It’s still a bike but only just

Ad­vances in elec­tric moun­tain bikes see these hi-tech wheels move closer to mopeds

The Witness - Wheels - - MOTORING - AL­WYN VILJOEN

CAR maker BMW worked with new Ger­man e-bike com­pany HNF Heisen­berg to pro­duce the XF1, the prici­est moun­tain bike yet to grace these pages.

It does for moun­tain bik­ing what a For­mula One car does for com­mut­ing.

Two mod­els of the XF1 are for sale, a 250-Watt, 25 km/h en­try level, or a 500-Watt, 45 km/h moped.

Over­seas, prices start at about R115 000 (€8 345). If the price seems steep, it is. Span­ish mo­tor­cy­cle man­u­fac­turer Bul­taco’s elec­tric moun­tain bike, the Brinco, sells for €4 800 and its 2 kW mo­tor makes 60 Nm for truly star­tling ac­cel­er­a­tion. It of­fers a lot of retro glam for a lot less jam.

The pricey XF1 does come with a first, how­ever. BMW said that the XF1 is “the world’s first mid-mo­tor, belt-driven full-sus­pen­sion e-bike”.

The swing arm al­lows the driv­e­train to move with the rear sus­pen­sion sub-frame rather than re­main se­cured to the main frame, elim­i­nat­ing re­coil from the ped­als and en­abling a more di­rect trans­fer of power.

The mo­tor moves via the piv­ot­ing rear swing arm with­out af­fect­ing the ten­sion of the belt drive. This lay­out elim­i­nates the need for a con­ven­tional chain ten­sioner and lays the path for a mid-mo­tor, car­bon belt-driven full-sus­pen­sion bike.

BMW said in a state­ment that com­pared with other rear­mounted sus­pen­sion con­cepts, which are specif­i­cally op­ti­mised for mus­cle-pow­ered drive sys­tems, there is no stiff­en­ing of the rear swing arm when the elec­tric mo­tor is pro­vid­ing a high de­gree of as­sis­tance such as dur­ing ac­cel­er­a­tion, con­stant travel at high speeds or on hills. “The sus­pen­sion can re­spond sen­si­tively at any time, en­sur­ing ex­cel­lent grip and high trac­tion,” said BMW.

The gears and knobs BMW has patented the swing arm de­sign un­der its i-clean mo­bil­ity sub-brand.

A mid-mounted Bosch mo­tor with a main­te­nance-free Gates belt drive gets power from a re­mov­able 400 W/h lithium-ion bat­tery pack that is claimed to be good for 130 km per charge. A Rohloff Speed­hub 500/14 changes gears and the XF1 rides on Rock Shox sus­pen­sions with 150 mm of travel at the rear and a 140 mm fork up­front.

To stop, the bike used Magura MT7 disc brakes. At night, a Busch & Müller Lu­motec IQ Avy head­light ban­ishes the dark­ness.

In­stead of a speedome­ter, an in­te­grated com­puter mon­i­tors the sta­tus of the elec­tric drive and pro­vides in­stant and av­er­age mea­sures of speed and dis­tance.

PHOTOS: SUPPLIED

The XF1 from Ger­man e-bike com­pany HNF Heisen­berg and BMW (left), is al­most twice the price of the Brinco, the elec­tric moun­tain bike from Span­ish mo­tor­cy­cle man­u­fac­turer Bul­taco.

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