Atomic BZ5

Q&A, gearing, and manual

On-road•GP•1/24-1/28 scale•4WD

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Gearing

Stock gearing for the Atomic BZ5, with common pinions and their ratios.

Stock spur

53T

Internal ratio

1.69:1

Typical pinion

17–21T

1/24-1/28 4WD gp setups. For your motor and track →

Pinion	Spur ÷ pinion	FDR
15T	3.53	5.97
16T	3.31	5.60
17T	3.12	5.27
18T	2.94	4.98
19T	2.79	4.71
20T	2.65	4.48
21T	2.52	4.27
22T	2.41	4.07
23T	2.30	3.89

Shaded rows are the pinions most 1/24-1/28 4WD gp setups run on the stock spur.

What pinion should I run?

Tell us your motor and track and get a starting pinion for the Atomic BZ5, with the range racers in the class run.

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What pinion gear should I use on the Atomic BZ5?

It depends on your motor and the track. Racers in the 1/24-1/28 4WD gp class run a 17–21 tooth pinion in most setups, usually on a 53T spur for a final drive ratio near 4.71. Hotter motors (lower turns, higher Kv) take a smaller pinion; tight tracks gear down, open tracks gear up. For a starting pinion matched to your motor, use the So Dialed Pinion Recommender with the BZ5 selected.

What is the internal ratio (transmission ratio) of the Atomic BZ5?

The BZ5 has an internal ratio of 1.69:1. Final drive ratio = spur ÷ pinion × 1.69. With the stock 53T spur, a 15T pinion gives an FDR of 5.97 and a 23T gives 3.89.