Bestrider Pump Pro 16: Saddle and Seatpost Upgrade

The Bestrider Pump Pro 16 kids bike came with a decent small saddle for kids, but the lack of adjustability is a problem. Only the saddle height can be adjusted via the seatpost height, while the saddle fore/aft and tilt cannot be adjusted at all. This is because the saddle attaches to the seat post via a pipe-fitting interface (refer to pictures below), instead of using the common saddle rail interface.

Another issue was that this pipe-fitting interface had looseness between the saddle and the seat post which could not be eliminated. To be honest, this kind of interface is not good at all, and only used because it is cheap.

Therefore, to optimize the saddle position for proper riding, I decided to get a new kids-specific saddle for this bike. As the stock seat post does not have a clamp for saddle rails, I also had to get a new seat post at the same time.

I found that it was nearly impossible to get a decent kids saddle that is not too big or with overly-thick cushion. There are very few options available.

Finally I found a source which had this SDG Fly Junior saddle that is highly rated for kids. There was practically no second option for a good quality kids saddle.

SDG Fly Junior kids saddle!

Some of the features of this saddle.

It was not available in red to match the bike frame, nor all-black. Therefore I had to settle for orange colour.

Standard saddle construction with normal saddle rails.

Tough side material to prevent scuffing when the bike is rested against the ground or wall.

Comparing it to a standard adult road saddle.

Although it is shorter than the adult saddle, it can actually be even shorter and will still be fine.

Narrower to suit the kids' narrower sit bones. You will be surprised how many kids saddles are too wide.

Comparing the shape of the stock saddle (on the left) with the new saddle. Original saddle is even shorter.

Stock saddle has a large plastic bottom shell which matches with the stock seat post. This is what I meant by pipe-fitting interface.

Stock saddle has a cutout at the rear of the saddle, for an adult to hold the saddle using fingers when guiding the kid on the bike.

Stock saddle is chunkier as well, with a very thick and soft cushion.

As for the seat post, a standard 27.2 mm diameter seat post is needed. Since I already had the carbon handlebars, I might as well get a carbon seat post as well. There are many available online, but I decided to get one from Toseek which is of better quality. I'm not too concerned about the strength of these carbon seat posts, because it will only need to take a kid's weight and not an adult. Also, as long as you don't get the super lightweight type, the strength is usually more than sufficient as they will just use more carbon to ensure sufficient strength. The risk comes when you buy lightweight carbon parts from unknown sources.

New carbon seat post! Definitely needs to be cut to fit the kids bike frame.

Dual bolt top and bottom clamp, pretty standard stuff. However, the resting surface for the saddle rails is rather short as it is limited to the centre portion.

Standard bolt and clamp interface, similar to Litepro seatposts.

There is actually an open slot at one of the clamping areas, which is not such an ideal design. I did not notice this when I ordered the seat post.

Wall thickness is equal around the circumference, and more than thick enough.

Weighs 221 grams, which is decent but not really lightweight for a carbon seat post. That's perfectly fine as I don't need to worry about insufficient strength.

After measuring and cutting off almost 90 mm of seat post...

...the seat post weight is now reduced to 194 grams which is great.

New SDG Fly Junior saddle is 260 grams which is so-so. I expected it to be lighter as it is smaller than the usual adult saddles.

New saddle plus new seat post weighs 454 grams.

Stock seat post and saddle only weighs 254 grams! That is really very lightweight.

A lot of the seat post weight comes from the saddle clamp area, not the aluminium or carbon tube. Also, the steel saddle rails on the saddle accounts for a lot of the saddle weight as well. The stock seat post and saddle design eliminates both of these heavy components, which allowed it to save a lot of weight. However, this sacrifices the option of saddle adjustability. 

New saddle and seat post installed on the upgraded 3 speed kids bike! Unfortunately the orange saddle does not really match the red frame.

Finally we can adjust the saddle tilt angle...

...and also the fore/aft setting to optimize the pedaling ergonomics.

Overall, this seat post and saddle upgrade actually caused a 200 grams increase in weight, which is unusual. The better saddle quality and position adjustment comes at a cost of heavier weight.

Bestrider Pump Pro 16 (Single Speed)

5.6 kg without pedals and kickstand, in stock condition.

About 6 kg with larger Early Rider pedals (266 g) and kickstand (102 g).

Bestrider Pump Pro 16 (3 Speed)

After upgrading to 3 speed drivetrain, new SDG saddle and seat post.

- 6.6 kg without pedals and kickstand.

- 7.0 kg with Early Rider pedals (266 g) and kickstand (102 g).

At 7.0 kg for a 3 speed kids bike, I think it is a very good weight. Probably very difficult to go any lower unless you change to carbon wheels or carbon frame/fork.

Bestrider Pump Pro 16: Handlebar Area Modification

For the modification to the Bestrider Pump Pro 16, I will start from the handlebar area. The objective is to install a 3 speed internal hub drivetrain onto this bike. Why 3 speed? Because the shifting force for the 3 speed shifter is very light, which makes it well suited for kids.

First of all, I need to change out the stock handlebar which is ridiculously tall. From what I see, the stem position is OK, just that I need to change to a handlebar without such a big rise. At the same time, the handlebar should be narrower to match the narrower shoulders of a kid.

I have used Toseek flat handlebars on quite a few bikes. Namely, the Fnhon Gust, the Bike Friday Haul-A-Day, United Trifold, and the Fnhon DB11. These carbon handlebars are cheap and good, and available in a wide variety of widths. You can even choose between glossy or matte finishing.

This time, I got the same 480 mm width as what I used for the rear passenger of the Haul-A-Day cargo bike. I found that this handlebar width seems to be well suited for my kid.

I was not sure whether the flat type or the riser type would be more suitable, so I decided to get both and let him choose. The clamp diameter on the stem is 25.4 mm, not the larger 31.8 mm diameter.

Flat vs riser type Toseek carbon flat handlebar, 480 mm width.

Actual width is slightly longer than spec, but not an issue.

Flat bar is 85 grams.

Riser bar is slightly heavier at 92 grams.

Stock aluminium handlebar is a lot heavier at 223 grams, as it is also wider and taller.

The riser bar was chosen, here is how it looks on the bike.

Adjusting the handlebar rotation angle for the optimum rise and sweep.

The tricky part of using the 3 speed Revoshifter is that it takes up valuable space on the handlebar, and requires a shorter grip to match. This means some trial and error before finding the optimum solution.

3 speed Revoshifter for Nexus 3 speed internal hub, SL-3S41. Weighs 75 grams.

It uses a steel clamp band, which may cut into the carbon handlebar. Got to make sure I don't overtighten the Clamp Bolt.

Backtracking a bit, let's take a look at the stock rubber grips of the bike. A smaller grip diameter is better for kids as they have smaller hands. The easiest way to have a smaller grip diameter on a standard 22.2 mm diameter handlebar, is to use thinner rubber grips.

Stock grip outer diameter is less than 28 mm. This is smaller than the usual adult grips which is around 32 mm in diameter.

Stock grips are 64 grams for a pair.

Due to the relatively narrow handlebar (480 mm width), there is limited space on the handlebar to fit the grips, shifter and brake levers. Therefore, I need to make sure that the rubber grip length is not excessively long.

Stock grip length at the bottom, new short grip + Revoshifter grip at the top. Based on my kid's hand size, this length is sufficient.

I bought many different rubber grips of various brands and lengths, and tried to mix and match them to get a suitable set for the left and right side. This is the final set I used, at 58 grams.

On the left side with no shifter, I used an 85 mm grip, which is still shorter than an adult full length grip of 130 mm. Outer diameter is larger than stock at 31.2 mm.

On the right side with shifter, I used a super short 65 mm grip to match the Revoshifter grip. Diameter on the grip is 29.5 mm.

Diameter around the Revoshifter grip is large at 38.9 mm diameter. Hopefully it is not too big!

Here is how it looks with the rubber grip beside the Revoshifter grip. Just managed to fit the brake lever beside, without the lever bottoming out.

Just enough space to fit the grip, Revoshifter and brake lever.

On the left side, in order to ensure the same position relationship between the grip and the brake lever, a gap between the grip and brake lever is necessary.

On the left side, although I could have used a longer grip to close up the gap between the grip and the brake lever, I decided to maintain a short grip. This is to ensure that the hand position is resting correctly at the intended position for 1 or 2 finger braking, instead of sliding inwards towards the centre.

With this setup, it is necessary to use 1 or 2 finger braking, as the brake lever is too far away to put all 4 fingers on it. Hopefully this is OK as kids' hands are not as strong and I am not sure if the fingers are strong enough to apply the brakes effectively.

United Trifold: Assembly Begins

In my case, I am basically building a United Trifold from scratch, since I decided to upgrade nearly every part of the bike. From the bare frameset, I added the crankset, wheelset, seat post and handlebar, plus a totally new single speed drivetrain.

By doing so, I learnt a lot about this bike, both good and bad points. And this is just the start of the bike modification, there is lots more to come! It's definitely not the most cost effective way to build a bike, but it is fun. Besides, I bought this bike not because I really need it (I have many other bikes), but because I was curious to find out more about this type of trifold bikes. I used to have a Brompton M6R, but the upgrades were mainly cosmetic and functional, and not a total teardown like this one.

With my dream wheelset and basic drivetrain installed.

New carbon handlebar and Ergon grips installed, on the new Fnhon handlepost.

Single speed setup, with just one rear sprocket, and a new chain tensioner.

52T Stone narrow-wide chain ring on the non-series RS510 crankset.

Installing cables on a folding bike is always tricky, as you need to ensure that the cable slack is enough to enable folding and steering, and yet not leave too much slack as it can get in the way during folding. Sometimes it takes a lot of measurements, plus trial and error to make it work optimally.

Measuring the weight of the two brake inner cables before installation. There is no shifter cable for this single speed setup.

After cutting the excess cable off, here is the weight removed. This gives a total inner cable weight of 35 grams that is on the bike.

I added this SM-CB90 Brake Cable Adjuster to the brake outer casings, to release more cable when I need to open up the brake calipers more, during wheel removal.

I love the new 3D forged handlepost, with no welding at the joints. Also check out the new Litepro headset.

Here is how the handlebar looks with the brake cables connected! Super clean with no shifter cables.

It was tricky to find a suitable place for the inline SM-CB90 brake cable adjuster, as it needs to avoid areas with sharp bends, and also avoid being near the frame to avoid knocking sounds during riding or leaving scratches on it.

Litepro A62 seat post, with a new lightweight carbon saddle.

Here is the original Tektro caliper brakes, conditioned to work smoothly, and with new Ultegra brake pads.

Also using the stock Tektro brake calipers at the rear. Smooth cable routing is one of the factors for good braking performance.

Love the look of the wheelset, with the unique paired spoke pattern. Looks just as good as the Kinetix Pro wheelset on the Dahon MuEX.

Rear drivetrain completed! Drivetrain efficiency is at good as it gets, with a near-perfect chain line and no internal hub drag.

The ideal chain length is when the two pulleys are in line with the hub axle. (or is it the chain tensioner pivot?)

Single speed drivetrain, with one 14T sprocket on the standard freehub body.

The bike is almost ready for a test ride! There is a huge weight saving from the stock setup, it will be revealed in the next post.