# Why are kids bikes so heavy?



## paulys_tx (Jul 14, 2007)

My kids have been racing BMX for about 2 years and now I am looking for a 20" mountian bike for my soon to be 6 year old. He had been riding his mini BMX bike on the trails for the last year, but could use some gears and bigger tires. Everything I have looked at is a tank. His BMX bike weighs 9 pounds and takes everything he has been thowing at it. I am thinking of having a custom frame built. How come no one has taken the best of the BMX world and merged it into a good light 1x9 kids bike??? The bikes I have looked at all have very heavy components. A 20 inch MTB doesn't need 36 spoke wheels or other crazy heavy pieces. I am looking for a light suspension fork to use - thinking about cutting down my old manitou 3 like I have seen here in the past. Any help with a light frame or fork would be appreciated. I know I am not the only one who has been through this. I think if chosen carefully, some one should be able to build a great 1x9 bike with suspension that weighs about 15-16lbs.


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## Cary (Dec 29, 2003)

It is going to be hard to hit 15 pounds, but under 20 is doable. Scott made a light hardtail, but the market for a $1000 kids bike is limited.


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## wycough (Mar 9, 2008)

We were in the same situation. My son has raced bmx since he was almost 5yo. He has been racing a full Ti Redline...very light. I had him another Redline with appropiate gearing and tubeless setup for the local trailsracing. He is 6yo 47" and 50lbs. I just finished him a his 26" build 1x9...check out the build and bike, but you may be a year off from something like this. http://forums.mtbr.com/showthread.php?p=7929828#post7929828


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## TigWorld (Feb 8, 2010)

I've built a lightweight 20" 1x5 with cut down manitou fork and it does make a huge difference to where and how a 6yr old can ride offroad, but there's lots of DIY to get it to work.



Unfortunately, no manufacturer will build a decent kids bike because there are only a handful of parents willing spend $500+ on a kids bike.


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## NYrr496 (Sep 10, 2008)

Tigworld, How'd you shorten up that fork? I have a couple of those layin' around.


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## TigWorld (Feb 8, 2010)

Check out my article here. Let me know if anything's not clear and i'll try to clarify.


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## m-dub (Apr 22, 2005)

"Why are kids bikes so heavy?" Cost, most people aren't willing to pay for a mini machine. I know people do for bmx but the parents can just sit and watch that 

I built one at just under 21 lbs for my son for under $600 ( see below) and he hammers on it harder that most kids twice his age. I have more than gotten my money out of it. I bought him a BMX to jump and thrash on but it just sits because he love the MTB so much. I could have easily built it 3 lbs lighter for $$$. But don't feel it would have changed his riding much at all. Its not like gate snaps matter when your not racing. If I knew how much he was going to dig it, I would have spent twice as much. A custom would be cool but there are some solid frame out that would save you a ton of $. If you want a legit fork, White Bros will make you one for $700

http://forums.mtbr.com/showthread.php?t=581791


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## NYrr496 (Sep 10, 2008)

TigWorld said:


> Check out my article here. Let me know if anything's not clear and i'll try to clarify.


Thanks. That's perfect. If I feel he's going to ride this bike two more seasons, I'll ge to it. No point in cutting up a fork if I'll be building him a 26er next year. Hmm.... Decisions....


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## paulys_tx (Jul 14, 2007)

Thanks guys for the input. I am going to try and build my own now! Checking on having some frames built for little guys. Like a mini bmx bike with 135 rear spacing and disc mounts. I will keep everyone posted if these become available!


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## khaotom (Mar 14, 2011)

Tell me if I am doing right, I am eyeing a 2006 Kona Makena Frame. Here's what I plan to do..
1. Lace the front/rear wheel with BMX rim and Shimano M590 F/R Hub
2. SRAM X4/X5 Derailler with SRAM X4/X5 8spd/9spd trigger
3. Sinz Crank Expert ISIS with 34T ChainWheel...what BB should I use?
4.Deore LX V-Brake Set.
5. Seat Post, Stem - Not decided yet
6. BMX Aluminium Fork or RST Capa?
What else do I need? Am I missing something, 1x9 or 1x8? I guess I would also have a find a medium rear derailluer cage?
This is for a 5 year old, 46 inches.


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## TigWorld (Feb 8, 2010)

Just make sure that frame has 135mm rear dropouts and you should be good to go.


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## NYrr496 (Sep 10, 2008)

My son's Fisher frame was probably 130mm. I was able to get the 135mm hub in but I felt it was stressing the frame. I had the wheel guy at the bikeshop open up the hub to service it and fool with the spacers on the axle so it would drop in. Ended up working perfectly.


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## Fattirewilly (Dec 10, 2001)

I've just rebuilt a 24" wheeled Hotrock I got for $25. The RST suspension fork on it is slightly over 4 pounds. I tried to find to a rigid fork (suspension corrected) without going custom and gave up. I have a 3.0 pound Judy SL w/Englund cartridges sitting on the shelf for a 26" wheel kids bike in a year or two.

I weighed the frame to, just a little under 4 pounds I think. Not terrible, but not great. Cranks and V'brakes were acceptable. I wasn't willing to build custom wheels on this.

Chain guide removal; added ti bar, carbon post, roadie tape grips, XTR der. from my old parts bin, = 26.5 pounds.

The 20" Hotrock with just an alum. bar and carbon post swap is 24 pounds.


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## ShadowHunter (Apr 6, 2011)

Instead of Sinz cranks you may consider AC mini cranks (135mm-175mm). I believe them to be a bit lighter than the Sinz single speed cranks though the bottom bracket may need to be a little longer. Also for the bottom bracket you can get a Sinz ti that is pretty light as well. As for rigid 24" forks you can look at the inexpensive RedLine R6 BMX race fork which weighs next to nothing, though I don't know how it would hold up on a MTB trail but surely it would do fine as most little ones aren't going to be abusing it to much.

AC Cranks
https://www.jrbicycles.com/storefront/index.php?act=viewProd&productId=2122

Sinz ti BB
https://www.jrbicycles.com/storefront/index.php?act=viewProd&productId=50

RL R6 forks
https://www.jrbicycles.com/storefront/index.php?act=viewProd&productId=1582


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## CornbredNE (Apr 18, 2011)

NYrr496 said:


> My son's Fisher frame was probably 130mm. I was able to get the 135mm hub in but I felt it was stressing the frame. I had the wheel guy at the bikeshop open up the hub to service it and fool with the spacers on the axle so it would drop in. Ended up working perfectly.


Couldn't you also use a road bike rear hub? If I remember correctly they are 130mm and could easily be laced up to a 20" rim with a 8 or 9 spd cassette.


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## NYrr496 (Sep 10, 2008)

CornbredNE said:


> Couldn't you also use a road bike rear hub? If I remember correctly they are 130mm and could easily be laced up to a 20" rim with a 8 or 9 spd cassette.


Sure, but I had the XT hub.


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## Scoobytao (Mar 19, 2011)

You can get 20" rims in 36 hole congfiguration (and 36 hole hubs seem always to be on sale) and lace them up as an 18 spoke crowsfoot pattern (this will also allow you to reduce the dish). Also if you can find a light rim in a 48 hole configuration (uncommon but they do exist for bmx rims) you can do a straight laced 16 spoke front wheel with the spoke holes perfectly aligned since you are skipping every two holes. You don't want to radial lace the rear drive wheel though or a wheel with hub/disk brakes.

Reducing rim size alone makes the rim stronger. Also if you look at the span between spoke holes on a 32 hole 29er it will be about the same distance as an 18 spoke 20" wheel. 

Fewer spokes, less weight, cheaper and easier to lace (except the crowsfoot can be a little tricky). I call that a win, win, win.

This is what I did for my kid's bike and the wheels are plenty strong, but I still avoid doing bunny hops on it (not because I weigh 200lbs but because I never learned how to do bunny hops. sniff sniff)

The bike I built up this way was a Makena too. I think they are about the lightest 20" frame with a derailleur hanger.

With all the customization you are proposeing the bike will be under 20lbs. I did it on the cheap with used and scrounged parts and it came in just under 21 lbs, but also under $150 thanks to Craigslist and a large bin of spare parts.

I am not sure what kind of brakes you will run, but keep in mind that little hands don't have the same strength and early on my little guy had a tough time slowing himself down- he scared me.

We have a kids Mt Bike club here and he was about 5th in his most recent race out of a group of 40 kids ranging in age from 8 to 13. and he was the youngest in the top ten.

I do get the option to brag if I can pass on useful info.. don't I?


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## Cinq (Jan 2, 2003)

TigWorld said:


> Check out my article here. Let me know if anything's not clear and i'll try to clarify.


Wow, great article! Too bad I don't have the equipment to do all this but it was really interesting to read.

Kind regards,

Clemens


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## traffic002 (Dec 16, 2008)

Great thread. My 8y/o is outgrowing his mini bmx bike. I've been able to buy some time with getting a handlebar that has higher rise and is wider. So now my focus is to get his next bike lined up. This time, I'd like it to be more trail worthy.

I still don't feel that he needs a suspsension fork. So hopefully that can keep the complexity and weight down a bit too. Man, I think I have to brush up on my wheel building skills...

Great job on giving the kiddo a fighting chance and riding the trails. I can't imagine riding a 90# bike on the trail. Which is what these 27# monsters are for the kids.

I expect it has a lot to do with parents not wanting to spend $500+ on a kids bike they'll outgrow in a year. Also, having suspension and gears like dad is more popular than setting up proper geometry and gearing (and weight.) for the little rider.


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## cmc4130 (Jan 30, 2008)

wycough said:


> We were in the same situation. My son has raced bmx since he was almost 5yo. He has been racing a full Ti Redline...very light. I had him another Redline with appropiate gearing and tubeless setup for the local trailsracing. He is 6yo 47" and 50lbs. I just finished him a his 26" build 1x9...check out the build and bike, but you may be a year off from something like this. https://forums.mtbr.com/showthread.php?p=7929828#post7929828


that's rad that you had him racing bmx, and rad that you built him an mtb too.... but just wondering why not 24"s instead of 26"s ?

there are dirt jumper frames at that are 24"wheel specific out there--which does make a difference because they have an even shorter back end and higher bottom bracket.

Blackmarket Contraband (24" specific):


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## morningmist (Mar 15, 2011)

That bike is insanely cool!!!!!!!


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## RealDeal (Jun 5, 2011)

i just got a 24" for my daughter and it weights about 35 pounds. Full suspension


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## TigWorld (Feb 8, 2010)

Raiding the spare parts supply and a little bit of work in the machine shop can get you down to sub 23lbs FS 24":


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## Billius (Jun 10, 2011)

*Recommended Stock 20" Geared MTB?*

Hello all!

I've just moved to San Diego (Encinitas/Carlsbad) from London, UK and am trying to get my boys cycling (2nd attempt).

My 6.5yr old has outgrown his IslaBike Cnoc 16" so I have given that to my 4.5yr old. BTW that leaves be with a IslaBike Cnoc 14 (search for cnoc 14 islabike) which I'm happy to sell cheap !

So.. because we live in a pretty hilly area I really think he needs a geared bike. I don't think he's big enough for 24" bike (nor experienced) so I'm after 20"

I absolutely want it to be nice and light - I may be able to do some simple swap outs if they're easy mods - but I want to start with the stock bike being light if possible.

My quick review of bikes came up with the following models:
Specialized Hotrock 20"
Marin Hidden Canyon 20"
Gary Fisher Precaliber 20"

I'm also aware of the Kona Shredder, Haro and Trek MT 60 but don't know if they should be contenders?

I really liked the look of the GF Precaliber - looked lightest and good fork - but I can't find anyone who has the 2011 in stock still 

My son tried the Hidden Canyon in REI (where I can get a discount) so that is going to be the default choice unless there is a better alternative.

Look forward to any advice please!

Thanks

Bill


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## cmc4130 (Jan 30, 2008)

Billius said:


> Hello all!
> 
> I've just moved to San Diego (Encinitas/Carlsbad) from London, UK and am trying to get my boys cycling (2nd attempt).
> 
> ...


I know it's a debate that'll probably never end . . . but I think an extremely light and nimble singlespeed (e.g. bmx micro mini or mini) is waaaaay better than a mini-tank with gears.

The Specialized Hot Rock 20" 6-speed is supposedly approx 25 pounds. http://www.thebicycleescape.com/bicycleweights.html

But you can drop 10 pounds by going with a Redline bmx mini.

It's just soooo wrong that companies are selling bikes to children that are over half their body weight, or more.

The Redline Proline Micro Mini is only 14 pounds !









https://www.jrbicycles.com/storefront/index.php?act=viewProd&productId=2946

*BMX mini or micro mini?*
http://forums.mtbr.com/showthread.php?t=475553

Mountain Bike vs BMX (for 6y/o)
http://forums.mtbr.com/showthread.php?p=5347612&page=3


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## IAmHolland (Jul 8, 2010)

If you want light with gears, the Giant Xtc Jr. 20 is the lightest I know of. It uses a rigid fork.


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## Billius (Jun 10, 2011)

Thanks for the replies guys.

I actually looked at the next IslaBike up the range (Beinn 20) and it is 7 speed with really nice child size components and 19.4 lbs . Only problem... I'm not in the wrong country to buy it!!

Giant looks good - and its in stock in my LBS - I'll see what the boy thinks

Cheers

Bill.


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## Billius (Jun 10, 2011)

We bought a bright shiny red Giant XTC Jr 20 this morning from LBS. My son was cycling around the park 5 hours later (not having cycled on 2 wheels since 5 mins 1.5 yrs ago). Extremely proud but knackered dad!

Of course he then clipped some rocks and impaled his tender bits with much screaming a little later but the $1 for big crashes followed by re-mount seemed to work....


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## firemanj92 (Mar 29, 2006)

Billius, I've sent you a pm regarding the CNOC


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## khaotom (Mar 14, 2011)

TIGWorld,
What brake are you using on the Redline fork? Most of the rigid BMX fork doesn't come with brake mount. I am considering one of those v-brake plate, is it worth the bother or should I just go with a rst or suntour 50mm?


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## khaotom (Mar 14, 2011)

Alright, here's what I have got so far:
Trek MT60 frame, a set of wheel with Eastern Nitrous Ring Rim and Deore Hub, SRAM 951 Chain, SRAM 970 1x9 Cassette, a Nitrous Aluminum Gold MTB handlebar.

I am going to replace the Suntour fork with a BMX fork and am eyeing a KHE Tanaka LT with U-brake mount. Question is:
1. What sort of Headset should I get? BMX or MTB? Integrated or Standard? 
2. Can I use a MTB stem on the fork to connect to the handlebar or do I need a BMX stem?

3. Next I am going to try to get the BB out, my LBS failed to do that. If that doesn't come out, do i have to use the crappy 1-pc welded crank or can I just slap on a 32T chainwheel with something like a Square Taper Sinz Expert Crank?

4. As for the derailleur, will a long cage X5 work? My LBS recommend a medium cage, but I had a hard time finding this. 
5, With this setup, I will be running v-brake on the rear and u-brake on the front. Is this weird? Will I be able to use same brake lever for both?

Appreciate if anyone can help me out.

Thanks
CJ


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## m-dub (Apr 22, 2005)

khaotom said:


> Alright, here's what I have got so far:
> Trek MT60 frame, a set of wheel with Eastern Nitrous Ring Rim and Deore Hub, SRAM 951 Chain, SRAM 970 1x9 Cassette, a Nitrous Aluminum Gold MTB handlebar.
> 
> I am going to replace the Suntour fork with a BMX fork and am eyeing a KHE Tanaka LT with U-brake mount. Question is:
> ...


Hope I have helped a little.


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## TigWorld (Feb 8, 2010)

khaotom said:


> TIGWorld,
> What brake are you using on the Redline fork? Most of the rigid BMX fork doesn't come with brake mount. I am considering one of those v-brake plate, is it worth the bother or should I just go with a rst or suntour 50mm?


The BMX fork that came with the redline had a centre mount brake (like a road bike brake) on the front.


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## khaotom (Mar 14, 2011)

I am a bit reluctant to use the old fork, which weighs like 4+ lbs and has very little travel and not to mention the rust on the thread. 
So the option is either:
1. Get a BMX fork with U-brake boss and run U-brake on the front and v-brake on the rear.
2. Get a BMX fork with no brake mount and run without brake and add on a v-brake plate (if I can find one) later if needed. 
3. Get another heavy child fork (but threadless) for about $30-$40, that way I can also upgrade the Headset to something more attractive....

Thanks


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## NYrr496 (Sep 10, 2008)

khaotom, I don't know if I can get in trouble for posting this here, but I have a 1 1/8" threadless "suspension" fork I took off my son's Gary Fisher Precaliber when it was new. It accepts Vee brakes. We can make a deal if you want.


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## TigWorld (Feb 8, 2010)

There are some other 20" options from the recumbent crowd - eg 20" fork with disc tabs or get some bolt on v-brake bosses like these for the DMR trailbrade.


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## stom_m3 (Jun 28, 2011)

paulys_tx said:


> My kids have been racing BMX for about 2 years and now I am looking for a 20" mountian bike for my soon to be 6 year old. He had been riding his mini BMX bike on the trails for the last year, but could use some gears and bigger tires. Everything I have looked at is a tank. His BMX bike weighs 9 pounds and takes everything he has been thowing at it. I am thinking of having a custom frame built. How come no one has taken the best of the BMX world and merged it into a good light 1x9 kids bike??? The bikes I have looked at all have very heavy components. A 20 inch MTB doesn't need 36 spoke wheels or other crazy heavy pieces. I am looking for a light suspension fork to use - thinking about cutting down my old manitou 3 like I have seen here in the past. Any help with a light frame or fork would be appreciated. I know I am not the only one who has been through this. I think if chosen carefully, some one should be able to build a great 1x9 bike with suspension that weighs about 15-16lbs.


Great thread! I'm in the same situation. Have a 6 yr old, racing for 2 yrs on an Intense mini and now looking to take him mtn biking. Started looking around at 20" MTN bike options and there's not much out there. I'm deciding between the Scott Scale Jr 20 or the Specialized 20" 6spd. I love the idea of a custom 1x9. Add a decent kid fork that doesn't weigh a ton and I would buy it in a heart beat. I've seen parents spend $1.5k on their kids BMX bikes. If a company like Intense would make a cool little grom Mtn bike, I'm sure they would sell to the parents that really want to ride with their kid.

That said anyone have opinions on the Scott Scale 20" or Specialized? I like the Scott because it actually looks like a minature mtn bike. Thanks,

Steven


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## IAmHolland (Jul 8, 2010)

I like the Scott over the Specialized due to it having a front derailleur, but the crank should be 32-22 instead of 42-34, for mountain biking. There are others that have the front derailleur as well. Weight-wise, it's about the same as the Hotrock, ~25lbs.

The reason why I favor a front derailleur is because my son needed the extra gearing to actually ride some real trails with long-ish climbs, instead of flat-ish, or slight rolls.


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## TwoTone (Jul 5, 2011)

IAmHolland said:


> I like the Scott over the Specialized due to it having a front derailleur, but the crank should be 32-22 instead of 42-34, for mountain biking. There are others that have the front derailleur as well. Weight-wise, it's about the same as the Hotrock, ~25lbs.
> 
> The reason why I favor a front derailleur is because my son needed the extra gearing to actually ride some real trails with long-ish climbs, instead of flat-ish, or slight rolls.


The thing I learned is that it depends on your kid. I bought a Marin because of the front derailleur, I like Specialized and would have stuck with them.

Anyway, waste of money because he doesn't have the hand/finger strength to up shift the front. By the time he does, he be on a different bike.

It would have been better to take the saving from buying the Specialized and bought a Mega Range 7 SP cassette and derailleur for the rear.

Anyway, just my 2cents, since I'm going through this right now.


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## IAmHolland (Jul 8, 2010)

TwoTone said:


> The thing I learned is that it depends on your kid. I bought a Marin because of the front derailleur, I like Specialized and would have stuck with them.
> 
> Anyone, waste of money because he doesn't have the hand/finger strength to up shift the front. By the time he does, he be on a different bike.
> 
> ...


Yes, true, and it depends where you ride, and what the kids want to do. For most kids, doing the kid friendly rides, are adequate, but my son really wanted to hit the mountains in my area and not the popular kiddie areas.

I have to shift from 1-2 on the front for my son, but since I ride with him and make segments, of up and downhill, it's all good. Shifting to the 22T is easy, and can be done themselves, but shifting up isn't. Most of the time he runs the 22T on the trails with the 8 speed in the rear, but I make sure to switch it to the 32T on the long downhills and rollers. He had a Mega Range 7 freewheel on his Hotrock, first thing I did (originally it was a 6, but I could fit the 7 on). It wasn't enough to go up 7%-15% grades without hike-a-bike. For the more standard kid trails, he keeps it on the 32T. He still has to hike on the much steeper grades, but it's considerably less than before.

He gets lots of kudos for even attempting these rides, from other mtn bikers for sure. He's the only kid I ever see out on the trails, and because of his determination and enjoyment, his next bike will be a fully custom XS 26" with 24" wheels and near top notch parts.

Anyway, for me to put the front derailleur on the bike, I had to buy an aftermarket front derailleur clamp and ziptie cables, as the Hotrock doesn't have the frame for it. It's easier to remove the parts than to add-on.

The benefit for my son was clearly visible after the change, so it's not a waste of money on my end, but it depends on the situation as you stated. Many times you won't know, up front, what your kids will want to do, as they are still growing into it.

I would have bought my son the Scott or Marin if I knew he was going to enjoy it this much, and save myself some hackery to get something that fits where he wants to ride. The cut cranks would still be needed, regardless.


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## swimman (Sep 29, 2010)

Nothing like a tough steel bike a kid cannot break!


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## TwoTone (Jul 5, 2011)

swimman said:


> Nothing like a tough steel bike a kid cannot break!


Kid can't break a nice light Aluminum frame either.


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## stom_m3 (Jun 28, 2011)

swimman said:


> Nothing like a tough steel bike a kid cannot break!


I think this is the thought process that gives manufacturers the excuse to build a [email protected] bike. My son has been racing an aluminum Intense frame mini for 2 years w/ 1" speed rims with no issues. No bent frame, no tweaked wheels. Various parts have scratches and scuffs from crashing but everything has held up well. Even the carbon fiber bars are doing well. Racing pushes the manufacturers to make better quality components that are lighter and stronger. That could be the reason for lack of support for kid mtn bikes. It would be interesting if they had lower age groups for mtn bike racing. This would push manufacturers to build a more serious kid mtn bike with size options.


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