# Lightening my son 20" mountain bike



## MikeRock98 (Apr 17, 2013)

I know some parents here probably have done this with the weight of these stock 20" mountain bikes.

My 7 year son has a Cannondale 20" mountain bike stock but this summer i have some plans on making the bike lighter so he will have more fun on the trails...

He's 4'6" and 66 lbs 

Heres the idea so far: Id like any input or suggestions so i dont waste money on parts that i dont need..

1. Replace heavy 20" shock with a Answer Carbon Fiber Ridged Fork made for a BMX bike.....Id imagine this would make a significant weight difference and i really dont think my kid need a shock at this point in his riding experience. He is doing beginner/indeterminate XC trails only.

2. Replace the stock wheel set with a custom build with some Profile Racing 6 speed hubs. The current set up is for 6 speed and id like for him to get use to gears so instead of single speed....Id figure id lace up a set of wheels using as light of wheels i could find mated to a set of profile racing 6 speed hubs.

3. Carbon fiber stem, handlebars, seatpost, and seat clamp. And Titanium bolts for about every bolt on the bike


What do you think.....I think he is well within range on going all carbon fiber supplement parts throughout the bike...

What have other parents done to lighten up there kids bikes and do you guys see any problems with a carbon fiber ridged fork on a kids bike....i figure he is light enough not to crack a fork like that...

thanks and see you all on the trails.


----------



## A Pile Of Tile (Apr 27, 2013)

You asked for an opinion, so I will give you one. But it is only that....an opinion.

Sounds like a bad idea to me.

Answer Carbon forks are expensive ($150 Eriks bike shop .com). Carbon stems, handlebars & seatpost's are expensive ($300 for the set is the cheapest I've seen). Titanium bolts are expensive. (Around $4-$8 a bolt). That alone is around $500, and for that you can find a pretty sweet deal. I would take all that money and buy a craigslist bike thats lighter and better than the one he's got.
My 11 year old son is riding a 15" Schwinn with 26" wheels that we picked up for $100. I bought some Manitou forks for $40, threw on a new Seat, seat post, stem and bars for about another $100....so for $240 I got him one of the coolest (Really light...25lbs) Schwinn's I have ever seen.

What we got for $100....









What we upgraded too....


----------



## Hairllama (Oct 27, 2006)

First of all, that fork won't have mounts for brakes - BMX forks don't have provisions for them. Kids are tough on stuff, they smack into things, scratch things, etc. Carbon for a kid is not something I would do. Swap out the heavy suspension fork for a much lighter, yet tough trials fork and let him ride the wheels off the thing. That's just my opinion . . .


----------



## GTscoob (Apr 27, 2009)

Sounds like a lot of money to pour into a bike he'll outgrow soon enough. Cockpit components can move to the new bike and you could relace the hubs to 24 or 26" rims when he grows. 

If you spend this much money on his bike, will you still let him ride it around the neighborhood or to friends houses? To school?

Get some BMX racing tires, they'll be cheap and a ton lighter than whatever is on there. Replace any steel cockpit bits with alloy parts. Maybe relace lighter rims to the stock hubs if you're really concerned about rotating weight.


----------



## moronm (Mar 23, 2011)

GTscoob said:


> If you spend this much money on his bike, will you still let him ride it around the neighborhood or to friends houses? To school?


agreed, kids are hard on bikes, no matter how careful they are, especially with a group of friends, get dropped abused etc, if you are going to be too afraid to let him ride the hell out it, then why bother?


----------



## MikeRock98 (Apr 17, 2013)

I wasnt too concerned with the price of the components.....

The fork i can barter some work out for, and the hubs i can probably get for free or next to nothing.....LOL....dont ask!

The real $$$ would come from the carbon fiber components and the titanium hardware which is a last ditch effort...

Id think i could get the components for around $300 then there is the wheels and probably ti spokes....Yeah and hopefully would be able to move the parts to a new bike when needed

If i spend $1k in this bike it would still be cheaper than about the price of the fork on my bike....Which to make him be able to have more fun....its a minor cost....

The scratches and roughness comes along with biking and is the least of my concern i just dont know how well ridged carbon forks hold up on a mountain bike which were not made for that kinda terrain... I would like to look it to these trails forks hairlama was mentioning....

And of course id let him ride around the neighborhood with the bike.....thats whats its for as well....its not a trophy bike or show bike......things get ridden and break....it happens in this sport.....LOL


other than that any other concerns?


----------



## TwoTone (Jul 5, 2011)

Quickest and easiest place to lose weight- the tires. Get some Moe Joes

Mow Joe HS 371 | Schwalbe North America

It's your money, but I agree with others on spending that much on a 20 inch bike and I dropped a ton of money into my son's 24 inch bike, but that is because it will last a lot longer than a 20 does.


----------



## GTscoob (Apr 27, 2009)

Sounds like you already had your mind made up. But really, how upset will you get at your kid if he loses this bike after you've dropped a grand into it?


----------



## GrayJay (May 16, 2011)

The stock singlewall Alex rims are reasonably lightweight, I recently weighed a 24" version of this same rim at 400gr, the 20" should be around 320gr . Ridiculous part of the wheelset is that they used 36 spokes, get light road hubs and re-lace the stock rim with 18 spokes rear (12 drive side, 6 NDS) and either 12 or 18 spokes for front, will be plenty strong for a kid. Tires, fork, crank will be the other big areas of weight savings for that bike. Take the entire bike apart and weigh the parts, figure out if they snuck in some grossly overweight parts. Novara 20" bike I recently started fixing up had 450gr steel handlebars! I agree that carbon components and Ti bolts are probably the very last area to try to save weight only after you have taken care of upgrading the big heavy parts first.


----------



## chuckactor (Apr 11, 2013)

If you are looking for a lightweight fork check this out:

Bloodline 20" Black Fork Disc Brake Tab BMX Trials | eBay

It's a trials fork so it might be a bit longer than the stock suspension fork. it is aluminum and has a disk brake mounting tab. I've been tempted to buy one for my kids older Hotrock 20. Can't beat the price.

Your best bet for light wheels are BMX ones. Checkout this article...

FAQLoad - Adding gears to a single speed BMX

I went the Ti/Carbon route on my boys BMX bike. It gets expensive but I got my son's mini down to 11.5lbs and my older boys jr to about 12.6lbs.

Chuck


----------



## MikeRock98 (Apr 17, 2013)

GTscoob said:


> Sounds like you already had your mind made up. But really, how upset will you get at your kid if he loses this bike after you've dropped a grand into it?


i don't expect it to happen but if it does. It wouldn't be the end of the world. My nephew just lost the iPad I bought him for Christmas last year. I just won't buy him a new one for a while.



GrayJay said:


> The stock singlewall Alex rims are reasonably lightweight, I recently weighed a 24" version of this same rim at 400gr, the 20" should be around 320gr . Ridiculous part of the wheelset is that they used 36 spokes, get light road hubs and re-lace the stock rim with 18 spokes rear (12 drive side, 6 NDS) and either 12 or 18 spokes for front, will be plenty strong for a kid. Tires, fork, crank will be the other big areas of weight savings for that bike. Take the entire bike apart and weigh the parts, figure out if they snuck in some grossly overweight parts. Novara 20" bike I recently started fixing up had 450gr steel handlebars! I agree that carbon components and Ti bolts are probably the very last area to try to save weight only after you have taken care of upgrading the big heavy parts first.


i think this has steel bars too. I figured I could get the hubs for free but I need wheel suggestions and ill try to get some sun ringle or velocity wheels or something for cheap and probably use the profile hubs still. His bike is like twice the weight as mine and I'm 190 lb and he is 66lbs.



chuckactor said:


> If you are looking for a lightweight fork check this out:
> 
> Bloodline 20" Black Fork Disc Brake Tab BMX Trials | eBay
> 
> ...


i think this is what I'm gonna get and save the bartering for the rims or the spokes. I know how expensive this could get. My mother always did it for me and I've alwayed planned on doing the same for my son. If you want to be competitive u need the right equipment.


----------



## BXCc (May 31, 2012)

I have been looking at this eBay seller for a while now. They have a bunch of carbon bars, stems and seat posts. They are all branded bontrager, FSA or 3T. I would be nervous about running them on my bike but for a kid under 100 pounds, they should be more than strong enough. You could get all 3 items shipped for around $100 or so. 
items in Bicycle parts store on eBay!

Carbonal is another options for post, bars, and stem. 
Carbonal Technology


----------



## MikeRock98 (Apr 17, 2013)

And this is the kind of carbon stuff i was thinking about.....i wasnt gonna go all eastern carbon bars and stuff and just throw my money out the window on $200 bars, 150 stem and 150 seatpost...Personally id buy him a thompson seatpost and stem because they are pretty light and the quality is top notch....I once bought a carbon fiber seatpost on ebay and cracked it in half in 3 days, but i was around 200lbs at the time.....I know there are plenty of deals to be had on ebay....And he will be gone for most of the summer so i have time to hunt down parts....

Thanks for that seller though....I might just pull the trigger on all three from that guy cause they seem cheap and and i figure for someone as light and hes not jumping off rocks and ledges......hes just going up hills and downhills with very little drop offs and jumps....


----------



## jplonks (Apr 15, 2013)

Another place to look at for some weight saving are the bottom bracket and the cranks.

Most bottom brackets in kids bikes weigh a ton und don't function that well. Get him a light, good bottom bracket, doesn't have to be titanium (but rest assured, there are others who put a titanium bottom bracket in their daughter's 20" bike...) - can you access these pics here ? - Islabike Beinn 20 Innenlager Tuning - Fotoalbum auf MTB-News.de - that's 180 grams off, just with the bottom bracket...

Cranks: Most stock cranks on kids bikes are way too long. Additionally, imho, hardly anybody really needs 3 chainrings in the front, especially not kids, but somehow most kids bikes come equipped with 3 chainrings - probably for the looks. So I'd go for single chainring front crank. My daughter (5, currently on 20" wheels) uses an old shortened XT crank (like these: Shimano Kurbel XT FC-M730 (tuned) 150mm, 4-kant - Gewicht von Teilen auf der Waage - MTB-News.de , but shortened down to 10,5 cm [if I remember correctly] or try this guy here: BikeSmith Design and Fabrication ), a single chainring in the front and 7 gears in the back. Works really well - MTB-News.de - IBC .

And you should not be bothered too much by other people calling you crazy for pouring a lot of money into the bikes of your kids - if you spend 1000 bucks on a fork for your bike, why should you go for "as cheap as possible" in your kid's bike, given that your child could use a light bike much more than you.


----------



## mtnbkaz (Feb 2, 2004)

Your kid is 4'6"? I'd be saving money for a 24" bike build at that size. 

I added an old Easton carbon bar & Thomson post to my kid's Hotrock 20 but mostly because I had the old parts sitting in the junk box in the garage. I weighed the stock stem and it wasn't that heavy so I kept it. (Hard to find a short stem with the rise that the stock one has and a normal lower-rise model wouldn't fit as well.) I'll upgrade the crank & BB as parts break or wear out. I'm in the process of converting one of my old hardtails to disc brakes so the Hotrock will probably get some hand-me-down Avid Ultimate v-brakes to replace the cheap stockers.

I would not put a carbon fork on my kid's bike. It tends to get tossed around in the dirt/rocks at the playground. Even the ends of the carbon bar were getting shredded until I added ODI grips with the plastic endcap & lock ring that protects the end of the bar better than a rubber grip did. I don't think a carbon fork would have a long or happy life on my kid's bike.

Personally, I doubt you'll get much bang for your buck with Ti bolts. But if it's just a fun project and you have the money to burn, then have fun.


----------



## tubored (Mar 13, 2012)

Has anyone found any rigid fork options (with reasonable A-C dimensions) for 20" mountain bikes that have bosses for v-brakes?


----------



## MikeRock98 (Apr 17, 2013)

jplonks said:


> Another place to look at for some weight saving are the bottom bracket and the cranks.
> 
> Most bottom brackets in kids bikes weigh a ton und don't function that well. Get him a light, good bottom bracket, doesn't have to be titanium (but rest assured, there are others who put a titanium bottom bracket in their daughter's 20" bike...) - can you access these pics here ? - Islabike Beinn 20 Innenlager Tuning - Fotoalbum auf MTB-News.de - that's 180 grams off, just with the bottom bracket...
> 
> ...


I didnt even think of the BB......Man thats a good idea....the cranks are 140mm and its a hard size to find.....Ive only found the set of shimano's the bike has and a set of sram 140mm kids cranks...

The one thats on the bike is currently 1x6 with a bash guard/chain guide....

I will be taking out his bb tonight and weighing it.....Id imagine i could save weight easily here if it has a steel spindle



mtnbkaz said:


> Your kid is 4'6"? I'd be saving money for a 24" bike build at that size.
> 
> I added an old Easton carbon bar & Thomson post to my kid's Hotrock 20 but mostly because I had the old parts sitting in the junk box in the garage. I weighed the stock stem and it wasn't that heavy so I kept it. (Hard to find a short stem with the rise that the stock one has and a normal lower-rise model wouldn't fit as well.) I'll upgrade the crank & BB as parts break or wear out. I'm in the process of converting one of my old hardtails to disc brakes so the Hotrock will probably get some hand-me-down Avid Ultimate v-brakes to replace the cheap stockers.
> 
> ...


The ti bolts was just an after thought but your probably right a 24" is probably in the future.....maybe like a year away but i want him to get the most out of riding now while he is SUPER interested in mountain biking...

We've tried all the team sports from, Football, Baseball, Basketball, Soccer....even swim team, tennis and golf lessons, and Now Mixed Martial Arts, and Gymnastics.....The sport he leans most to is MMA cause he does it for his after care program, gymanstics cause he loves to flip! LOL and DAILY MOUNTAin Biking....

His school is connected to a state park which has a mountain bike trail 8 or so miles of XC single track....He wants to ride every day! He doesnt want to play any other sports right now than mountain biking so all the money this year i wouldve spend on team sports and equipment has been practically saved cause a yearly membership to the park systems here is $25.



tubored said:


> Has anyone found any rigid fork options (with reasonable A-C dimensions) for 20" mountain bikes that have bosses for v-brakes?


I think the trail fork in this thread would work.....it would be much lower considering my sons mountain bike has a 14 inch axle to steerer crown on the suspension fork, and the trail fork is 11.5 inches....just to keep in mind...

I heard there is a company in california making custom fox forks for 20"s but they are extremely expensive.....

Im still searching and will post up all the results of this build


----------



## GrayJay (May 16, 2011)

For about the same weight at the carbon trials fork you are looking at, it is fairly straitforward to modify an early manitou 26" fork down to either 20" or 24" wheel size.
Great writeup on the procedure by one of our forum members is at;
FAQLoad - 20" front fork build

I recently took inspiration from this tutorial and built my daughter a 20" manitou. I was initially a bit intimidated by the tutorials heavy use of lathe, mill machine tools to accomplish the needed modification, but I did the same conversion using little other than a hacksaw and hand file, it came out great. Probably hardest part is just getting the pressed-on cast fork end (dropouts) off of the lower tubes. Without access to machine tools, I just cut the lower tubes about 2cm above the dropout then used a hacksaw blade to make a couple of verticle slits in the remaining stub of tubing pressed into the dropout. THe slits help to weaken and de-tension the tight press fit between the tube and the dropout. Next I drilled a couple of holes in the tubing, just above the dropout so that I could pass a large nail through the tubing and (loosely) hang the assembly on the through-nail between jaws of a vice and then hammar the dropout down and off of the tubing stub. 
THere a a lot of variations of how the early manitou 1,2,3,4 forks were constructed. Early and later lower end manitous put the elastomer below the stanchion, some later forks moved the elastomers up to the top, inside the stanchion. For a short fork conversion, stay away from any of those that used externally butted steel stanchion tubes, the butted section of the stanchion is too loose when re-located up near the forks upper seal/bushing. The very earliest Manitou 1 fork used non-butted steel and some later models utilized unbutted aluminum stanchions that make a 20" conversion much easier. 
For any kids manitou conversion, just run a spring on one side of the fork, no need for 2 springs or urethane kabobs with a small kid. You can either stick with elastomers which also provide reasonable dampening but I opted to convert to a coil spring and stretched it to around 60mm travel. There is enough inherent friction in the operation of the fork that it dampens OK with the light spring pressure. 
Overall, huge improvement on the too-stiff 5+ lbd junker RST fork that the bike started with and the vintage CNC fork components also have high bling factor!


----------



## BXCc (May 31, 2012)

Better grab this one quick. It probably won't last long.

Easton EC70 XC Riser Bar 2012 | Easton | Brand | www.PricePoint.com


----------



## MikeRock98 (Apr 17, 2013)

GrayJay said:


> For about the same weight at the carbon trials fork you are looking at, it is fairly straitforward to modify an early manitou 26" fork down to either 20" or 24" wheel size.
> Great writeup on the procedure by one of our forum members is at;
> FAQLoad - 20" front fork build
> 
> ...


This might be the option as well.....the laave thing had me a bit turned off till you explained what you did.....i might be able to find one of these in the back of my friends bike shop just laying around....there are tons of old bike with early series answer shocks....

THanks



BXCc said:


> Better grab this one quick. It probably won't last long.
> 
> Easton EC70 XC Riser Bar 2012 | Easton | Brand | www.PricePoint.com


Yeah that deal is hard to beat.....might have to buy a few more things to make shipping better....

Just picked up a set a avid speed dial 7 levers for him and hes gonna use the rest of my jagwire ripcord and re-do his brakes this weekend...


----------



## GrayJay (May 16, 2011)

For appropriatly short BMX cranks, check out e-bay vendor BMXguru for Sinz and odyssey cranks. Note that the ISIS spline cranks are about 1/2 the price of square taper if you are changing the bottom bracket anyway. 
Odyssey Black Widow Euro Crank Arms 150mm Black NEW items in BMXGuru store on eBay!


----------



## Welnic (Feb 6, 2013)

BXCc said:


> Better grab this one quick. It probably won't last long.
> 
> Easton EC70 XC Riser Bar 2012 | Easton | Brand | www.PricePoint.com


I put the 25.4 bars on my kid's 20" Scott Scale. The stock stem and seatpost seemed to be reasonable, but the stock steel handle bars were very heavy. Other than that I replaced the tires with Small Block 8s and put in lighter tubes. Rims would probably be the next thing I would replace.

Replacing the fork with a rigid one would be a good upgrade, but I don't think my son would see it that way.


----------



## rti27 (Dec 9, 2012)

Your kid will be 5' at the age on 9, then he can get on a 15" frame 26er. As for me i would let him work on handling the heavy 24" for two years.
plenty of fundamentals for work on between now and then.


----------



## MikeRock98 (Apr 17, 2013)

Yeah, it would be cheaper for me to just wait, but with this summer heat down here in S. FL, id like to get my son everything need to make the ride easier.....If thats me spending a few $$$ on his bike to do so.....Its only $$$ and i work to provide for my son, and nothing more.....Its just us two full time so he is my only focus and i work my tail off so he can have everything i didnt as a kid....

So far, i bought a 

carbon fiber seat post ($60).... original was steal and over 350 grams....
Seat, carbon fiber and titanium bontrager seat ($35), 
handlebars easton x70 from the thread that were on sale for ($35)
avid speed dial 7 levers ($20)
Jagwire Ripcord brake cable set (Free) - Had two piece left over

Based on the first $150 spent.....my weight calculation have us saving over 2lbs just from those parts..... 1.2 lbs just from changing the seat and seat post....


----------



## BXCc (May 31, 2012)

Nice! Any idea on the original weight? My 6 yo daughter is on a GT Laguna 20. It weighs 23 pounds even and is stock. Bars are probably the only thing I will do. Every body has their own things to spend money on. Do kids need expensive bikes? Definitely not. Do I? Nope. But it sure is fun sharing a hobby while they still think we are cool. I just choose to spend my money on bikes and skis rather than $110 american girl dolls. Now there is a pointless purchase. 


MikeRock98 said:


> Yeah, it would be cheaper for me to just wait, but with this summer heat down here in S. FL, id like to get my son everything need to make the ride easier.....If thats me spending a few $$$ on his bike to do so.....Its only $$$ and i work to provide for my son, and nothing more.....Its just us two full time so he is my only focus and i work my tail off so he can have everything i didnt as a kid....
> 
> So far, i bought a
> 
> ...


----------



## GrayJay (May 16, 2011)

I would guess that the 20" cannondale 6-speed is aroung 25 lbs. It does at least have alloy stem, bars, seatpost and crank-arms but heavier parts it comes with are 36 spoke wheels, pressed-on steel chaingring and a suntour suspension fork. 

Too funny on the $110 american girl doll comment, my 7-yr daughter is saving her lemonaide stand money to buy one, I cannot yet seem to convince her the $ would be better spent on carbon and Ti bike parts.


----------



## Billinsd (May 10, 2012)

BXCc said:


> Better grab this one quick. It probably won't last long.
> 
> Easton EC70 XC Riser Bar 2012 | Easton | Brand | www.PricePoint.com


now it is 15% off?


----------



## stom_m3 (Jun 28, 2011)

MikeRock98 said:


> I know some parents here probably have done this with the weight of these stock 20" mountain bikes.
> 
> My 7 year son has a Cannondale 20" mountain bike stock but this summer i have some plans on making the bike lighter so he will have more fun on the trails...
> 
> ...


At 4'6" I would look at buying a 24" and pass on the 20". I'm all for tricking out bikes. You can read my son's build thread where I put my old XTR stuff on a hidden canyon. I also weighed the various parts if interested in knowing weights for the 20" bits. But if my son was as tall as yours, I would buy the Scott Scale JR RC which comes pretty trick at $1200ish. Switch the drive train to a 1x10, buy shorter cranks and whatever carbon bits you want. My .02.


----------



## MikeRock98 (Apr 17, 2013)

yeah ill probably be looking into a 24" for Christmas but this is just for the summer....

We've looked and sized my son on a scale jr but it is still way too big for him.....We even had a scott demo day last month at our local trail and he's still way small for a 24" 

A lot of what im buying will be able to be transferred to a new bike and if not there is always ebay! 

I appreciate all the comments and so far Ive really not pulled the trigger other than handlebars, brakes, seat, and seat post.....

We are going on vacation 2 of the next 3 weeks so this is kinda on the back burner till the second week of june....

But im not going stupid crazy on this bike or the next.....He's no professional, hes not a racer....yet! Im just trying to get him on the right equipment for the job....Like my parents did for me.....When I started BMX racing at age 8....I started with a stock mcs bike.....within 3 months I was winning races and my parents realized I was uber into bmx, and they made my bike as competitive as possible within financial reason...

Same with my kid.....hes played all sports and this is what he gravitates to the most....why not let him experience the joy of riding the trails with smooth parts like we have on our bike......If I had the components on his bike.....I probably wouldn't like my ride as much as I do on a sorta tricked out bike....

I just want him to enjoy himself as much as possible....if a few hundred $$ does that....its all good!


----------



## stom_m3 (Jun 28, 2011)

MikeRock98 said:


> Same with my kid.....hes played all sports and this is what he gravitates to the most....why not let him experience the joy of riding the trails with smooth parts like we have on our bike......If I had the components on his bike.....I probably wouldn't like my ride as much as I do on a sorta tricked out bike....
> 
> I just want him to enjoy himself as much as possible....if a few hundred $$ does that....its all good!


Completely agree. Right now everything out there is a tank and lugging a tank around a trail is no fun. My son is 4' 1" @ 62 lbs. I was able to get his bike down to 20lbs. His bike is still way to heavy in my opinion especially when I'm riding my 23.5lbs full suspension bike. He still does great on it. Good luck.

http://forums.mtbr.com/families-rid...in-hidden-canyon-20-going-put-xtr-726045.html


----------

