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Hans Lellelid
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Project Mjölnir - 20" Kids Bike
This build report actually predates my older son's Raleigh RX 24 build , but it was a more extensive build (and finished more recently), so it's getting published a bit out of order. Since I'm both happy with my bikes and have no room for anything additiona...
Project Mjölnir - 20" Kids Bike
Project Mjölnir - 20" Kids Bike
snakesthatbite.blogspot.com
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Project Mjölnir - 20" Kids Bike
This build report actually predates my older son's Raleigh RX 24 build , but it was a more extensive build (and finished more recently), so it's getting published a bit out of order. Since I'm both happy with my bikes and have no room for anything additiona...
Project Mjölnir - 20" Kids Bike
Project Mjölnir - 20" Kids Bike
snakesthatbite.blogspot.com
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Well, we're skipping ahead a bit here, but the build is finished!

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5/28/18
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Raleigh RX24 - 24" Kids Road/CX Bike Project
Constraints breed creativity.  Or so they say.  Well, my bike storage is quite constrained.  And there are these growing kids with bigger and bigger bikes -- and expectations that they get to share that limited space.  So, while being constrained to 3 bikes...
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To make this frame last longer, I decided early on I'd build it with 2 weelsets. The 20" (406) for which the frame is designed, and also a set of 16" -- though I went with the 349 ETRTO size, typically used on recumbents -- not the more-common 16" BMX (305 ETRTO). Sizing up a bit, since I don't need them that small -- and hopefully these will look less out-of-place in the frame. We shall see.

Because of how the holes are offset on one side of the hub vs. the other, using every other hole is actually less trivial than it sounds. It requires 3 spoke lengths. I chose the NDS as the side that would get the uncompensated length and then for the DS I adjusted the cross "factor" by 0.125 (i.e. I used a 1.0-0.125x for one set of spokes and 1.0+0.125x for the other). I thought I had a paper-napkin sketch that made this make sense, but I think maybe the correct adjustment would have been 0.25. If the wheels were for me, I probably would have replaced them as half of the DS spokes might not really be long enough, but since it's for a 40lb kid, I'm not going to worry about it.

I played around with the lacing a bit -- usually alternating sides, but since this is 1x lacing, you can also do either all heads-in or heads-out. I did the front DS heads-out, for no particular reason. (Mostly just with such tiny rims, I didn't see any reason to move the spokes further outboard, since the bracing angle is already pretty extreme.)

These are straight-gauge (2.0mm) titanium spokes in gold. I splurged a bit on these $2 spokes, since I was only ordering 32. (This also made me less likely to correct the minor spoke length issue.) Red Sapim Polyax aluminum nipples. I used motor oil as lubricant, as usual, but wondered if ti spokes might need anti-seize. Too late! They're properly tensioned, though, so I don't expect to ever need to adjust them.

The spoke sizes made this a fun project. Too bad I failed to get that part right. I clearly need to dust off my trigonometry.
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12/25/17
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For the 20" (406) wheels, I ordered a set of Spank Spoon 28 rims in 32h drilling. I would have much preferred to find 24h drilling, as 32his way overkill for a wheel this size, but as this is a bmx wheel size, it is very difficult to find anything less than 32h -- and even 32h is far less common than 36h.

But, to solve this problem, I decided to go with 32h rims and hubs and just use half as many spokes, since 16 is also a nice divisible-by-4 number. The only challenge using half as many spokes presents is lacing and what to do with the extra holes. More on that in a bit.

For the hubs, BDOP has been having a sale on some old stock Novatec hubs. For this frame I need 130mm rear spacing and disc hubs; that's a bit of a unicorn now that the standard settled on 135 OLD for disc, so it is lucky that the D352 hub was available in that clearance bin. For front I got the excellent, but discontinued, D711 QR hub. I really like Novatec hubs, so picking these up for $80, per set (with Japanese bearings) was a great deal. I bought 2 sets ... more on that later.

In order to ensure that I wasn't lacing spokes from one side of hub to holes angled for the other side of the hub, I opted for a paired-spoke lacing. I was inspired by -- and followed the directions -- described here:

http://faqload.com/faqs/bicycle-components/wheels-and-tyres/paired-spoke-lacing

(There is actually a nds/ds-reversed mistake in the lacing instructions; I need to email the author to suggest correcting it.)

I used Sapim Laser spokes. Those spokes can be cut as short as 175mm, which worked for this build (I think my shortest length was 177mm).

To fill in the holes (to keep out dirt, water, etc.) I used 5mm plastic plugs for furniture, etc. This idea was also not original, I read about it first here:

http://forums.mtbr.com/fat-bikes/filling-those-unused-spoke-holes-rims-860362.html
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12/23/17
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The first step in the project was just stripping it down to the frame. Any parts that seem viable we'll donate to a local bike charity; the frame is all I really plan to use from this.

The unmodified frame weighed in at 1588g (3.5lbs), which is not very light (it weighs almost as much as my 59cm titanium gravel frame), but it seems nicely built and it'll weigh a little less when we're done with it.

The plans for this project:
- Disc brakes for ultimate stopping
- Wide range gears for MTB (and our neighborhood hills)
- Lighten it up! -- Arbitrarily, I'm shooting for sub 15lbs, but I haven't really done the calculations to see how reasonable that will be.

After stripping off the components, my friend Kurt helped me finish what I started with a Dremel; we ground off the brake bosses (we're going disc brakes here, so those are useless) and kickstand plate.

Sorry, kids; no, you can't have a kickstand on your bike.
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12/15/17
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Since I'm both happy with my bikes and have no room for anything additional, I've decided to have some fun with the next bike for my [recently-turned] 4yo. He's currently riding an Isla CNOC 14, which is great, but having gears is a complete game changer.

This project wasn't really something I was looking for. But someone down the street decided to throw away a Scott Scale 20 kids bike ... and so it begins.

Anything steel has rusted out. The fork is terrible (and putting a fork on a kids bike is ridiculous). And it must weigh 30lbs. But the frame seems decent. THe specs are nice. We can fix this.
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New bike (frame) day!

Loving this frame by Waltly Ti. http://waltlytitanium.com/

Tapered HT. Thru axle. Fender and rack mounts. Clearance for ~45mm tires.
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Waltly Titanium Coupler Travel Bike
Well, I knew it'd be only a matter of time. The Justification I have an opportunity to do some travel where I'd want to have a bike, the duration would be too long to afford renting a bike, and to much of a logistics nightmare to take a full-size bike box. ...
Waltly Titanium Coupler Travel Bike
Waltly Titanium Coupler Travel Bike
snakesthatbite.blogspot.com
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