Kids 24" build project

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steve24

Likes Bikes and Dirt
My Daughter has outgrown her micro BMX and it's skinny tires are not great for MTB tracks so I have finally decided on a 24" for her next bike and would like to have it finished for her birthday in 2 weeks (might be a bit optimistic....).


As there seems to be a bit of interest in kids builds I thought I would do a build thread.

Started off with an Avanti Black Thunder- 8sp disc, stock weight a slim 13.7kg, bought used from a member on here.

The plan is to go 1x9 and use a heap of bits I had and I also got a heap of 24"goodies from SummitFever, light air fork, front wheel, cranks and more....


DSCF1724 (2) (800x600).jpg
 
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steve24

Likes Bikes and Dirt
1st step was to strip the bike and see were in hell 13.7 kg could be hiding on such a little bike. I am sure everyone else has wondered the same thing.....

Complete bike 13.7kg

Stock/ Swap to
frame, headset, square taper BB, 2.17kg -I might look for a Ti BB??

rear wheel complete 2.65kg -should be a chunk to remove here....[HR][/HR]


bare rear wheel, with Deore 6bolt hub 1127g ?????

cass 11-30 413g -used XTR 9 speed 11-34

tire 720g -used MoJoes 440g each (I hope I can run tubeless)

Tube 160g

160mm disc rotor and bolts 156g -used 140mm ashima rotor and ti bolts 70g

rear skewer 87g -used bolt up 37g

85mm stem 25.4 261g -used Syntace 102g

bar 580 wide 311g -used carbon with damaged ends I will cut off 122g

FD 200g -not needed

front shifter 130g -not needed

pedals 563g -thanks SF 237g pr

saddle/ post 638g -BMX micro saddle/ post 240g (need to get a reducer sleeve).

triple crank (no BB) 885g =thanks SF shortened LX 5 bolt 440g with single ring

RD Deore 291g -used X0 med cage 185g


front wheel complete 2kg -I hope to run a non disc wheel from SF 595g + 440g tire

fork 1812g - I hope to run an air Vbrake fk from SF 1717g with brake+ lever

front cable disc brake with lever 355g -as above

stock sterer spacers + bolt 48g

grips 55g -foamies or bar tape

chain 308g

rear cable disc 380g -juicy ultimate

seat clam QR 46g -bolt up 20g

So from a rough calculation I can drop about 4.2kg, to end up about 9.5kg.

Problem No. 1 - air fork from SF if 15-20mm too short (only have 20mm of steerer tube showing....). As the steer tube is steel I will look into a short extension....

Also wondering if I can drop 500g off the rear wheel????
 
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SummitFever

Eats Squid
What rims are those? If they are fairly lightweight (like around 400g) then you could look to rebuild the rear with a lightweight hub and only 16 spokes in paired spoke lacing.
 
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steve24

Likes Bikes and Dirt
Today have been thinking about using an old 28mm SID and keeping the disc front.
I have one and it looks like it should work if I reduce the travel to 63mm (from 90) to get closer to stock AC length.

I might strip one of the stock wheels to check the rim weight and rebuild with some Sapim lasers on Rotaz or circus monkey hubs, also have a DT240 front spare I could use.
If the rim is too heavy I will try and source another Aeroheat and rebuild the rim brake wheel I bought from SF....

I ordered a new BB today as well as a steerer extender from Wiggle. Stock BB is a piece of steel with a few balls on either side. Rough as and no seals....

She says she wants a bike that is purple with pink swirls. So there may be some colour change too. She hasn't seen the bike yet but I might get her to help with the rebuild???
 
moorey

moorey

call me Mia
Could a clever man like SF breathe life into some tired 80mm manitou scarabs? Bit of stanchion wear, but they are light and pretty short A2C height.
Free if you want to have a play with them.
 
John U

John U

MTB Precision
Bit of a grave dig but I have a suggestion Steve, keep the front disc and make it hydraulic. So much more stopping power with less effort. It'll make a huge difference if you're riding down anything steep and teach the correct technique (keeping bum over the back wheel).
 
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steve24

Likes Bikes and Dirt
Phase 1 was ready for her birthday in Feb. with weight under 10kg.

I will put up some up dates when I get a few minutes.
 
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schwing

Likes Dirt
impressive weight drop! nearly 4kgs.
that as a percentage of the bike weight is what, nearly 25% - scanning for ideas xmas
 
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