JonF
Well-Known Member
I like to ride bikes. My kid like to ride bikes. Sometimes we ride bikes together, but i wish it were more often. I've had her on a Burley rear seat, and a Shotgun mid before she got proficient on her own pedal bike. Thing is, at almost 4 she doesn't have the legs to do a mild reservoir or trail ride like when i would be carrying her on my bike and I was really starting to miss the longer daddy/daughter adventure rides. With the gracious donation of this fine trailer bike by @mfennell i was hoping to change that and expand our riding sessions. But i grossly underestimated the size of the kids reach here. 😂
I measured the geo of her little Woom 2 and its a 14" pedal to seat height with tiny 80mm cranks. The bike trailer was over 20" with 140mm cranks so we have a LONG way to go...
Free mods.
You can slam the seat by trimming the seatpost for max insertion and flipping the old school seat clamp so it tucks under the rails. Boom, instant 1.5" reduction. Could likely drop another inch with a slimmer saddle or a bmx style but that would be the opposite of free so lets try some other things first.
A test.
First and foremost, NEVER buy these chintsy pedal blocks. Not only are they overpriced garbage (i feel swindled), but they create more problems than they solve. Pedals are flat for a reason and mostly that's stability. When your pedals are mostly cubes, they want to roll underfoot like trying to balance on a lumpy log floating on the pond and you constantly slip right off. Still, it taught me 2 things: 1. the added inch in pedal height still wasn't enough, 2. think twice about this as seen on tv kinda BS. Back to the drawing board...
Fabrication.
Old school, 1 piece CroMo bmx cranks have a lot of downsides, but they also have one good thing going for them: weldability. With some spare 1/2" stock, i cut, drilled and shaped a pedal mounting boss to weld to the crank arms. With the cranks being 140mm native, i whipped up these with spacing that would go as low as the Woom 80mm and an in-between 110mm (all 30mm apart). The thought is that we can start on the shortest setting and progress through, that is if we still have any interest (you know kids...). I even opted to attach them on the leading face of the crank arms to better handle the massive watts a wee child generates on the power stroke.
The Issue.
I'll stop right here and let you contemplate my folly. Go ahead, i'll wait. Yep, thats right, welding that pedal boss completely blocks all the bottom bracket hardware from ever going on (or off for that matter) so time to rethink this. I decided that i had way too much time already invested and we were doing this no matter what so i would have to pop off the boss, completely reassemble the cranks and weld them on the bike rather than on the fixture table. Luckily the broken tack welds served as alignment locators so i could easily clamp and weld them off the table. It's certainly commitment but you can still disassemble enough to clean/grease the bearings (And lets face it, ain't nobody putting hard miles on this contraption).
Options.
With it fully welded out and holes tapped, its almost time to ride (if it would ever stop raining). Not sure if the protruding section of the crank will be an ankle biter when the pedals are mounted in the shortest position and the cranks swing around, but maybe wrapping some sort of padding around it might help. Hopefully the pedals stick out far enough it doesn't matter but little kid's Q-Factor's aren't much so i might need a solution there. Just need to get that left hand tap for the other side and hit it with some paint and i think she'll be GTG!
A final note, i am doign this mainly so she has a stable place to put her feet without the frustration of her feet slipping off and the danger of dangling feet. I dont really expect her to add any appreciable forward momentum to our 1-ton bike train with her small stature, short cranks and the dubious gearing ratio of this trailer (just look at that 40t chainring), but if she can at least feel like she is participating, thats a win!
I measured the geo of her little Woom 2 and its a 14" pedal to seat height with tiny 80mm cranks. The bike trailer was over 20" with 140mm cranks so we have a LONG way to go...
Free mods.
You can slam the seat by trimming the seatpost for max insertion and flipping the old school seat clamp so it tucks under the rails. Boom, instant 1.5" reduction. Could likely drop another inch with a slimmer saddle or a bmx style but that would be the opposite of free so lets try some other things first.
A test.
First and foremost, NEVER buy these chintsy pedal blocks. Not only are they overpriced garbage (i feel swindled), but they create more problems than they solve. Pedals are flat for a reason and mostly that's stability. When your pedals are mostly cubes, they want to roll underfoot like trying to balance on a lumpy log floating on the pond and you constantly slip right off. Still, it taught me 2 things: 1. the added inch in pedal height still wasn't enough, 2. think twice about this as seen on tv kinda BS. Back to the drawing board...
Fabrication.
Old school, 1 piece CroMo bmx cranks have a lot of downsides, but they also have one good thing going for them: weldability. With some spare 1/2" stock, i cut, drilled and shaped a pedal mounting boss to weld to the crank arms. With the cranks being 140mm native, i whipped up these with spacing that would go as low as the Woom 80mm and an in-between 110mm (all 30mm apart). The thought is that we can start on the shortest setting and progress through, that is if we still have any interest (you know kids...). I even opted to attach them on the leading face of the crank arms to better handle the massive watts a wee child generates on the power stroke.
The Issue.
I'll stop right here and let you contemplate my folly. Go ahead, i'll wait. Yep, thats right, welding that pedal boss completely blocks all the bottom bracket hardware from ever going on (or off for that matter) so time to rethink this. I decided that i had way too much time already invested and we were doing this no matter what so i would have to pop off the boss, completely reassemble the cranks and weld them on the bike rather than on the fixture table. Luckily the broken tack welds served as alignment locators so i could easily clamp and weld them off the table. It's certainly commitment but you can still disassemble enough to clean/grease the bearings (And lets face it, ain't nobody putting hard miles on this contraption).
Options.
With it fully welded out and holes tapped, its almost time to ride (if it would ever stop raining). Not sure if the protruding section of the crank will be an ankle biter when the pedals are mounted in the shortest position and the cranks swing around, but maybe wrapping some sort of padding around it might help. Hopefully the pedals stick out far enough it doesn't matter but little kid's Q-Factor's aren't much so i might need a solution there. Just need to get that left hand tap for the other side and hit it with some paint and i think she'll be GTG!
A final note, i am doign this mainly so she has a stable place to put her feet without the frustration of her feet slipping off and the danger of dangling feet. I dont really expect her to add any appreciable forward momentum to our 1-ton bike train with her small stature, short cranks and the dubious gearing ratio of this trailer (just look at that 40t chainring), but if she can at least feel like she is participating, thats a win!
