CrankTank 3The CrankTank 3 is a lightweight and rigid high capacity hydration system that fits on nearly any triangular hardtail bike, such as MTBs, gravel bikes and road bikes, and allows you to carry up to 0. 8 gallons 3 liters of water. Compared to its big sister, the CrankTank 4, the CrankTank 3 is a bit smaller in size, has a narrower Q Factor and features an edgier design. The CrankTank kit includes everything you need to strap it on the bike and set out