Cranksets, Worth the weight?

Why are the cranksets important to a child's bicycle?

 Pello Custom Crankset (chainguard and pedals removed for photo)

Pello Custom Crankset (chainguard and pedals removed for photo)

While we are patently waiting on our bikes to hit our doorstep this spring we thought we would share some of the elements that make up our crankset design since it is the component we have been working so hard to create.  

Many factors are important when thinking about a crankset, especially for your child to fit properly on the bike.  We at Pello think of the cranks as the "Center" of the bike as they perform a very important task, they transfer our energy into the bike and make us go forward.  There are about as many crank designs out there as there are fish in the sea, how is a Pello crank different?  Some of the key things to think about when choosing the right bike for your child with regards to the crankset.  Length, Width, Compatibility, Material, Gearing, Aesthetics and of course Weight.  Lets look at each of these:

 Crank length is too long ( source: bikeCAD )

Crank length is too long (source: bikeCAD)

Length - You will notice that each of our bikes have a different crank arm length depending on the model.  This is because each is designed to fit the rider for that size bike.  The length of the crank arm is an important measurement because it determines in large part how comfortable you little one will be on the bike.  Have you ever seen kids riding a bike and their knees are hitting their chest when they are seated?  Unfortunately this is a common issue on a lot of lesser expensive bikes and can mean that the cranks are too long.  More often than not cheap children's bikes source their parts from larger bikes because smaller sized parts are more expensive and not as readily available.  In fact we have had to create our own manufacturing molds for our cranksets.  Riding in this position is very unnatural, uncomfortable and isn't considered an efficient pedal stroke because the position of the leg is too compressed throughout the pedal stroke.  The ergonomics of the bike should be comfortable and feel right not awkward or unnatural. A general rule of thumb while seated is that the knee should have a slight bend at the bottom of the pedal stroke and the thigh should be slightly less than parallel to the ground at the top of the pedal stroke (please check out the image).  There are some exceptions to this rule like BMX style bikes which have long crank arms to generate more power over a short distance when racing on a BMX track (in general BMX bikes are meant to be ridden standing up, not seated).  A longer crank arm can also lead to the pedal hitting the ground while leaning the bike into a turn.  The "Lean Angle" is also an important factor in the length of the crank arms.  When going into a turn an experienced rider will move the pedal to the high side and lean into the turn to avoid the pedal hitting the ground.  However, children are still learning to ride and will often pedal continuously through a turn.  Having a shorter crank arm not only fits better but also increases the lean angle allowing children to lean further into a turn and still pedal without hitting the ground and causing a crash.  Please refer to the image for a better idea of lean angle.

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Width - The width of the cranks is often referred to as the "Q-Factor".  This dimension is basically measured from pedal to pedal and is another very important measurement because, like the length of the cranks, it allows children's legs and feet to be properly aligned with their hips as they ride creating a more comfortable and efficient pedal stroke.  Think about it this way, if I try to walk with my legs spread wide it is uncomfortable, inefficient and doesn't allow my feet to align properly with my hips and I probably won't walk very far without getting tired or sore.  Conversely if I walk normal with my legs and feet lining up with my hips I can walk for hours and still be comfortable.  This same analogy is true for pedaling, if your knees and feet are in-line with your hips then you are pedaling more efficiently and ultimately more comfortable.   Ok, so how does this work for kids?  Our cranks are custom designed with a low Q-Factor of 140mm compared to most other children's bikes that have adult Q's of 150 or in some cases more than 160mm.  Kids have little hips so they need a smaller Q than what we need.  Similar to the crank length most of the less expensive bikes have a wider Q because of availability and cost.   One way to see it in action is to watch your little one from behind as they pedal, if they look "bow-legged" then you know that the Q-Factor is too wide.

Compatibility - Since our bikes are made from high quality parts it is important that the components are compatible with other parts on the market.  For example, if your little one's grand kids :) wear out the bottom bracket (the bearings that the cranks attach to) it is simple to replace.  Any quality bike shop stock's our bottom bracket type (sealed bearing and squared taper).  This means that the parts will last a very long time and if they wear out you can simply replace the part rather than tossing the whole bike because it is broke like a cheap bike where it may cost more for a bike shop in labor to fix than the bike is worth.

Material - Our cranksets are made from high grade aluminum that provides incredible strength combined with lightweight.  Additionally the aluminum will never rust.  Many high end cranksets such as Shimano XTR still use aluminum for these very reasons.  We extended the aluminum material to the chainrings as well making them lightweight and durable.

Gearing - Another important factor in crankset design is the gearing.  Children in particular need to have a gear that is both easy to pedal but not too easy that they spin out of it immediately.  Starting with the Romper we selected a gear that is easy to get going and doesn't go too fast on the top end.  This is an important gear selection for young riders making the transition from a balance bike to their first pedal bike.  We keep this same gearing philosophy all the way through to the Revo.  When we get to the Rover models we transition into more advanced gearing.  When your little one is ready for the Rover-S (S = small) they step up to a slightly larger gear on the single speed because they are a bit stronger and we want them to keep up with mom and dad on the Sunday family rides.  The Rover-S is also available in a 2 speed version allowing your little another gear to have fun with.  The 2 speed is pretty cool as it shifts into a high or low gear automatically thanks to the SRAM Automatix rear hub.  Once their ready for more gears the Rover is waiting to roll on with 7 speeds.  Unlike the Automatix they will get to learn how to shift on their own.  Shifting is very intuitive with the SRAM Gripshift, simply twist the wrist to change gears and they can go from uber easy to climb the steepest of hills or slightly harder to hang with mom and dad on the downhills.  

Aesthetics - Since we designed our very own custom cranks we wanted to make them look as good as they perform.  If you look at the cranks carefully you will notice how some areas are shiny and some are anodized this look gives our cranks a two-tone finish that is uncommon in a children's bike.  Additionally, notice the "indentation" in the crank arm, we do this to save weight by removing material that is not needed for strength.  Our cranks are customized to fit the overall look of your Pello Bike.

 Custom Pello Crankset, low "Q-Fator" and two tone finish, standard on every Pello Bicycle.

Custom Pello Crankset, low "Q-Fator" and two tone finish, standard on every Pello Bicycle.

Lightweight - What would all these design features be if the cranks weren't lightweight?  We sweated all the details in material choice and design to make the cranks as lightweight as they could be and still be strong enough to last for years and years or for passing the bikes down through bothers and sisters everywhere.

Fun - What does all this mean?  Well if your child is more comfortable on the bike they will enjoy riding the bike longer and have more FUN!  Honestly, we really strive to create the right bike for your little one and while the cranks are simply one part of the bike we pay attention to each part as if it was our own, after all our kids ride these bikes too.