# BMX as MTB?



## Metalhack (Aug 13, 2011)

I have been reading through many of the threads in here and it seems the common factor with kids MTB's are that they are heavy,lousy front susp fork and under spec'd fpr the $$.

Im looking for a solution for my 5 year old and my 7.5 year old.

For the 5 year old I am looking at a Redline MX Mini and making it a SS MTB.

I couldnt post the link but if you add the www to redlinebicycles.com/bikes/bmx-race/2011-mx-mini you will see the bike.

Its only about 15.5 #'s and spec'd well. I would have to add a front brake, wider tires and gear it better. This setup I am pretty confident would be best for him.

Its the 7.5 yo (47 inches) that I am wondering about. Should I go with a similar setup as I mention above? maybe a 24" ?or should I go with a complete 24" MTB from either Haro,Specialized,Trek...etc?


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## TwoTone (Jul 5, 2011)

Thing is, the gears helps. I live in a hilly neighborhood and my 6 year old daughter rode my son's 20 inch Marin today for fun, well once she used the gears, she looked at my son and said " you shouldn't have let me try it, I want to ride it all day"

So I read a lot about single speed light weight BMX bikes, but for the rides I want take my kids on, they need gears.


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## stom_m3 (Jun 28, 2011)

I tried the BMX thing with my 6 yr old and it was too tough. Granted the tires on his race bike were too thin but the other issues were lack of gears. I geared the bike way down and it worked well but still didn't have enough umph to get it up the hills. The light weight of the BMX bike was definitely a plus but there were too many other downsides for it to be sustainable. 

I thought about buying a BMX frame and welding cable guides, new rear dropouts and widen the rear stays from 112mm to 135mm but that seemed like a lot of work. I decided to go the same route as Quasi888 which was to buy a complete and rebuild. You can read both of our threads to see the differences in build. I just finished putting a lot of the parts on the scale and will update my thread with the weights. The biggest area to save weight is the wheels, cranks and bottom bracket. Of course once you get that far you might as well provide a better shift and brake system too. Slippery slope. Let me know if you have any questions.


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## IAmHolland (Jul 8, 2010)

gears, gears, gears, gears!

kids don't have the leg strength for single speed on a mountain trail. Flat stuff, sure. Short sprints, sure. Long climbs, no way, unless you really want to punish your kid with failure to even start.

If you want light without work, look at the Giant XTC Jr. 20. It has a rigid fork, and should come in somewhere around 22lbs. It also has the tires I put on my kid's bikes. The Kenda Small Block 8 in 20x1.95. The suspension forks do help a bit with small bumps and hand fatigue, but it's not really necessary. A few minor changes and you should be able to drop it down further, kickstand removal, handlebar change, stem change, seat change, seat post maybe, rear derailleur change, crank change for lower gears.

Some of the kid bikes have really lightweight cranks, the bottom brackets are the standard weight square tapers usually (300+g).


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## dief (Jul 25, 2010)

My 6 year old son races BMX and also MTB with us on singletrack trails. He has a redline mini when he races and a specialized hotrock when out on the trails. I agree that when out on the trails they need gears! We just did 14 miles of singletrack with him and if he was on his Redline he would've never made it. Plus by the time you change everything out you're going to spend just as much as you would if you just bought 2 bikes. Check craigslist. I bet you can find 2 used for the price of one new


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## Metalhack (Aug 13, 2011)

Great info guys....seems like its unanimous that gears are needed. Thanks a lot!

Nice build Stom m3!


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## TigWorld (Feb 8, 2010)

Gears are essential.

But you can add gears to your Redline BMX - assuming the new ones still use the type of hub that mine did.


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## Metalhack (Aug 13, 2011)

I have been shopping and can't believe the lack of quality(actually I can) of kids MTB's. I think what I'm gonna do is get a couple quality BMX bikes and make it a 1x7. Then add the front brakes,tires and the other necessities.


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## indianadave (Apr 27, 2010)

I can't imagine my 5 year olf riding the trails we ride with a singlespeed... She does great on her Hotrock 1x6 though! It might be a little heavy, but it's not holding her back right now... I'm going to swap a couple simple parts for lighter ones, but she'll outgrow it too fast to warrant puttin a lot of money into it.


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## stom_m3 (Jun 28, 2011)

Metalhack said:


> I have been shopping and can't believe the lack of quality(actually I can) of kids MTB's. I think what I'm gonna do is get a couple quality BMX bikes and make it a 1x7. Then add the front brakes,tires and the other necessities.


Have you figured how you are going to get the rear hub to fit? Also do you know how to weld or have a welder? Have you found a place to buy cable guides, rear dropouts and v-brake bosses? I'm sure you can get them from a custom frame build shop. If you have a TIG or MIG welder, it would be relatively easy.

If you are going to go the BMX route, I've found that Redline actually sells Flight frames relatively cheap compared to every other manufacturer. Also, the Flight frame is one of the lighter frames out there. Good luck, post pics when you are done.


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## TwoTone (Jul 5, 2011)

Metalhack said:


> I have been shopping and can't believe the lack of quality(actually I can) of kids MTB's. I think what I'm gonna do is get a couple quality BMX bikes and make it a 1x7. Then add the front brakes,tires and the other necessities.


Couple of good build threads in here. I wish I had found these forums before. I think there some good kids bikes as a foundation. I would have bought a used Marin, Specialized etc... and just built a really nice bike following some of the advice in here.

But I will say, after seeing my daughter try my son geared bike, glad I didn't go the BMX route. She can't wait for spring to get his bike as a hand me down.


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## jcsnyc (Mar 9, 2008)

Bought my son a Scott Scale Jr 20 today! WOW - what a bike! $340 - so not cheap - but it has real components, is relatively light and just looks awesome.

It has 12 gears, aluminum frame, CANE CREEK headset, etc.

We are riding this weekend - and I am really excited for him.


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## stom_m3 (Jun 28, 2011)

jcsnyc said:


> Bought my son a Scott Scale Jr 20 today! WOW - what a bike! $340 - so not cheap - but it has real components, is relatively light and just looks awesome.
> 
> It has 12 gears, aluminum frame, CANE CREEK headset, etc.
> 
> We are riding this weekend - and I am really excited for him.


Good find. That was my first choice. I was unable to locate one in my area (southern CA) and was told that the 2011's were sold out.


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## NYrr496 (Sep 10, 2008)

My six year old hammers our trails with gears. Sometimes, he forgets to shift going up hills and gets stopped dead in his tracks because he isn't spinning enough gear. I know he'd never be able to do it on a ss bmx bike.


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## Metalhack (Aug 13, 2011)

stom_m3 said:


> Have you figured how you are going to get the rear hub to fit? Also do you know how to weld or have a welder? Have you found a place to buy cable guides, rear dropouts and v-brake bosses? I'm sure you can get them from a custom frame build shop. If you have a TIG or MIG welder, it would be relatively easy.
> 
> If you are going to go the BMX route, I've found that Redline actually sells Flight frames relatively cheap compared to every other manufacturer. Also, the Flight frame is one of the lighter frames out there. Good luck, post pics when you are done.


Actually my side job is I'm a welder. So no problem there.

One idea I want to run buy you all is this....

Do you think it would work if I threw on a 3 speed FD? Running a granny gear, regular gear and a flat or downhill gear. It would be real easy to do. Only thing is I wonder if it would be too big of a spread of gear ratios. Thoughts? And how many gears does your kids use?


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## Metalhack (Aug 13, 2011)

Oh obviously I would have to run a tensioner.

Also I just checked out the Ibex bikes. They seem like a worthy option. Much better spec than the other brands.


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## TwoTone (Jul 5, 2011)

Metalhack said:


> Actually my side job is I'm a welder. So no problem there.
> 
> One idea I want to run buy you all is this....
> 
> Do you think it would work if I threw on a 3 speed FD? Running a granny gear, regular gear and a flat or downhill gear. It would be real easy to do. Only thing is I wonder if it would be too big of a spread of gear ratios. Thoughts? And how many gears does your kids use?


Unless your child is a body builder that wont work. I discovered why MOST kids bikes don't have a FD, they don't have the hand strength to shift from the smaller ring to the larger ones.

It seems that I'm not the only one to have run into this.


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## stom_m3 (Jun 28, 2011)

Metalhack said:


> Actually my side job is I'm a welder. So no problem there.
> 
> One idea I want to run buy you all is this....
> 
> Do you think it would work if I threw on a 3 speed FD? Running a granny gear, regular gear and a flat or downhill gear. It would be real easy to do. Only thing is I wonder if it would be too big of a spread of gear ratios. Thoughts? And how many gears does your kids use?


I looked at the Shimano website and I couldn't find any information on the gear ratio of the 3 speed hubs. It comes down to gear inches and estimating what he will need. On the first couple of rides w/ my son, I found that he uses about 6 of 8 gears. Mostly the easier gears at that. Here are some charts I did when trying to figure out gearing. I found it easiest to go ride your own bike and compare to understand how much force he will have to use to push the gear.

Both charts are gear inches. If you want rollout, multiply each number by pi (3.14).

Here is for my son's mtn bike. I spec'd out a 35t front chainring.










As a comparison, here are 26" (actual size 25.5") tire gear inches.










You can see from the charts that my son's bike has a similar range as a granny gear on a std mtn bike with a little extra umph on the final gear. If you're going to use the 3 spd hub try and find out where the ratios fall on the chart. In general you should look for a 20, 30, 45 gear inch integrated hub. It's a pretty wide spread but I guess that's the difference between old and new cars. Old cars 3 spd, new cars 7. You get better gas mileage with the newer cars.


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## Metalhack (Aug 13, 2011)

TwoTone said:


> Unless your child is a body builder that wont work. I discovered why MOST kids bikes don't have a FD, they don't have the hand strength to shift from the smaller ring to the larger ones.
> 
> It seems that I'm not the only one to have run into this.


Yeah I think your right....

I'm on my way to a friends house to check out his daughters Ibex 24. I'll report back tonight. I'm hoping it fits him well.


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## TwoTone (Jul 5, 2011)

stom_m3 said:


> I looked at the Shimano website and I couldn't find any information on the gear ratio of the 3 speed hubs. It comes down to gear inches and estimating what he will need. On the first couple of rides w/ my son, I found that he uses about 6 of 8 gears. Mostly the easier gears at that. Here are some charts I did when trying to figure out gearing. I found it easiest to go ride your own bike and compare to understand how much force he will have to use to push the gear.
> 
> Both charts are gear inches. If you want rollout, multiply each number by pi (3.14).
> 
> ...


He was talking single speed rear with 3 chain rings up front, not a 3 spd hub, if I didn't misunderstand it.


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## Metalhack (Aug 13, 2011)

TwoTone said:


> He was talking single speed rear with 3 chain rings up front, not a 3 spd hub, if I didn't misunderstand it.


I did indeed..Im not sure if it would work though.

I checked out the Ibex and was pleasantly surprised. I think its the nicest of all the bikes I have looked at(Spec,Trek,Scott,Haro,Giant) and definitely the one with the best spec.

I think im gonna save my time and just go for the Ibex. I thought they were out of business though. Doesn't look it.

Those for all the input.

IBEX Bikes. Alpine youth bikes. Hardtail Mountain Bikes.


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## TigWorld (Feb 8, 2010)

stom_m3 said:


> Have you figured how you are going to get the rear hub to fit?


You don't. Just convert your BMX SS hub to geared. There's a big thread in the 29er forum that shows how to do it.



stom_m3 said:


> Also do you know how to weld or have a welder? Have you found a place to buy cable guides, rear dropouts and v-brake bosses?


What for? The redline frames come with a v-brake on the rear and for cables you use full length gear housing and zipties. For a rear dropout you use a DMR wheel tug with integrated derailleur hanger.


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## NS-NV (Aug 15, 2006)

As a side note, DMR has a chain tensioner/ hanger that will allow you to gear a bmx (if you can sort out the hub).


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## Metalhack (Aug 13, 2011)

NS-NV said:


> As a side note, DMR has a chain tensioner/ hanger that will allow you to gear a bmx (if you can sort out the hub).


Therein lies the problem....all BMX hubs are 110mm, and all gear hubs are at least 120mm with most being 135mm. Though the mods done by Tig prove it can be done...im just not sure if the new Reds come with the same hub.

I think Im just going to get the Ibex for both kids, put 'em on a diet and mod it up a bit.


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## stom_m3 (Jun 28, 2011)

Metal Hack - For the price of the Ibex bikes you can have the Scott bikes. The Scale 20 retails for $380 and the 24" for $420. Ibex is $380/$480 respectively. Also, I don't like the top tube cable routing on the Ibex bikes. You will find standover to be an issue with the younger one. He will be sitting/falling on that top tube a lot. Maybe the same with the older. Good luck. Pics once you have them.


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## TwoTone (Jul 5, 2011)

Metalhack said:


> Therein lies the problem....all BMX hubs are 110mm, and all gear hubs are at least 120mm with most being 135mm. Though the mods done by Tig prove it can be done...im just not sure if the new Reds come with the same hub.
> 
> I think Im just going to get the Ibex for both kids, put 'em on a diet and mod it up a bit.


Again have you looked at any of the build threads? I really wish I had seen them, I would have gone a completely different route on bikes.

I really think for slightly more than a pre made bike, you can build a much better bike.

My 6 year old daughter is getting my son's 20 inch, but I'm building him a 24 inch. The only thing I haven't decided, 13 inch 26wheel frame or get a used nice 24inch frame bike and just replace most of it.

keep in mind, with the builds you can keep moving parts to the next bike. Get decent disc hubs and the can be laced to 20,24 then 26 inch rims.

just a thought.

http://forums.mtbr.com/families-riding-kids/new-sette-reken-build-my-9-year-old-725246.html

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

http://forums.mtbr.com/families-rid...ct-customized-marin-hidden-canyon-581791.html


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## Metalhack (Aug 13, 2011)

TwoTone said:


> Again have you looked at any of the build threads? I really wish I had seen them, I would have gone a completely different route on bikes.
> 
> I really think for slightly more than a pre made bike, you can build a much better bike.
> 
> ...


Yup I have checked out all those builds. They are awesome and definately something I may end up doing. I was just trying to use Redline because I can get them very cheap and they come equipped with some decent parts sized for kids.


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## NS-NV (Aug 15, 2006)

Hands down, BMX has the best components for small bikes. MTB is lightyears behind. The things that cross-over, with the most weight savings, are cranks, rims, tires, seat/post, & if you are really counting grams mini handlebars.

I am part way thru my 5 yr old son's Shred 2.0 project. Pedalling is not a huge issue as most of his trail riding on is gravity fed (I tether him to get up hill).


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## wycough (Mar 9, 2008)

I'm gonna add my build thread to this list because my son did ride BMX prior to this build and it is referenced in the thread.

http://forums.mtbr.com/families-riding-kids/another-performance-access-14-5-build-log-695963.html


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## Metalhack (Aug 13, 2011)

wycough said:


> I'm gonna add my build thread to this list because my son did ride BMX prior to this build and it is referenced in the thread.
> 
> http://forums.mtbr.com/families-riding-kids/another-performance-access-14-5-build-log-695963.html


Yup...nice build.

In fact these small 26" builds with the 24 wheels are great and one that until recently never considered. Im going back and forth of what to do...I have change build ideas and what bike to get no less than 3 times today. I will take my time and consider all the options.

I really think my little one will be best on a SS MX Mini geared low. Hes not going to be hammering hills. In fact he will probably just be riding the local beginner single track loop and campground trails.


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## stom_m3 (Jun 28, 2011)

Metalhack said:


> Yup...nice build.
> 
> In fact these small 26" builds with the 24 wheels are great and one that until recently never considered. Im going back and forth of what to do...I have change build ideas and what bike to get no less than 3 times today. I will take my time and consider all the options.
> 
> I really think my little one will be best on a SS MX Mini geared low. Hes not going to be hammering hills. In fact he will probably just be riding the local beginner single track loop and campground trails.


Not to throw curve balls at you but you should think about the mini BMX thing for your son. My son races an Intense Mini. I checked out his frame quickly and here are a couple of things you may want to consider;

1. The rim diameter on a mini is 451mm vs 406mm. The issue this creates is with the brake reach. You will need to reweld the supports lower to fit a 406mm rim as they are designed for a rim radius 1" larger.
2. Once you get a 406mm rim to fit your brakes, any tire larger than 1.75 will have a difficult time fitting between the rear stays. The front fork will also be an issue as it is fairly narrow as well.

I can tell you from experience when I took my son mountain biking on his BMX mini bike, the tires were just not wide enough. He sank instantly in shallow dirt, lacked grip and overall stability.

Hope that helps with your decision.


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## wycough (Mar 9, 2008)

stom_m3 said:


> Not to throw curve balls at you but you should think about the mini BMX thing for your son. My son races an Intense Mini. I checked out his frame quickly and here are a couple of things you may want to consider;
> 
> 1. The rim diameter on a mini is 451mm vs 406mm. The issue this creates is with the brake reach. You will need to reweld the supports lower to fit a 406mm rim as they are designed for a rim radius 1" larger.
> 2. Once you get a 406mm rim to fit your brakes, any tire larger than 1.75 will have a difficult time fitting between the rear stays. The front fork will also be an issue as it is fairly narrow as well.
> ...


Please reference the below thread link for your issues. Honestly in the Dallas area we had no issues whatsoever with using the bmx for local singletrack with the modifications I have listed. We even rode in Arkansas. No rewelding needed, use adapters. There are tire choices for width. But in my experience 1 3/8ths is fine set up tubeless with low pressure.

http://forums.mtbr.com/families-riding-kids/bmx-mtb-hybrid-project-problem-724867.html


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## Mr.Magura (Aug 11, 2010)

Any of you guys thought of using a 14" DJ frame, and 24" wheels instead of a BMX?

FireEye has some pretty decent offers in that category, and they all sport a rear der. option. 
Like the Shortfuse frame for instance. It is pretty much a BMX with MTB features.

They're cheap too. Chainreaction sells the Shortfuse frame for like 120$, and have good offers for 24" wheels as well.

Magura


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## IAmHolland (Jul 8, 2010)

Mr.Magura said:


> Any of you guys thought of using a 14" DJ frame, and 24" wheels instead of a BMX?
> 
> FireEye has some pretty decent offers in that category, and they all sport a rear der. option.
> Like the Shortfuse frame for instance. It is pretty much a BMX with MTB features.
> ...


The problem with DJ bikes are that they are sized for larger kids/adults. The ETT is usually fairly long. Using a XC bike would be the nearest fit. Appropriate sized kid 24" bikes would have the ETT between 19-20". You can stretch a bit to 21". The DJ bikes will be around 23"-24". On top of that, with FireEye you will have to use BMX bottom brackets and cranks, on the older frames. Some of their newer frames can use MTB Euro BB.


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