E-Bikes for small riders

By Lennard Zinn

In the new world of e-bikes, cyclists under 5’5″ are stuck with an array of clunky and heavy bikes that feel like some rendition of our grandmothers grocery getter. If you have been a cyclist and are used to a quality feeling bike, it’s hard to ride something that weighs 60lbs and feels like a heavy beach cruiser. 

We have been building titanium custom electric bikes for small adults for years now and really understand what it takes to make a lightweight and performance oriented ebike that is comfortable and fun to ride.

Many of the major bike brands offer small, extra small, and even XXS, but when you actually take a minute to look at the geometry they don’t really work for an extra small person. In our research we have found several brands claiming to have a XXS gravel bike, and when we examine the geometry, the standover clearance is around 29″. They claim that this size fits a 5’0″ person, however, the average inseam length on a 5′ tall person is closer to 27″. The other issue is wheel size, crank length, and handlebar width. Stock bikes typically have stock crank lengths (165mm) , which are suitable for average leg lengths. We have been making custom bikes with shorter (proportional) crank lengths and smaller wheels for decades. Over this time we have seen that there is a demand for an off-the-shelf bike that really fits riders from 4’8″ to 5’5″.

Tui Titanium eBikes – The Best eBikes for Short Riders

When a small rider gets on a Tui titanium e-bike sized to them, they immediately express amazement at how lightweight and comfortable it is and how effortlessly and intuitively it handles, giving them a feeling of great confidence when cornering. This is no accident; it is the result of my careful and studied understanding of what the human body in general and a small body in particular requires to be properly supported on a bike for optimal pedaling efficiency, comfort, and control. Most other step-thru ebikes with full power and range weigh about 60-80 lbs making it feel heavy and cumbersome. A heavy bike is not very responsive to the rider and feels sluggish. A custom titanium e-bike or a Tui eBike for short riders  is going to be less than 40lbs and will handle more like a regular bike. You can even pedal it easily with the motor off! 

Some great features of Titanium e-Bikes

• Stiff yet poppy for excellent power transfer
• Ultra compliant for a buttery smooth feel
• Lightweight
• Extremely durable
• Dent resistant
• Can never corrode
• Read more about titanium bikes

A Tui’s strong, springy, high-modulus, 3Al/2.5V titanium tubing, precisely cut and expertly welded together, enhance its lively, efficient feel when climbing, sprinting, descending, and just rolling along. However, titanium only provides part of the magic that makes Tui the best ebikes for short riders. 

Bosch E-bike System

All of our e-bikes feature the Bosch E-bike systems. Our custom bikes feature the Generation 4 Smart System motor and batteries and the Tui e-bikes feature the Bosch Generation 4 motor with 500wh battery. Both systems have 790 max watts of power and 85nm of max torque with a max assisted speed of 28mph.

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Bike Handling

When many of the larger bike brands build electric bikes for small adults, they simply scale down a larger sized frame. This is not sufficient to make the best ebikes for short riders. A Tui titanium electric bike is fully proportional to a small person including the frame, cranks, wheels, stem, handlebar, and seat. With a Tui eBike, you will have a bike that is comfortable to ride and performs better than any other small sized electric bike. 

Crank Length

Another thing big brands do when designing electric bikes for small adults is to install disproportionately long cranks for short-legged riders. Where riders winning pro road races generally have cranks lengths around 20-21.5% of their inner-leg length, the standard 170mm cranks that come on most small bikes will be 24% of the inner-leg length of a rider with a 28-inch (71cm) inner-leg length, and 26% for a 26-inch (66cm) inner-leg length.

This means that the knees of the short-legged rider will come up disproportionately higher and their relative muscle extension and contraction and knee- and hip-angle ranges required will be greater than those of a rider with longer legs and similar crank length. This has several negative effects. One is that the short-legged rider will have to raise their handlebar substantially higher to avoid their thighs hitting their belly or chest. This negates some of the aerodynamic advantage that smaller riders naturally have by being lower in the wind than taller riders. Another is that the tighter hip angles caused by their knees coming up higher will increase tension in their hamstring and low-back muscles, potentially leading to discomfort and low-back pain. Yet another is that their sharper knee bend at the top of the stroke will mean that their quadriceps muscles will be pulling the kneecaps more directly back against the ends of their femurs when pushing down at the top of the pedal stroke, putting greater pressure on the contact between the articular cartilage on the back of the patella (kneecap) and the groove in the femur it slides up and down in during knee flexion. Chronic friction between the patella and this femoral groove can cause a painful condition called patellofemoral pain syndrome and, once the cartilage becomes damaged, chondromalacia patellae. Traditional treatments for this condition in cyclists are to increase saddle height and decrease crank length to reduce knee bend at the top of the stroke.

Cranks that are disproportionately long for small riders also mandate the steep seat-tube angles of big-brand small bikes to move the rider’s butt forward to get their knee over the forward pedal when their femur is short relative to the crank. This reduces their effective standover crotch clearance, since the steep seat angle positions the nose of the saddle further forward, requiring them to stand further forward where the bike’s up-sloping top tube is higher.

The best eBikes for short riders not only come in smaller sizes than those of big brands, but a Tui bike or e-bike will also have cranks and wheels that are in better proportion to the rider’s leg length. The XXS, XS, and S Tui gravel/road bikes fit up to 650 X 45B or 700 X 28C tires, rather than the 700 X 42C or 700 X 45C max tire size common on most gravel bikes these days, and they come standard with 155-165mm cranks, respectively. The combination of the shorter crank and smaller wheel means that the bike’s “front center” dimension—the distance from the center of the crank to the center of the front hub—doesn’t need to be nearly as long to avoid toe overlap with the front tire when turning as it would with standard 170mm cranks and 700C gravel tires. That allows me to design Tui frames with shorter top tubes than the smallest sizes from the big brands, providing better fit for smaller riders without compromising handling by requiring super-short stems. 

 

And despite having a shallow head angle (to get an even shorter top tube without pedal overlap) the Tui’s smaller wheel size doesn’t have the twitchiness at slow speed and heavy handling at high speed of big-brand small bikes. That’s because the smaller wheel radius means that, while using a fork with a standard amount of rake (offset of the front hub from the steering axis), the fork trail and wheel flop of a very tiny Tui will be like those of a mid-size bike. 

A Tui’s shorter crank in better proportion to the rider’s leg length results in a more efficient pedaling style. The knees don’t come up as high, allowing easier breathing without having to raise the handlebars so much, unnecessarily increasing aerodynamic drag. The less-sharp angles at the knee and hip at the top of the stroke with the shorter cranks reduce pressure on the backs of the kneecaps and tension in the hamstrings and low-back muscles. And the smaller wheels and large rear cassettes offer lower gear ratios better adapted to the higher pedaling cadence that shorter cranks encourage.  

The shorter crank in more standard proportion to the rider’s leg length also means that the knee can be over the forward pedal with a standard seat-tube angle rather than requiring the steep seat angles of big-brand small bikes incorporating too-long cranks. This also gives the rider more standover clearance since the saddle is not pushing them so far forward over the higher part of the top tube when standing over it. Plus, Tui bikes have lower standover height (measured from the ground to the top of the top tube at the center of its length) anyway than big-brand bikes aimed at a similar-sized rider.

Making a bike proportional to the rider’s size

It makes sense to everyone that every part of a small child’s bike is proportionately smaller than on a big bike, but this understanding seems to go out the window with adult bikes. Any parent sees the sense of the small wheels and short bicycle cranks on their kids’ first bikes and how the wheels and cranks are bigger on their next bikes as they grow. But despite the enormous difference in sizes between adult humans, wheels on adult road bikes are always 700C and cranks on adult bikes are in a narrow 165-175mm range. Not on a Tui bike, though! Everything about a Tui bike is proportional to the rider. The frame, wheels, and cranks are appropriately sized to the rider, and the saddle and handlebar widths are based on the rider’s sit-bone and shoulder widths. 

I love having the opportunity with our Tui brand to offer the best eBikes for short riders. We don’t make that claim lightly, as it is based upon years of experience designing bikes for short people.