Ask Miles, our Setup AI that’s been trained on the Medius X20.
Setups
Gearing
Stock gearing for the Serpent Medius X20, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 20T | 5.50 | 11.00 |
| 21T | 5.24 | 10.48 |
| 22T | 5.00 | 10.00 |
| 23T | 4.78 | 9.57 |
| 24T | 4.58 | 9.17 |
| 25T | 4.40 | 8.80 |
| 26T | 4.23 | 8.46 |
| 27T | 4.07 | 8.15 |
| 28T | 3.93 | 7.86 |
| 29T | 3.79 | 7.59 |
| 30T | 3.67 | 7.33 |
| 31T | 3.55 | 7.10 |
| 32T | 3.44 | 6.88 |
| 33T | 3.33 | 6.67 |
| 34T | 3.24 | 6.47 |
| 35T | 3.14 | 6.29 |
| 36T | 3.06 | 6.11 |
| 37T | 2.97 | 5.95 |
| 38T | 2.89 | 5.79 |
| 39T | 2.82 | 5.64 |
| 40T | 2.75 | 5.50 |
| 41T | 2.68 | 5.37 |
| 42T | 2.62 | 5.24 |
| 43T | 2.56 | 5.12 |
| 44T | 2.50 | 5.00 |
| 45T | 2.44 | 4.89 |
| 46T | 2.39 | 4.78 |
| 47T | 2.34 | 4.68 |
| 48T | 2.29 | 4.58 |
| 49T | 2.24 | 4.49 |
| 50T | 2.20 | 4.40 |
| 51T | 2.16 | 4.31 |
| 52T | 2.12 | 4.23 |
Shaded rows are the pinions most 1/10 4WD touring/gt setups run on the stock spur.
What pinion should I run?
Tell us your motor and track and get a starting pinion for the Serpent Medius X20, with the range racers in the class run.
Get a recommendation →Shop pinion gears at AMain → (opens in new tab)What pinion gear should I use on the Serpent Medius X20?
It depends on your motor and the track. In the 1/10 4WD touring/gt class, racers gear by final drive ratio: 6T and below near 7.34, 13.5T near 4.51, 17.5T near 4.51, 21.5T and up near 3.65. On the Medius X20's stock 110T spur that is about 30T for 6T and below, 49T for 13.5T, 49T for 17.5T, 60T for 21.5T and up. Tight tracks gear down, open tracks gear up. For a starting pinion matched to your motor, use the So Dialed Pinion Recommender with the Medius X20 selected.
What is the internal ratio (transmission ratio) of the Serpent Medius X20?
The Medius X20 has an internal ratio of 2:1. Final drive ratio = spur ÷ pinion × 2. With the stock 110T spur, a 20T pinion gives an FDR of 11.00 and a 52T gives 4.23.
How many teeth is the stock spur gear on the Serpent Medius X20?
110 teeth. Changing the spur moves every pinion's ratio at once; most racers leave the spur and tune with the pinion.
Kit setup
Kit shock setup. Part numbers link to AMain.
- Front
- 350 cst
- Rear
- 350 cst
- Rear
- 7,000 cst
What shock oil does the Serpent Medius X20 come with?
Out of the box the Medius X20 runs 350 cst front, 350 cst rear (Serpent oil), on 4 hole (#401841) front, 4 hole (#401841) rear pistons. That is the kit setup; you will need to adjust it for your track conditions. The RC Setup App can help dial it in.
What springs does the Serpent Medius X20 come with?
The kit springs are Yellow 2.6 (#401853) front, Yellow 2.6 (#401853) rear. Stiffer springs suit high grip and big jumps; softer springs add grip on slick or bumpy tracks.
What diff fluid does the Serpent Medius X20 come with?
The kit diff fluid is 7,000 cst rear. Thicker front adds steering on power; thicker center sends more drive rearward; thicker rear stabilizes the car under throttle.
Setup Help
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