With all the components (new and also stock) of the Bestrider Pump Pro 20 kids bike in place, proper assembly can now take place!
As discussed in the earlier posts, some of the stock components are of good quality and will be reused. Examples include the wheelset, crankset and brake system.
On the other hand, other components which are not good enough will be upgraded. These include the handlebar, seat post and saddle, as well as the full drivetrain.
The stock Kenda Small Block Eight tires are more suited for light off-road riding, which is not needed here as the kids bike will be used on smooth paths only. Therefore, slick tires will be installed to reduce rolling resistance and also reduce the weight.
There are many tire choices for 20" 406 wheels, but slick ones that are wide and lightweight are not common. One of them is this Innova brand which I found, which have a claimed width of 37 mm (37-406).
Innova slick tires, 37-406 for 20" 406 wheels.
It has a folded bead which reduces the weight greatly compared to a steel wire bead. Weight is 222 grams per tire which is not that lightweight though.
One of the other tires which I considered is the Panaracer Minits Lite 32-406, which weighs just 167 grams per tire. However, the claimed width is just 32 mm, and from my experience, the actual tire width is always narrower than claimed. This makes them less suitable for the kids bike, as I prefer to install wider tires that will minimize the risk of the tire getting caught in cracks or drain grilles.
To match the new tires, I got Schwalbe SV6 inner tubes which weigh 89 grams each. No need for lightweight TPU inner tubes here.
The brown coloured side walls look good! Deore XT 11-36T 10 speed cassette has also been installed.
Weight Comparison
Stock Kenda tire: 369 grams each
Stock inner tube: 145 grams each
Stock weight per bike: 2 x (369 + 145) = 1028 grams
New Innova tire: 222 grams each
New Schwalbe SV6 inner tube: 89 grams each
New weight per bike: 2 x (222 + 89) = 622 grams
Just by swapping the tires and inner tube, over 400 grams of rotational weight can be saved! Also, changing from a knobbly tire to a slick tire will reduce rolling resistance significantly. In all, this change will greatly improve the ease of cycling by making the bike feel lighter and faster.
Another view of the stock wheelset, with new tires and cassette.
With a 1.85 mm spacer installed behind the cassette, this setup is correct, with the 11T sprocket protruding slightly above the freehub body, before tightening the lock ring.
However, actual tire width is measured to be only 32 mm wide, even though the tire is claimed to be 37 mm wide.
The rim internal width is already 20 mm, which is not considered narrow for 20 inch wheels. Therefore, the undersized tire width is not due to a narrow rim width. Rather, one trick that some tire manufacturers use is to mis-label their tire width.
In this case, even though the claimed tire width is 37 mm, the actual width is much narrower. This allows the tire manufacturer to use lesser material to make the tire, and thus claim a lower weight compared to other tires.
Not happy with this situation, so I will continue to look for wider lightweight slick tires.
Wheel diameter inclusive of tire is 470 mm.
With the wheelset settled, let's move to other parts of the bike assembly. The next focus is at the handlebar area, where the new carbon handlebar will be used.
Stock Tektro short reach brake levers, which are excellent for kids bikes. 178 grams per pair.
New lock on grips which are 95 mm instead of 130 mm long, which makes them more suited for kids bikes.
The Tektro short reach brake levers are good and will be reused, while the grips will be changed to a shorter lock-on type. At the same time, I decided to swap all the brake and shifter outer housing and also inner cables to a new set, to ensure that it is as smooth as can be. This took up quite a bit of time as I wanted to get the cable length just right.
Grips, brake levers and shifter installed on the new carbon handlebar, with ideal cable lengths.
Stock crankset with new chain ring bolts reinstalled onto the bike.
Brand new 10 speed cassette and rear derailleur installed onto the bike.
New saddle and carbon seat post installed onto the bike. I think this is the lowest position, after cutting the seat post.
The stock cable routing had the shifter cable routed on the right side of the bike, but I swapped it to the left side to run it alongside the rear brake cable.
First part of the bike assembly completed!
There is still some more work to be done to complete the bike assembly, but there is nothing much to be concerned about.
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