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A planetary system may have stepped (compound) planet gears. A compound planet gear is two or more gears, side by side on the same axle, made in one piece so they turn at the same speed. Each section has a different number of teeth. One set of teeth engages the hub's ring gear and a sun gear. A different sun gear engages each additional section of the planet gears. Locking one or another sun gear to the axle achieves different ratios, possibly including ratios outside the range achievable with simple planetary gearing. Most hubs with compound planet gears have a "neutral" position when between gears, as it is not possible for two sun gears to be locked to the axle at once. This issue is difficult to avoid when the same gear train is used for both increase and decrease ratios, as the sun gears cannot freewheel in either direction: there would have to be a separate, retractible pawl for each direction of rotation..

Compound planet gears must be timed to engage all of the sun gears correctly, otherwise the teeth engaging one sun gear will be out of step with those engaging another, causing rough running and possible damage. The planet gears will have a mark somewhere to indicate how they are supposed to line up. The groove on the gear above is one example of such a mark. The image below shows the timing of the planet gears of a Sturmey-Archer Sprinter 5 hub as they are installed in the hub's planet cage.. The marks must all face directly outward.

   

Sturmey-Archer and SRAM 7-speeds (both now discontinued) are very similar to the 5-speeds, except with 3-part stepped planet gears. The ring gear engages the middle set of teeth of the planet gears. With all of these hubs, the smallest section of the planet gears must have enough teeth for acceptable strength and wear life, limiting the hub’s range.

==Mehrstufige Planetengetriebe==