Michelin Tube-21" Front

Michelin "Airstop" Butyl Inner Tube - for 19 inch front wheels.

This tube fits the following tire sizes:
2.50-21 | 2.75-21 | 3.00-21
80/90-21 | 90/90-21 | 80/100-21 | 90/100-21
MH90-21

What’s the difference between “Butyl” and “Natural” rubber?
Butyl, used by Michelin and others, is a synthetic material with two advantages. One is that it is much less porous than real rubber which means you will not have to check tire pressure nearly as often to be confident of proper inflation. The second advantage is that it is much less expensive.
Natural rubber, used by Metzeler, is more expensive material, and it is a naturally porous which means it requires more frequent attention to assure proper inflation. It does have one notable advantage, however. Natural rubber is a more resilient and forgiving material, thus it is less likely to puncture or tear, and when it does, deflation tends to happen more “gracefully.” In addition, natural rubber can be patched effectively in most cases. Butyl blowouts, on the other hand, can be rather sudden or severe, and patching is rarely possible.

Don't forget a fresh rim band strip. See recommended products.