The advantages of which may very well be much less weight and a significantly better centre of gravity for improved dealing with
Some wonderful sleuthing by our colleagues at sister web site Bikeperfect.com has uncovered a patent utility by SRAM for a brand new and radical e-bike motor that would, and we stress might, ship huge positive factors in weight and dealing with.
As we all know, the greatest e-bikes try to juggle a number of opposing necessities: energy and vary with weight and dealing with. The extra highly effective the motor, the extra power it makes use of. The extra power it makes use of, the larger the battery it wants. However weight is the enemy of agility and dynamic dealing with, and greater batteries and motors are heavier and are harder to bundle. Which is a part of the explanation why light-weight, mid-power e-bikes are trending in the meanwhile. However as we discovered after we examined the most recent fashions – together with the Forestal Cyon, Trek Gas Ex-E, Pivot Shuttle SL and Specialised Levo SL – even essentially the most trendy, ultra-expensive e-bikes aren’t with out issues. Mainly vary, owing to the smaller batteries used to save lots of weight. Expertise has additionally taught us that full energy e-bikes with enormous batteries (such because the Canyon Spectral:ON with 900Wh battery) can ship remarkably agile dealing with with the precise geometry, suspension and packaging.
The concentric motor design seen right here is compact, liberating up house in entrance of the motor to suit the battery, held by a cage that pivots in the direction of the entrance wheel for entry
SRAM’s patent appears to use the inefficiency of present motor and battery packaging to maneuver the bike’s centre of gravity each decrease and additional again. Reducing the centre of gravity makes the bike extra steady, significantly on steep descents, and helps with cornering. Bringing the centre of gravity additional again additionally helps forestall the bike eager to tip ahead beneath braking, however moreover makes it simpler to carry the entrance wheel, which is vital in the case of making a motorbike really feel dynamic to experience.
Presently huge batteries are stuffed contained in the down tube to carry energy to the motor, however this places the heaviest a part of the system effectively in entrance of the BB and excessive within the body. In SRAM’s patent, numerous configurations are proven, however all revolve round an analogous theme; mounting the battery across the entrance of the BB on the base of the down tube. As a substitute of a cylindrical form, SRAM proposes a battery that just about wraps across the entrance of the motor. It’s held by a protecting cradle that swings ahead to permit the battery to be eliminated for charging or alternate.
This facet elevation exhibits the place of the motor and the association of the battery cells across the entrance of the motor and up into the bottom of the down tube. A 500Wh Bosch e-bike battery has 40 cells, and there are 39 seen right here, though we don’t know their capability
This leaves the down tube empty, which might permit, for instance, in-frame device storage, or, maybe an inside vary extender. Fairly than reducing a gap within the down tube, it may be constant in cross-section, which is the strongest and lightest resolution.
Right here we are able to see how the protecting cage/door swings ahead to permit the battery to be eliminated. We will additionally see the direct connection between the battery and the motor (no wires)
However how does SRAM discover room for a battery when most motors take up all of that house in entrance of the BB with a planetary drive? Good query. Effectively the reply is that SRAM’s patent exhibits a concentric motor, often called a harmonic drive, just like TQ’s newest HPR50 motor discovered within the Trek Gas EXe. This compact unit leaves house for about 40 cells in entrance of the motor. Relying on the scale of the cell, that would give as a lot as 500Wh – greater than even Fazua gives with its newest Experience 60 system.
Additional weight financial savings, packaging enhancements and reliability advantages might come from a wi-fi management system. SRAM already has the know-how, and its patent utility mentions wi-fi management between the rider and the motor/battery, presumably over energy modes. Fewer wires imply much less likelihood of water moving into the electrics and inflicting points, it additionally means much less weight, and designers don’t must work out the way to route and safe the wiring within the body. This may also make assembling bikes within the manufacturing facility a quicker, less complicated and cheaper job.
The precept downside we are able to see, offering sufficient safety could be constructed across the battery, is overheating. Conserving the motor and battery cool when they’re in such shut proximity, with decreased house for air circulation, can be a significant problem.
Whereas patent-spotting has develop into a preferred pastime for tech nerds lately, we now have to level out that making use of for authorized safety doesn’t point out {that a} product will ever attain the market. That mentioned, we all know SRAM is engaged on a motor (a prototype was noticed being ridden on the EWS Tweed Valley in June 2022), so if it does make it to market, the potential advantages might herald a large leap in e-bike efficiency.
