Monday, 22 October 2012

Shrinky Dink kinderfat build

Remember Shrinky Dinks from the 70's and 80's? (I think they may have made a recent re-emergence) if not - let's refresh: they were these things you'd get mum to put in the hot oven, and they'd shrink to a quarter or less of their original size.

Great fun as a kid, but then you got confident with your new found knowledge of thermoplastic polymerisation and tried shrinking other things when mum wasn't looking, like your little brothers GI Joe action figures or dad's new digital watch. After that, mums choc-chip cookies never tasted the same and dad never needed his watch to know that it was time for a whippin...

The pet monkey is almost 7 now, can you believe it? She has a long and varied history of  riding adventures with us, from the early days of the Weeride on the Baby AC, to the tandem with a Weeride, then up to a LOCT on the Baby AC and the Moonlander, and just recently the mini half fat tagalong. In between she had her own 12" Malvern Star, as well as a 16" MissyGoose from my old mate X, and a recumbent tagalong called the iGo by Weehoo. Bombing down singletrack on the Weeride at speeds that wifey is better off not knowing about, all day riding trips into town, multiday tours on the tandem - the monkey was my little riding buddy. Plus the times I had to pick her up from daycare and she would sit on top of the loaded BOB trailer, I even had a donkey trailer that I'd tow out to the folks place, loaded with Xmas pressies, then tow the kids around the paddock on it as a human powered hayride... Ahh, the memories remain long after the scars have healed.

Times change, her widdle wegs are getting wonger and stwonger, sadly she barely fits on the bikes with me any more (well, until I get that kiddy stoker tandem kit) so time to extend her range with a new bike. In my profession, I specify and build a lot of custom high end products for clients, to suit their particular requirements and tastes. Why should a build for our daughter be any different?

Okay, so shes only 7 and doesn't need polished titanium or Di2, but she does need gears and a lightweight frame. All of her bikes have had coaster brakes, so no need to change this either. She's not ready for a full mtb, 20" is her next progression, but it must be a do anything bike to suit our active family lifestyle. So, fellow bicycle enthusiasts, come on a journey down the bikepath of shrinky dink custom builds with me...

We start with a couple of  fairly innocuous boxes.

Contained within is a Radius Neo 20" girls bike. Alloy frame, alloy fork, slick tyres. Pet monkey gets involved in the first stage of the build - the unpacking and removal of the birthday wrapping.

Daddy-daughter projects are great. She's quite clever at thinking out of the box too, she asked me the other day if the grease gun would work to stop the coins from clinking around in mummys' purse. As funny as that might sound initially, it would be me who ends up cleaning it up.

Don't send me emails or hate comments on this one. I KNOW YOU SHOULDN'T USE A CONE SPANNER AS A PEDAL SPANNER. But really, can a 7 year old safely wield the hefty PW-4?

'Daddy, how do I know when the stem clamp bolts get to 8Nm?'

Alright, I can hear the yawns, the tedium of building a kids bike is getting to some. So, lets change gears, metaphorically, in the build.

There are kids bikes out there with 18 gears. Seriously, can you imagine trying to explain the shift pattern of a gearchart, logic of gear inches, triples and cross-chaining trim to someone who has just learnt to tie their own shoelaces? There are adults that struggle to master shift patterns on their bikes.  Bike makers - get with the program - KISS principle for kiddies. 3 gears and a coaster.

Not shown here is a) the twisty (shifter) that I ordered later to make shifting easier, and b) the pet monkey, past her bedtime and as the old saying goes 'when you get drowsy, your work gets lousy'... and there was no way she could finish her 3rd Red Bull either.

The hub only came in silver. Why a Sturmey? The frame O.L.D. (Over Locknut Dimension - as in width between frame dropouts) was 120mm, most other internally geared hubs (IGH) are 135mm and the OLD of the Sturmey was 120mm. Also came in 36 hole, whereas other 3sp options (from Aussie distributors anyway) were only 32H. Why did that matter? Well, they needed to match these:

Ah, so now you're interested again. The rims are Kris Holm 19" municycle rims, double walled and eyeletted, 47mm wide - designed for unicycle trials. The tyres are Nimbus CyoLites, again from a trials background.

But as I said, the hub only came in silver, so it had to be painted to match my build spec. Mask, etch and colour:

Velocity Wheels are just up the road a bit, now I've gotta praise their awesome service. I ordered 80 custom cut/rolled 14g spokes, black nipples and a 36H sealed bearing high flange track hub at 2:30pm Thursday arvo - the lot was waiting for me at work first thing on Friday morning.

The frame and fork is alloy, but what I found was that it had a steel steerer. Well at least I didn't need to rustproof the frame, just the steerer. Same rustproofing cavity wax as I put in my Moonlander build and wifeys Pugsley build.

Added some electrical tape over the drilled bolt holes, and a rubber bung to keep out most debris, these are available at many auto stores - or grab a  handful out of the floorpans next time you're spending quality time at your local 4x4 wreckers. C'mon, admit it, I'm not the only bloke who enjoys wrenching on bikes and my 4x4...

Now lets talk bearings. You don't exactly get Phil Wood or Chris King quality as OEM on a bike this level, however you can alter a few things to help get a bit more longevity out of what's there. Run what you brung. The BB/crank is a basic one piece with a very open bearing setup, not much you can do except pump in grease as a barrier, overpack it baby. In time I'll replace it with some nice lightweight 3-piece cranks.

Headset - sure, overpack as well, but customise the sealing.

Shown here on the lower bearing cup and fork crown, a large zip tie to provide a seal shoulder, then 2 o-rings to cover the void between cup and fork crown race. Add a similar o-ring to the top bearing race and you've got a very well sealed headset.

Back to the wheels. It's a very relaxing time building wheels in the workshop, the family has gone to bed and all is silent in suburbia, apart from the possums fighting over the leftover bananas in the tree next to the shed.

By now you're probably starting to get the picture about this bike. Yeah, I could put in an Alfine 11 with Di2 but no, I wanted it to be a bit of a sleeper, not like that image that circulated a few years ago of the small child on the start line of a local triathlon, on a Cervelo with Lightweights. Nothing fancy to see here, move along. Seriously though, we wanted her to have a bike that performed well and she could take pride in, be reliable in harsh conditions and survive our adventures.

Has the penny dropped yet? She needed a fatbike. A shrinky dink fatbike to match wifeys white Pugsley.

To make this happen I needed several things:
  1. Frame that could accept fat profile tyre/rim combos.
  2. Fat tyres relative to scale of aforementioned shrunken bicycle.
  3. Fat drilled rims to look phat and mount fat tyres.
  4. Riser handlebars to mount cute wicker basket, to carry flowers and french breadsticks in.
This last option was a priority - a pet monkey that has just learned how to tie shoelaces doesn't know much about the 67-387 ETRTO sizing for her tyres - but if that bike didn't have a pretty basket on it there was no way it would ever be ridden.

The rims are drilled for weight reduction, DIY rimtape once again. I have all sorts of vinyl and polyester signwriting material left over from previous projects, I had a roll of 50mm white and 50mm clear. Cut oversize to suit the rim OD.

Then laminate together, leaving a segment to overlap and create the join:

Trim the laminate to suit the required width, install on rim, pull tight and join at overlap:

Cut a valve hole, install tyre & tube.Before installing the wheels there were a few things to do, rustproof the steel axle locknuts with some cavity wax, and grease all threads. With coin grease (shhh, don't tell wifey)

The front brake had to come off, the brake pads didn't line up with the rim braking track, also the monkey doesn't use the front hand brake on her other bikes. Removed the V-brake posts and plugged the holes with some rubber bungs, probably from an '89 Hilux.

Fatter than stockos:

The shift cable and chain is covered by this neat guard:

The control panel is basic and uncomplicated, I stripped the shifter down and greased it up, to make the shifting light for a little hand. I had some twisty width grips in my spares bin as well as some old lock on rings to keep it all in place.

On her first test ride, she found the gears a boon to tackle climbs she'd previously walk up. The tyres give a reasonable amount of suspension and plenty of traction.

Only bit of beach we could find in the city was the strip underneath the Story Bridge, it would have to do as a test until we get over to Moreton again...

This is basically stage 1 of the build, with a rack and bag system to go on to extend her carrying abilities. Seat is initially low so she can get the feel of the bike and both feet flat on the ground.

 She calls it her 'anything bike', to match her 'anything boots' (Keens). To my mind though, she is the one who can do anything she sets her mind to. 

Next weekend we'll take it out to a real beach.


  1. absolutely AWESOME!!!!!!

    the wife and I need to get ourselves one of them pet monkeys to build a bike for...

  2. Dude that kinderfat-bike is awesome! i just read your whole trip of Moreton fat-bike adventure with the family. I thought it was great, also just found your blog today and I dig it. I would love to ride stuff like that but I'm half a world away, i'll just have to follow along and pretend.Look forward to reading/seeing more later, DR

  3. Absolutely superb...Great post and super images...
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    I am looking forward to checking out your next posting...

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