between the bead and the rim before bringing it up to pressure. On a spoked wheel, also check the condition of the rim tape.