Suspension Fork Bolany — 34mm Stanchions on a Quick-Release Fork

The Case for 34mm Legs on a Converted Bike

Stanchion diameter is the single number that most predicts how a fork behaves once you have added a motor and a battery. Most bikes under a thousand pounds leave the factory with 28mm or 30mm legs, sized for a rider on a 13kg bicycle. Bolt on a hub motor, a downtube battery and a controller and the sprung weight goes up by roughly a third — and, more importantly, the bike now carries that speed into potholes instead of scrubbing it off.

Thin legs flex, and flex in a fork shows up as vagueness: the front wheel deflects sideways off square edges, the brake grabs and releases as the legs twist, and the bushings wear oval far quicker than they should. Going to 34mm raises stiffness sharply because a tube’s resistance to bending rises with roughly the fourth power of its diameter rather than in proportion to it — so it is a bigger step up than the four-millimetre difference sounds. That is why this is a sensible first suspension upgrade on a converted hardtail, rather than an exotic one.

Quick-Release Fitment and the Wheel That Matches

The dropouts take a 9mm quick-release skewer at 100mm spacing — still the most common front standard on non-boost mountain bikes and on almost every bike people convert. If your current front wheel is quick-release, it goes straight in. If you are building a wheel to go with it, our MTX Front Wheel Quick-Release is built to 100mm / 9mm and is the direct match; the Front Wheel MTB is the other quick-release option we stock.

One genuine warning about quick-release front ends on e-bikes: a front hub motor puts torque into the dropouts that a normal hub never does, and a QR skewer alone is not designed to resist it. If you are running a front-drive conversion, fit the torque arms supplied with your conversion kit and check the skewer tension regularly. On a rear-drive or mid-drive build this does not apply and the quick-release is perfectly happy.

Geometry, Brakes and How It Compares

Fork length is 495mm crown-to-axle in the 27.5″ version and 515mm in the 29″ version, both correct for a 100mm travel fork in those wheel sizes. Fitting the right one keeps your head angle where the frame designer intended; fitting the 29″ fork to a 27.5″ frame will slacken the steering and raise the bottom bracket noticeably. The 80mm clearance inside the arch swallows a wide trail tyre without rubbing.

Brake mounts are disc only, taking hydraulic or mechanical calipers — the Shimano BL-MT200 set is the straightforward pairing at this level. Compared with the rest of our range, the Bolany is the entry fork: single crown, quick-release, conventional geometry. Step up to the dual-crown KKE fork or NANLIO fork only if your build is genuinely heavy, fast, and running a thru-axle hub — both are far stiffer, and both need a different wheel.

Warranty and Returns

Every Bolany Suspension Fork purchased from All4eBikes is covered by a 12-month warranty against manufacturing defects, alongside a 30-day return window.