Kids 24" Full suspension build

Yakboy

So, a first time poster here but I have been lurking here for years but never had anything to contribute until now so here goes.

My 9 year old daughter is getting too big for her 20" mountain bike so I have been looking around for a 24" replacement but have not been liking what I see.

Her 20" bike was Giant with v brakes and spring front suspension (RST Capa's with the lighter springs) and after careful buying from E-bay and retrobike I managed to drop 3 kilo's from it's weight and changed the front chainring from a 42T to a 34T so in combination with a standard shimano 7 speed rear she had usable gears for the type of riding we do.

We are 25 minutes door to car park from Dalby forest so I ride weeknights and weekends are reserved for family rides (mainly the green routes with a little red and black thrown in occasionally)
My daughter is gaining good skills but as yet has not the stamina.

So...(I hope you are following this)...her next step up is to 24" (I think it will be at least 3 years until she needs a 26") and I would like a full suspension bike with discs. I know a lot of the Isla bike brigade will say kids of that age need no suspension at all but I disagree...tell that to my daughter as her arms are taking a battering over some of the more stony sections of Dalby. I don't see why I should be on a full suspension bike and she not...

So I start looking around and all I can find in the sub £500 bracket are heavy bikes with woeful spring front suspension and V brakes...sure they have flashy graphics and have "cube", "focus" or "scott" decals on them but they will not cut the mustard with my daughter.

So I look at some of the build threads on here and other forums and there are other people who have built up decent bikes for their lucky offspring, and as I have done it with the 20" bike I thought I should do it with the 24" bike.

So lots of looking on google and I find the frame and bike I am looking for and I am surprised that it's a Carrera Sol (the girls equivalent of the Carrera detonate). It has cable discs, a proper 4 point linkage rear suspension, Sram X3, which is all a good start but has an awful spring rear shock, spring front shock (an RST capa which is the best of the spring shocks though), and grip shifts (I cannot see why manufacturers insist on putting on gripshifts to kids bikes, they are just too difficult for them to use and underbar shifters are so light and easy now).

So a few months of searching ebay and Gumtree and find an example that has been genuinely only used 3 times, and it's in the town where my parents live(bonus), the family want £100 but I put in a cheeky bid of £85 and they accept. So ring my Dad who dutifully goes and collects it and stores it until I next see them.

I will post piccies of the bike when Flickr starts working again (won't let me get the URL to share so you will have to be patient)

Yakboy

Right Flickr has started working again so here's the bike



My daughter is not really into pink but at least it's a dark pink.
So it's a whopping 14.5kg!!! but it should be easy to save a good few kilo's without breaking the bank.

So first task was to sort out the suspension as even with no preload and me (all 79kg of me) riding it the shock hardly budged. So a quick visit to my friends on Retrobike scored me an unused Manitou SR airshock for £45. So it was off with the coil shock.



A whopping 469g and on with the airshock...



A svelte 203g

The suspension bushings swapped over reasonably easily but there was absolutely no lubrication in the bushings!! I thing I will disassemble the other linkage points and grease them . Anyway it all looks like this.



And with a quick pump up with the shock pump it works well (I will need to download the instructions for the shock to get the precise pressures for my daughters weight and also get to grips with the dual air chamber system which is a bit different to the RP2 I am used to). The only problem is that to pump up the bottom chamber is that I need to take the shock off it's mounting as there is not enough room to attatch the shock pump connector as it's so close to the frame. Does anyone know if you can get 90 degree connectors to overcome this?

So next task is to systematically strip the bike and weigh the components and find out which one's are very overweight and can be changed at reasonable cost. I am no weight weenie but with kids every gram can help make the riding experience more pleasant.
Budget wise I am trying to keep the cost below £370, which is what it would have cost me for a branded kids hardtail.

Chunkers1980

can't you turn the shock around?

Angus Young

This is exactly where I find myself right now with my 9 year old just about outgrowing her Scott Spark 20 so I'll be very interested to see how you get on with this. Keep posting.

mattrixdesign2

Not bad bikes these little Carreras, only gripes are; the shifters are useless, quick swap to to X3 underbar types does the trick. The reach casette is a screw on, and our last one broke easily. The forks on my lads Blast don't funtion, he just doesn't have the weight to make use of it.

Other than that sturdy little bikes. I reckon if you are on a weight saving mission I would go single up front, and drop the mech/shifter etc.

There is a thread on here where someone had heavily upgraded a Blast (I think), and even changed the wheels and fork, great work.

My youngest needs a new bike for Xmas as the Blast is now well used and a touch heavy, going to look for ridgid, may give Frog bikes a look, Isla are just too expensive.

Antm81

Angus Young wrote:

This is exactly where I find myself right now with my 9 year old just about outgrowing her Scott Spark 20 so I'll be very interested to see how you get on with this. Keep posting.

You're lucky, my 9 year old has all but out grown her 24" carrera Luna. She can comfortably ride my other half's scott contessa (and she's 5'6"). Trying to find the right replacement at the right price is hard, plus most coil forks will be terrible for her so need an air fork so I can set it better to her weight.

Yakboy

Chunkers1980 wrote:

can't you turn the shock around?

I don't know if the top valve will foul the linkage but will certainly have a look when I next get the bike out of it's hiding place (It will be a Christmas present)

Yakboy

mattrixdesign2 wrote:

the shifters are useless, quick swap to to X3 underbar types does the trick
Other than that sturdy little bikes. I reckon if you are on a weight saving mission I would go single up front, and drop the mech/shifter etc.

I already have a pair of x3 shifters that I got in CRC's sale for £15 and was going to go for double upfront as a 22T will be really useful for some of the steep stuff at Dalby. The crank set is riveted steel rings though (I could drill off the 42T ring and fashion a bashguard). The cranks are 155mm which I feel may be a tad too long and was considering a 140mm crank (using a redrilled old shimano alloy crank)





A couple of picks of the crankset

Littlebigmatt

Don't know if you found a solution but Topeak do a 90 degree adapter
http://www.topeak.com/products/Pumps/Pressure-Rite

Yakboy

Littlebigmatt wrote:

Don't know if you found a solution but Topeak do a 90 degree adapter
http://www.topeak.com/products/Pumps/Pressure-Rite

Superb, Thank You, that's just what I'm looking for

dirkpitt74

Will watch this with interest as my lad will probably need a new bike in the next 12 months.

The Rookie

Air pressure required is dependant on the leverage ratio of the rear suspension so very much doubt you'll get any recommended pressures!

Those 'mini Banshee's do look like a reasonable FS for kids unlike most the trash out there.

Yakboy

Bit of an update.

I have found a set of 140mm cranks which have been professionally shortened and as they are old shimano stock I have got a 24T and 34T chainring from retrobike. I think I might sandblast them and spray them as the silver doesn't go with the rest of the colour scheme..what do you think? They are lighter which is a bonus too.



Next I've replaced the huge saddle with a Madison Y04 which is much more anatomic and 100g lighter



Then last for the moment (and the most costly at £57 the pair ) is the tyres. The old no name tyres had very hard rubber and were 880g each so the rocket rons with a much softer compound and 430g each save a huge amount of rolling weight and should be more grippy. I could go tubeless (it has been done before on non tubless rims but I will probably stick with tubes)



So the next task is the front fork..I have this waiting in the wings

Yakboy

Had a spare hour and a half this Sunday and my daughter was at a friends house so I thought I'd work on the cranks.

So I sandblasted, primed , baked (I have an understanding wife who does not mind if the oven becomes a paint booth!!, then a coat of black plastidip (luckily I have all this stuff knocking about in the garage so no financial outlay). Then a 30 min bake at 40 degrees and couldn't resist putting them back together with some of the bling that is going on the bike.

The black is definitely better than the silver and hopefully the plastidip will be fairly scuff proof.



A definite improvement on the previous cranks and half the weight.

With regards to the front derailleur I assume I just lower it on the seat tube as I now only have 2 rings up front?

The Rookie

Good effort, look very like the Exage cranks I have on my retro....

poah

I'm on the look out for a 24 inch detonate for my lewis. he currently has a 22lb carrera blast that I can transfer all the stuff over.

nice choice mods on the bike. getting tubeless and lighter tyres make a huge difference to the ability to ride up hills for the kids.

Yakboy

Another update:

Took off the RST Capa fork and did a trial fit of the Fox Float 80 RSL fork (picked it up for £45 from one of the nice folks on retrobike). In pretty good nick, a bit of paint scuffing but the stanchions are good and it has apparently been serviced in the not to distant past but could do with an oil change.

Anyway heavy spring forks



Lighter New Forks



And a look at the forks in place



The geometry is a bit more laid back but not too bad. Measuring the reach on her old 20" and it's 50cm. On the 24" it's 62cm so I will change the stem from the current 90mm one to a 38mm one which should improve things. I won't cut the fork down as I think it will look OK with spacers at the top.

With regard to the fork I tried it with 30psi and it is so much more responsive than the spring CAPA. When I change the fork oil should I co for a lighter oil (say a 5wt ) rather than the 10wt recommended so the fork is even more responsive for the lower weight?

Yakboy

POAH wrote:

getting tubeless and lighter tyres make a huge difference to the ability to ride up hills for the kids.

How did you go tubless? Did you just get some rim tape, valves and sealant?

Antm81

Gorilla tape, valves and sealant works really well. It's what I used on POAH's recommendation and will be looking at for my daughters new bike.

Angus Young

What does it weigh now?

Barrelmaker

Good work with the bike. Going tubeless will be easy, I have a done a couple of sets of wheels using gorilla tape, old valves from chopped up tubes and home made sealant, so far so good, just tweaking the sealant mix. The only issue I had was getting some of the tyres to seat, but with some perseverance they eventually seated and inflated.

Yakboy

Angus Young wrote:

What does it weigh now?

Doing the maths on the weight savings I've already made it should be 2 1/2 kilo's lighter so that should make it 12kg at the moment. If I go tubeless that may save a few hundred grams but there are not many more weight savings that can be made. If my daughter decides she wants hydraulic discs that would save a chunk but that will be for future days

Yakboy

A quick update..the 38mm stem arrived today so it was off with the old 90mm stem



and on with the new one



I don't know why the Chinese feel they have to try and make out it's a Truvativ stem :roll:

The reach is now 54cm so a bit less stretched out

Just got some 7wt fork oil delivered so next job is a lower leg fork oil change

Cqc

I'm feeling very Jealous of your daughter ; when I was her age I didn't get such a nice bike! Great mods on this bike mate, really big improvement!

dirkpitt74

Looks good. Some good weight saving going on.

Are the Fox forks for a 26" wheel?

Yakboy

DirkPitt74 wrote:

Looks good. Some good weight saving going on.

Are the Fox forks for a 26" wheel?

The forks are Fox Float 80RL forks for 26" wheels. This means it lays the bike back a bit but looking at the side profile pics not too much...and I got it for £45 and apart from needing a lower leg oil change it's in pretty good nic.

dirkpitt74

Thanks for the info.
Great build - keep it up!

poah

the A2C of the standard fork is about 400mm

Yakboy

POAH wrote:

the A2C of the standard fork is about 400mm

Sorry to be a bit thick but what's A2C?

apreading

My guess: Axle to Crown?

Yakboy

apreading wrote:

My guess: Axle to Crown?

Ah makes sense..wellI guess I'll get out the tape measure tommorrow morning