2021 Trek Rail Bosch motor bolt torque specs — what are the correct values?

[creep2fass4u]

I ride a 2021 trek rail .

Motor bolts torque specs.

@Greg Watts

 

[Greg Watts]

Right, "motor bolt torque specs" is a bit like asking "how long is a piece of string" — it depends entirely on which motor and which frame. The bolts are usually frame-specific, not motor-specific, because manufacturers love to add their own custom inserts and washers that change the spec. So here's the cheat sheet from what the forum has accumulated.

By motor / brand

Motor / Bike	Torque	Notes
Bosch CX Gen 4	20Nm	T40 Torx Plus, blue Loctite
Bosch CX Gen 5	30Nm	Different bolt design to Gen 4
Trek Rail (Bosch)	20Nm	Loctite required on reassembly
Cube (Bosch)	25–30Nm main, 13–15Nm T30 front, 9–11Nm T30 rear	Lockring 20–25Nm
DJI Avinox	20–22Nm	Per official manual
Crestline (DJI)	15Nm	Blue Loctite 242
Yamaha YDX	22Nm long / 11Nm short (drive side)
Bafang (general)	35Nm
Bafang M820 casing bolts	A few Nm only	Internal plastics crack easily
Shimano EP8/EP801	Not in dealer manual	Cover bolts 0.6Nm — contact mfr
Santa Cruz Vala	35Nm (Nate) / 30Nm (some owners)	Knocking is a known faff
Cannondale Moterra	25Nm	T40, rear bolts awkward to start
Devinci	30Nm	T40, two main bolts
Scott Lumen TQ	20Nm	Medium Loctite
Vitus E-Sommet	18Nm
Vitus E-Mythique upper shock	14Nm

Carbon frames — generally drop to 11Nm for plate bolts where the spec differs from alloy. Don't blindly apply alloy numbers to a carbon frame.

Universal rules

• Always use threadlocker — blue Loctite 242/243 unless the manual says otherwise. As @Ndanger points out, brands like Trek, Cube and Haibike use custom inserts that change the standard Bosch number, so the bike's service manual beats the motor manufacturer's manual every time.
• Use a proper calibrated torque wrench. @Philly G's Trek Rail experience is typical — bolts come loose without Loctite even at correct torque.
• Check after the first 50–100 miles, then periodically. Motor bolts work loose more than almost anything else on an eMTB.
• If a bolt ke