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.
No comments:
Post a Comment
Every comment is moderated before publishing due to spam bots. If you don't see your comment yet, it is likely that it is currently being reviewed. Thank you for your patience!