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Oset 12.5 Frame Mod

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HI, I'm Travis, got my son, Adler, a 12.5 about 9 months ago. He was 2 yrs 9 months when we got it. We had just removed the training wheels on his 12" bicycle a week or so before the Oset arrived. He is now 3.5 yrs.

I have a small bicycle shop in Louisiana, USA. Also have a very small fab shop in back set up for small volume frame building.

Right out the box it weighed 51lbs. Immediately changed:

-Bars and stem to 31.8 clamp MTB stuff.

-Swapped brake cables to teflon coated wires with shorter lined housing. Better Pads. Very shortly swapped the whole front assembly for a cheap Avid one, HUGE improvement. Removed one of the springs from the rear brake to lighten the action (as long as cable is in good condition it returns fine).

-Stock grips are comically oversized, installed my favorite thin motorcycle grip, Galindo F1.

-Spun rear shock preload adjuster all the way soft so the rear shock was bottomed out all the time (boy has short legs).

-Lipo batterys. 6cell 5aH. Anderson powerpoles.

At this point it weighed 40lbs.

8hIps.jpg

Turns out they don't make MC safety gear for two year olds.

Then I am looking at the heavy plate steel making up the battery tray part of the frame and thinking that it is not needed.

fybU2yX.jpg

I could just cut it out and put some straight tubes in place. Easy and would save a ton of weight. Once I had the frame apart I couldn't help but replace the plain headtube with a fully machined integrated chromoly one I had lying around. Might as well put a little bend in the new downtubes for style.

ZBOyHs2.jpg

Last minute idea to add the 1/2" tube gussets everywhere to give it that Ducati trellis frame look.

AneSX3N.jpg

Getting prepped for paint now, not sure what color I want, something distinctive for sure. When it goes back together it will get a Kelly programable ESC, Magura pot throttle. I have replaced the cast rubber grips on all his bikes with Lizard Skinz 1.8mm thick super grippy handlebar tape. Basically I will have everything done but the rear shock swap to dual air and am investigating disc brakes now.

Here is a pic of his road racer that I just built and he hasn't ridden yet. It's a Razor PR200 with kelly controller, magura ESC, and the thin bar wrap for grips.

39FdS7d.jpg

I will post a pic of the Oset when reassembled. I expect it to weigh 35ish lbs. I am also removing the kickstand and mount from the swingarm. Also swaping the handlebar for a carbon one.

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I like what you have done with the frame... top job, but what about a bash plate ?

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Damn. Can't wait to see what he gets when he's 5! When I was a kid, I had to borrow our lawn mower motor for my mini bike. Anchored it with plumber's tape. Good to go.

So when are you ordering the carbon Marchenisi wheels?

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Excellent!

What I love about these OSETS is that they are a GREAT platform to tweak to make make them fit ones needs.

Are you gearing him towards MX?

My son got his 12.5 at 3yrs 3months. Before that he was on a balance bike at about 2.5 then the first moto was a Razor MX350, then moved his onto the OSET. He is now 4yrs 3months at 39lbs. He out grew the 24v power so I fitted the 12.5 with the electronics from another 36v 16'' I bought to play with him. He rides it at full power, with the 500w motor. Its an impressive little machine. Last time I checked he was exactly 3.3ft, maybe about 3 weeks ago. He is now at the tipping point of being to big for his 12.5, but the 16'' still to big.

We ride strictly MX, and is currently competing. I am making a hybrid between the 12.5 and 16''. GWHY has been extremely helpful in making this right.

ANYWAYS sorry for this long story but wanted to share another little guys story that might help in your project.

I'm all about having a bike for the little ones that fit THEIR scale. Makes it FUN for them and best of all it builds their confidence.

When he was just 3.5 we were at a local track and rode a friends pw50, he got around the track, but you could immediately tell the difference in his confidence level. On the OSET he could literally go anywhere. He was maybe 33lbs then... on a 85lbs pw50! I would not like to ride a 550pnd MX bike :).

Kudos on the frame mod. Lighter is better!

Edited by awdrocks

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I didn't realy think about the lack of a bash guard but we do mostly MX type freeriding around the yard so the weight loss should be more important.

I HATE painting but wanted it to look good so it is taking forever. I've put nearly as much work into the paint as I did the frame mod.

Problem: I can't stop making mprovements. I removed the kickstand and mount (this is a performance vehicle). Rear disc brake is going on now and while I had the swing arm apart I figured I'd cut away some extra metal. I'll post pics once the disc caliper mount is welded in place.

The two biggest problems this bike faces are the 6lb motor and probably 7lb fork.

If I go any further than just the brake on the back end it will mean a total scratch up swingarm and swingarm mounts to house the new motor.

Fork is almost a bigger issue as there is nothing that will bolt on this small of a bike. Cutting a real fork down doesn't look to easy nor does making one from scratch. I do have an old Hanbrink gravity bike fork, double triple trees, made for a 20" wheel, 20mm front axle. Cutting it down is possible but my machine skills are not up to doing internal threading so would need a pros help.

If I did the fork and swingarm this thing would be well under 30lbs.

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I didn't realy think about the lack of a bash guard but we do mostly MX type freeriding around the yard so the weight loss should be more important.

I HATE painting but wanted it to look good so it is taking forever. I've put nearly as much work into the paint as I did the frame mod.

Problem: I can't stop making mprovements. I removed the kickstand and mount (this is a performance vehicle). Rear disc brake is going on now and while I had the swing arm apart I figured I'd cut away some extra metal. I'll post pics once the disc caliper mount is welded in place.

The two biggest problems this bike faces are the 6lb motor and probably 7lb fork.

If I go any further than just the brake on the back end it will mean a total scratch up swingarm and swingarm mounts to house the new motor.

Fork is almost a bigger issue as there is nothing that will bolt on this small of a bike. Cutting a real fork down doesn't look to easy nor does making one from scratch. I do have an old Hanbrink gravity bike fork, double triple trees, made for a 20" wheel, 20mm front axle. Cutting it down is possible but my machine skills are not up to doing internal threading so would need a pros help.

If I did the fork and swingarm this thing would be well under 30lbs.

So what would you do for a motor to reduce the weight while keeping the power?

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My favorite motor, have been wanting one for some other projects for a while, is the Amp Flow A28-150.

Weighs 3.8 lbs rated at 2250watts 6000rpm $300. Stock motor:

Weights 7 lbs rated at 500watts 2600 rpm

Would be so much power that the rpm wouldn't matter. All of the smaller motors that don't make as much power also spin much faster and would have to be geared down increasing the weight and complexity. I would just go for the AmpFlow and build a new swingarm around it.

I built 20" freestyle BMX bike with the 900 watt variation of the stock Oset motor run at 48v so 1800 watts. Weighed 35lbs, went 33 mph, was built to dirt jump and ride at the skatepark (built to crash). It's biggest problem was the heavy motor and I have been wanting to redo it with an AmpFlow motor just haven't ordered one yet, now I need two. Kelly controllers in the bikes now should work fine on the AmpFlow motors and are good for 100 amps (at 50v that is a lot of power!)

7qz9g.jpg

Link to gallery of the E-BMX

http://imgur.com/a/j9kBx

It is a 2007 Terrible-One Garret Brynes frame with a 21.25" top tube (they used to be made here in town). A little long and overbuilt so seemed perfect for this. Foot pegs from XR50 aftermarket.

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a brushed motor is always the best for simplicity but not the best for weight, power and size.

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The AmpFlow is the highest perforance brushed motor I could find. Do you or anyone have any suggestions for motors for the 12.5? Not opposed to brushless.

I got some new endmills and drillbits today so I started the rear disc caliper mount and drilled out the rear sprocket, that thing was heavy. Need to paint it gold.

pWveZvT.jpg

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There is a rather nice brushless motor that have started to prove itself, the only problem is that it comes in a e-bike conversion kit but it have been sourced to here ( so far ) http://www.mistertao.com/taobao-products/taobao-item-15940174178.html I know people that have bought from this site but not all puchases have gone smoothly ( things like P+P ended up a lot more than advertised ) this motor have been proved to be able to handle and be reliable upto around 3kw ( without the fan ) . It weighs in at just under 1kg.

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I didn't do a before and after weight of the sprocket but it feels like it lost about 30-40 percent of it's mass.

The frame mod shaved about three lbs off. Kickstand and mount about a pound. Rear brake mod is going to be good for a few ozs as well. Bike came out the box at 51 lbs, weighed 40 when I started this last round of mods, hoping it weighs about 35 when done. Just need to finish the rear brake mount and paint everything and I'll put it back together and weigh it.

Getting that boat anchor of a motor off the bike is next. Thanks for the motor tip, I like the weight and power is about right for this bike, hate to have to buy brushless controllers though.

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There is a lot of people use this controller http://www.ebay.co.uk/itm/48V-600W-brushless-controller-for-E-bike-scooter-/300352534034?pt=LH_DefaultDomain_0&hash=item45ee67f612 its about one of the best for the price as it can also be programmed ( as standard can up the power to around 2.5kw via programming ) but will need to solder the programming header into the controller.

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Thanks for the motor/controller leads, both are very affordable compared to the stuff I was looking into. I have always wanted more programming options than the Kelly brushed controllers I have. Someone yesterday was telling me about all the options on their R/C planes controller and I guess I need to step up to brushless to get that.

I was hoping for more info on that motor like rpms etc, can you point me to the kit this motor is a part of?

This is lifted directly from the page the motor is on:

Tips:

OUR baby are many kinds, different packaging, singlet, so shipping costs will be based on the quantities and types of pro-purchased accounting pro who shot the baby before contact with the store first estimated freight, such as after delivery, combined with the actual shipping costs Duotuishaobu. Your parents are aware of.Logistics of the baby, transit time may be longer, please be patient, inconvenience, please understand.

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Here is a link to the full kit http://www.gngebike.com/450wbrushless.htm , I think the mistertao site is a reseller, think they buy through the chinese ebay ( equivalent ) then resell to the rest of the world , I think this is why there seems to be so many problems with pricing and descriptions.

the Motor is about 4-1/2 inches diameter and about 2-1/2 inches wide and around 70kV ( 70 rpm per volt )

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