This is what AUD$260 delivered from Chain Reaction Cycles gets you - a 13kg full suspension kids bike:
I'm hoping this bike will form the basis for a great kids bike and with some upgrades along the way hope to see the weight in the 10-11kg range.
For a sub $300 FS bike I wasn't expecting much from the suspension but I have been pleasantly surprised. The suspension is a fairly standard 4 bar link setup with coil shock and Suntour fork on the front. Spring rates are amazingly good for a 30kg junior rider. The suspension not only works, it works surprisingly well. What is crap (but to be expected at this price point) is that the forks and shock are heavy and offer no adjustment.
Rear travel is around 70mm and front travel seems to be around 50mm.
The Suntour front fork has a long axle to crown distance so the front of the frame seems like it is quite jacked up. The axle to crown distance on this 24" 50mm fork is only about 20mm less than the axle to crown on a Fox F100RL 26" fork. This is probably just a 26" fork with the bosses welded 1" lower. The fork is also quite heavy at 2079g.
I'll be swapping the forks for a set of Rockshox Mag21's with about 60mm travel. I just need to finish machining up the brake boss adapters. This should drop about 600g. I'll also be swapping out the rear shock for a Fox RP3 that I currently have spare. The stock coil shock weights 410g and the Fox RP3 comes in at 209g, so a further 200g weight saving there. The rear shock is 165mm eye to eye and 38mm stroke. This is the same as the shocks on Giant ATX and Anthem X frames. Putting air sprung forks and shocks on should give me plenty of adjustability to get things nicely dialed in.
I've ditched the stock cranks in favour of a set of Sugino 152mm triple cranks. For this setup I did not need the 50t big ring, so I reconfigured it for a double chainring. This makes it plenty fast enough for junior riders and removing the big ring saves another 112g. Total weight loss by replacing the cranks was 342g.
I also replaced the Tourney rear derailleur (370g) with an old XT rear derailleur (240g).
I was thinking about swapping out the 7 speed cluster but it looks like it is the type with integrated free-hub (screw on type), so I'd need to lace a new hub on the rear wheel to be able to get any serious weight savings going there.
Pedals: stock items are plastic and heavy - 314g for the set. Wellgo make some nice aluminium pedals (M111) that are less than US$20 on ebay and weigh a claimed 240g (maybe lighter if this weight includes the reflectors). These pedals look nice and rounded on the outside - something to consider for safety's sake on a kids bike.
The stock Maxxis 24 x 1.75 tyres are heavy at 730g each. The tread pattern doesn't look too single track worthy so I replaced them with a set of Continental Explorer 24 x 1.75 (650g each). The Conti's are not exactly a lightweight tyre but the grip offroad is great, they have good strong sidewalls and seem fairly puncture resistant. The price is also right at around AUS$13 each at chainreactioncycles .
The ultimate tyres in the 24" size seem to be the Schwalbe Moe Joes. The weight is reported to be 330g per tyre, so by replacing both tyres and using light tubes you could save almost 1kg in weight - and rotating weight at that! These tyres are definitely a possible future upgrade option although they are seriously expensive at around US$60 each.
The stock 27.8mm seatpost weighs 326g and the seat another 321g. Swapping these out for a spare 27.2 seatpost (240g) using a "coke-can" shim and a Fizik Tundra saddle (257g) shaved off another 150g.
The standard stem was also a little long for my daugther (207g), so I replaced it with a 50mm AM stem that I had (160g). It is surprisingly difficult to get a short stem that is light. All the short stems seem to be over-built for freeride/downhill use. The guys at carboncycles.cc seem to have reasonably priced light stems. I haven't bought anything from them so don't know what they are like to deal with or what the quality is like.
I haven't got around to weighing the bars but they are probably heavy items, so possibly around the 300g mark. There's a good 150g of weight to be saved here.
If you've got some decent parts lying around its possible to get this bike down to about 10.5kg or about 23lbs. That's not bad for a full suspension kids MTB. If you had to buy all of the bits new it would probably be a fairly expensive exercise, although still probably less than buying something like a Scott Scale RC Junior (which would probably be well over $1000 - maybe over $1500 here downunder).
Current weight is 11.5kg (about 25 pounds) but I've got a Fox RP3 rear shock to go on (some custom bushings needed) which will lose about 200g and once the current tyres are worn out I'll get a set of Schwalbe Moe Joes which with some lighter tubes may lose another 600g. So that may get it down to around 10.7kg.
I've been really fortunate to have a whole bunch of parts that I could use, so the total expenditure to get it to 11.5kg has been:
|Total Expenditure (AUS $)||$490.00|
Total weight loss to date is 1819g. Bike ready to ride is now 11.2kg.
Total weight loss to date is now 2482g. Bike ready to ride is now a touch under 10.5kg.
|Total Expenditure (AUS $)||$589.00|
I wanted to stick to a AUD$500 budget but I couldn't resist getting a set of Moe Joes. At the end of the day, my daughter has finished up with a bike she absolutely loves to ride. It is relatively light but also really functional. The suspension works really well for her weight, the tyres provide great hook-up and the gear range is ideal for the single track where we ride and the bike path cruise to get there.
Had a new rear wheel built so I could use a cassette rear cluster instead of the uber-heavy freewheel. This allowed us to run a 9 speed 11-34 cassette which gave a much wider range of gears than the original 14-28 cluster. This meant that I could change the bike to 1x9 and still retain the same gear range as with the previous double ring front setup which had been working really well.
Net result was about another 300g lost.
Good kids bikes are a very rare thing. Scott make some nice hardtail and full suspension bikes, but the cost in Australia is extremely high. I'm not even sure that you can buy the Scott Spark RC JR 24 in Australia but the cheapest I could find it online was $1230 (discounted from $1700!!!) plus $158 delivery from Evans Cycles. By the time you pay import duty on it you're looking at around $1600-$1700 for a kids bike with a claimed weight of 24.82lb (11.2kg). Even the budget Scott Spark JR is $700.
With that in mind, if you can get a good, cheap bike as a starting point and if you've got some spare parts you can re-use, then its well worth spending some time in the shed and putting together your own bike, especially if you can involve your kids in the process.
|BB shell width||68mm|
This bike is now my youngest daughter's and so it's undergone some customisation to suit her: