The Heavy Hitter Adjustable Viper Direct Mount Stem is an adjustable-height, adjustable-offset direct mount stem, sold here at GritShift, for e-motos running dual crown forks with direct mount stem compatibility. It clamps 31.8 mm mountain bike bars or 1 1/8 in moto bars with the included shims, gives 2.3 in or 2.96 in of rise, and weighs 2 lb.
Specs verified September 2026 against the live GritShift product page.
Specifications
| Bar compatibility | 31.8 mm mountain bike handlebars and 1 1/8 in moto handlebars, using the included handlebar shims |
|---|---|
| Fork compatibility | E-motos running dual crown forks with direct mount stem compatibility |
| Rise without riser blocks | 2.3 in |
| Offset without riser blocks | 22.50 mm |
| Rise with riser blocks | 2.96 in |
| Offset with riser blocks | 33.50 mm or 13.50 mm, depending on which way the blocks face |
| Fine adjustment | Plus or minus 10 mm by flipping the riser blocks forward or backward |
| Mounting | Riser blocks bolt directly into the top triple clamp; the stem then bolts into the riser blocks |
| Weight | 2 lb |
| Included | Handlebar shims for 31.8 mm and 1 1/8 in bars |
What bikes does the Heavy Hitter Adjustable Viper Direct Mount Stem fit?
- Universal: e-motos with dual crown forks and direct mount stem compatibility
Why bolt the riser blocks to the triple clamp first?
Most direct mount stem risers stack riser blocks under the stem and run longer bolts straight through into the fork's top clamp. Heavy Hitter's product page identifies that as a weak point: the stack increases leverage on the hardware and loads the exact bolts that hold your bars in place. The Viper reverses the order. Its riser blocks bolt directly into the top triple clamp first, and the stem then bolts into the riser blocks, which gives a stronger, more secure mount with less leverage strain on the stem hardware.
How much rise and offset can I set?
Run the stem without the riser blocks for a 2.3 in base rise at 22.50 mm of offset. Install the offset riser blocks for a 2.96 in rise with either 33.50 mm or 13.50 mm of offset, then flip the blocks forward or backward to fine-tune the cockpit by plus or minus 10 mm. That is three distinct rise and offset combinations from one stem, plus the 10 mm trim in each direction.
Which handlebars fit the Viper?
Both common e-moto bar sizes. The stem accepts 31.8 mm mountain bike handlebars and 1 1/8 in moto bars using the handlebar shims that come in the box. Heavy Hitter designed it for e-motos running dual crown forks with direct mount stem compatibility.
Where can I buy the Heavy Hitter Adjustable Viper Direct Mount Stem (31.8 & 1-1/8th Bars)?
Right here. We sell the Heavy Hitter Adjustable Viper Direct Mount Stem (31.8 & 1-1/8th Bars) at GritShift.
