Customer Review: Lauf Carbonara Fat Bike Fork

This review was written by one of our customers Steven Carmichael, where he takes an in depth look of why the Lauf Carbonara performs as well as it does. Follow along for a deeper understanding on how the Lauf fat tire fork absorbs the trail terrain. 

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Lauf's Carbonara is a fat bike composite fork having 60mm of travel with progressive spring rate. With up to 100mm deformation, fat bike tires also have progressive spring rates. To appreciate why a Carbonara is not redundant, suppose 800 Newtons per 10mm each for tire and Lauf fork. Then, for linear springs, replacing rigid with Carbonara would reduce force transmitted by 10mm bumps to 400 Newtons. However, since both are progressive, transmitted forces will be reduced by more than half. With a less progressive rate than tires, Carbonara springs deflect more for larger bumps.

Multiple leaf springs typically exhibit considerable internal friction, and ride quality can be improved by polishing and lubricating leaves, but Lauf's leaves are air-spaced and substantially undamped, as are fat bike tires. Located between two underdamped springs, wheels can judder and bounce,as can the effective mass of a bike and rider supported by this fork and tire. Bike load, wheel mass and tire pressure affect frequency of resonance. For example, a certain tire pressure sets resonance (and can provoke mild nausea) at pedal cadence rates, while front wheel resonance on washboard roads occurs for another tire pressure. This is called parametric oscillation: https://en.wikipedia.org/wiki/Parametric_oscillator

Damping reduces time a tire is bouncing out of control. Although both are underdamped springs, a Lauf has less damping than do inflated tires.
Running tubeless reduces tire rolling resistance but also reduces damping, so is less appropriate with a Lauf. After suitable tire pressure for Carbonara is obtained through trial and air (heh), rough terrain control is significantly improved over a rigid fork with any practical tire pressure.This is particularly appreciated on trampled sand or refrozen snow.

Despite what might be assumed from their videos: https://www.youtube.com/channel/UCpj9wBCYPaRVfJIfIGIBx5Q
Lauf's "USER'S MANUAL" dictates that a Carbonara is intended for neither downhill mountain biking nor dirt jumping.

My Carbonara has gloss finish and easily cleaned. Matte finishes are available. A nice FSA carbon steerer expander device was provided. Wanted but not provided are carbon assembly compound and so-called crown race, for which I suggest Cane Creek's 110-Series alloy 52/40. My 40-Series steel crown race was unusually hard to install; its corresponding location on my Carbonara crown was surprisingly poorly finished.

I like Avid's BB7 brake caliper, which is known to require a spacer and 200mm rotor for Carbonara. Other cable and most juice calipers fit with 180mm rotor and no spacer.

For the largest generally available fat tire (Vee SnowShoe 2XL 5.05"),
Lauf reportedly recommends no more than 80mm rim width; my 2XL with tube and 6psi on 100mm rim has 3mm clearance, with clear tape added for protection.

While nearly doubling my fat bike cost, Lauf's Carbonara enables carrying more speed with confidence.

Other fat bike suspension forks weigh more, require regular tedious maintenance and (based on mountain bike experience) work less well on fat bike terrain (for me: barrier island beaches). If you intend to ride a fat tire bike in all mountain bike terrain, then instead consider Bluto, RST Renegade, Wren or Cannondale Lefty