2.5kg for AUD$350 - Kids bike weightloss

This article is all about taking a 13kg $200 kids bike and getting it on a diet without spending stupid amounts of money.

Why bother?

If you're kid doesn't do alot of riding, or rides mostly around on the flat, it doesn't matter what their bike weighs (within reason).

If you take your kid offroad and up and down mountains then you want to get the weight down. There is a massive difference for a 35kg kid between a bike that weighs 13kg and one that weighs 10kg. 3kg doesn't sound like much but it is.

Principles

Use what you've got

See what spares you've got from full sized bikes that you can use. Lots of it will work on a kids bike and if you've got it already its free. Also, ask your mates. They've probably got some stuff just lying around you can have. V-brakes, 8 speed shifters, semi-worn cassettes, 25.4mm bars... its all good for kids bikes.

See what you can get cheap

Ask at your local bike store ("LBS") for old stuff they may be throwing out. For example, no one wants old forks with limited travel, but these will be perfect for use on a kids bike - take a look at the Mag21's I tuned up.

Spend your money wisely

Spending money on a kids bike is a real balancing act. Kids grow quickly and before you know it they need a new bike. You can also pretty much count on never getting any money back if you sell a kids bike. There are very few people prepared to pay for a good kids bike. Bottom line, you want to spend as little as possible.

So, with this in mind, you want to spend as little money as possible unless you're buying a component you can use on the next bike. For example, a good light set of handlebars can be used from the age of 6 to 60. The sort of components in the "re-use category no matter how old you kid gets" includes bars, stems, shifters and rear derailleurs. You may be able to re-use seat posts, bottom brackets, front derailleurs, brakes and forks but this really depends on what the next bike is.

2.5kg for $350

Well almost. Actually AUD$354 for 2479g off.

Here's the breakdown:

AreaWeightloss Cost
Cockpit496g $94.00
Drivetrain561g $166.47
Tyres/Tubes610g $85.80
Suspension812g $0
Totals2479g $346.27

Wheels/Tyres

ItemModelWeight (g)FromWeight Savings (g) Cost (AUD$)
Front TyreMoe Joe425chainreactioncycles305 $42.90
Rear TyreMoe Joe425chainreactioncycles305 $42.90
Totals 610g $85.80

Suspension

ItemModelWeight (g)FromWeight Savings (g) Cost (AUD$)
ForkRockshox Mag 211468dumpster611N/A
Rear shockFox RP3209spare201N/A
Totals 812g $-

Cockpit

ItemModelWeight (g)FromWeight Savings (g) Cost (AUD$)
StemMeta F Stem108carboncycles.ccc 99 $35.00
HandlebarsExotic 25.4mm aluminium handlebars176carboncycles.ccc210 $25.00
SeatpostXTC 400mm240ebay86 $32.00
SeatFizik Tundra257spare64 N/A
Seat clampAmoeba 31.921torpedo737 $4.00
Totals 496g $96.00

Drivetrain

ItemModelWeight (g)FromWeight Savings (g) Cost (AUD$)
Front DerailleurShimano LX145cambriabike12 $18.82
Rear Derailleur Shimano XT 240spare130N/A
Crankset Sugino 599ebay345 $110.00
Pedals Wellgo M111 120ebay74 $37.65
Totals 561g $166.47

Your cheating...

Almost 2.5kg for AUD$350 is a bit of stretch because I was able to lose 812g without spending a penny - I found the Mag 21's attached to a 95 GT in a rubbish skip and I had the Fox RP3 spare from an old Giant ATX 990 frame. If you had to buy these items second hand then you'll probably be up for another $150 or so. Still, losing almost 2.5kg for AUD$500 is pretty good, particularly when you consider that any good stuff you buy can be re-used in your next build. I plan to reuse the bars, stem, seat, seatpost, seat clamp, derailleurs, cranks, pedals and shifters to build a 26" MTB when my daughters have out-grown the 24". About the only thing you can't use on a bigger bike are the tyres and tubes.

More weight loss

Even though the bike is now down to just above 10kg, there is still alot of heavy stuff that could be ditched if the opportunity arises:

  • the tubes I'm using weight about 150g each - so some ultralight tubes might save some weight. I might give a ghetto-tubeless setup a go.
  • the bottom bracket is heavy and crap - replacing it with a nice square taper Ti one would be sweet but costly - probably 200g could be saved here;
  • the rear cassette is a 7spd screw on type which again weighs a ton, but I can't replace it with anything lighter unless I have I replace the rear hub with a freehub type hub. This is potentially alot of work for me or expense down at the bike store (particularly if the new hub needs all new spokes). A new hub and light cassette could save another 200-300g;
  • the front hub is heavy (and crap), but replacing it will probably cost serious $$$. Potentially another 100g to be saved here though.

I'd probably replace the bottom bracket if I could find a Ti one cheap somewhere (ie <$50) but that probably isn't going to happen any time soon.

As for the wheels and cassette, there' serious weight to be lost but it'll also come at serious cost. The wheels will also be useless in future when my girls are on 26" bikes.

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Frame