As most manufacturers jump on the “lighter is cool” bandwagon, widening their product range with lighter and less powerful ebikes, how should you choose? Some criteria for a clearer understanding.
Do you remember the first ebikes of the early 2000’s, powered with heavy and cumbersome lead batteries? They were gross looking like a rotovator, their handling felt a bit like when I drove-tested my granny’s electric wheelchair. Their range was ridiculously narrow, their power couldn’t even compensate for their extra weight when riding uphill. A couple of times I remained stuck in the middle of nowhere, painfully pushing on the pedals to get back home on a burdensome, weird two-wheeler (I hesitate to even call it a bike). We’ve come a long way, haven’t we? Especially if we compare the ebike evolution with the slow (IMHO) progress of cars in the last 20 years.
The advantages of lighter eBikes for cyclists
We tried to exhaustively enumerate the advantages of lighter ebikes, anywhere from 12 to 20 kg (24 to 44 lbs). They can be resumed in more agility on roads and paths, easier handling to store them, especially when climbing up the stairs, and when loading them on cars and bike racks. Tires, brakes, shock absorbers, transmission gears like cassettes, chainrings and chains will wear more slowly since they have to bear less weight.
Moreover, no other transport means demands to be harmonized with its user’s body like a bicycle. Frame, crank arms, saddle, handlebar, transmission: every single part of an ebike must be carefully tailored for one’s body and riding style. This renders the ebike weight of the uttermost importance. Obviously, the lighter the ebike, the more the cyclist will feel it fitting to his body like a glove.
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- KTM Macina Race 571, 22.5 kg, 85 Nm, 3,399 €
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- KTM Macina Scarp SX Prime, 17.3 kg, 55 Nm, 7,999 €
The advantages of lighter eBikes for manufacturers
In the last few years, freight costs have a pratically tripled, while raw materials became more expensive. Lighter ebikes allow higher profit margins for each pound or kilogram manufactured and shipped. Moreover, the higher the torque, the higher manufacturing cost. Warehouse handling and delivery are also easier and cheaper with lighter items. Even their packaging is slightly less expensive.
Common configurations of standard ebikes
We consider here the most common quality city, trekking and mountain ebike sold in Europe (25kmh or 15mph assistance limit) and in the US (class 1, 20mph assistance limit, no throttle). They are mostly equipped with Bosch Performance Line CX, Yamaha PW-X / Giant SyncDrive Pro and Shimano EP8/ EP600 motors, all sporting powerful 85 Newton meters of torque, weighing from 2.6 (EP8 and PW-XM3) to 2.8 kg (Bosch Performance Line CX) , 5.72 to 6.66 lbs. Their batteries capacity is usually 625 to 630 Wh. The combination of these two values can be considered the gold standard, inasmuch their weight-to power-to price ratio is the most cherished by both cyclists and manufacturers. 500 W batteries are also quite common, oftentimes combined with slightly less powerful (65 to 80 Nm) motors. 750-800 Wh batteries are mostly found on premium e-mountain and trekking ebikes. Of course, there are also ebikes combining more powerful motors with less powerful batteries. Depending on other factors such as shock absorbers, dampers, frame and material, luggage racks, and so on, the weight of these powerful ebikes varies from 21 kg (46.2lbs) to 26 kg (57.2lbs).
Common configurations of light ebikes
The most common light ebikes feature Bosch Performance SX (55Nm, 2kg), Fazua 60 (60Nm, 1.96 kg), TQ hpr (55Nm, 1.850 kg), or Mahle X35/20 (35/20 Nm, 1.399 kg for the 20) motors. Their batteries deliver usually from 300 W to 400 W, weighing from 1.8 kg (Mahle X20) to 2.5 kg.
Price difference
As we pointed out, especially for very light ebikes, each gram of weight spared with the adoption of lighter and expensive materials, such as carbon, titanium, and so on, tends to be quite expensive. The price to quality ratio will influence purchasing decisions, according to the amount of money one is willing to invest in an ebike.
When more power primes over less weight
Reckoning that a lighter ebike can spare an average 5 kg, let’s delve into the question: when and how much is it worth bartering Newton meters for less weight?
Steep climbing underscores the importance of more Newton meters
The steeper and more frequent the climbs you must challenge, the more relevant torque becomes. Your weight plays a role too. Should you weigh for instance 80 kg, a 25 kg-85 Nm ebike would provide you 0.8 Nm per kilogram to be carried. Should you weigh 70 kg, that would be tantamount to 0.89 Nm per kg. Therefore, the less you weigh, the more your feel the power of the assistance, especially on climbs. That notwithstanding, on a 20 kg-50 Nm ebike, 80 kg and 70 kg riders would respectively enjoy only 0.50 and 0.55 Nm of torque power per kilogram. Not much, is it?
Pratically, it boils down to how often one rides without assistance and with a limited one
Indeed, when riding without assistance, beyond 25 km/h in Europe or 32 km/h ( for class 1 ebikes ) in the US, 5 kg of extra weight make a difference. One may argue that is only about 5% of the total weight (rider plus bicycle). Still, every added kilogram on an ebike is an idle weight, whereas every added kilogram on a human body involves more muscle power, or at least more weight to push down the pedals. So that 5% feels more like 10 to 20% more weight to carry.
Also, if one rides mostly with a low level of assistance, he should better choose a lighter although less powerful ebike, even if that would imply using higher levels of assistance, unless he needs more battery range.
More torque is essential if you are to carry heavy loads
Needless to say, the heavier the loads you carry, the smaller the influence of those five spared kilograms of light ebikes on your overall torque (=power) to weight ratio.
Between light – weaker, and heavier – more powerful, what would you choose?
We deem that our slight preference results from all the above. What’s yours?