LMX P2 : Freeride trials motorcycle frame development

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bzhwindtalker   1 MW

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LMX P2 : Freeride trials motorcycle frame development

Post by bzhwindtalker » Feb 27 2014 1:59pm

Started working on the LMX P2! Trying to design a good jig in the process.
This is a follow up from : http://endless-sphere.com/forums/viewto ... 28&t=47054
I want to produce some of those frames, first for friends and locals and maybe ship some...

This bike will be designed with the following design ideas : Pedalless, 35-40kg, 3kw continuous, 8kw peak, 20S 10Ah, Air cooled GNG style "big block" (80*50mm rotor), 24" wide trials rear with custom hub, 26" front, pedalless. 200mm front travel, 160-180 rear, single pivot. Switchable rear subframe depending on the riding style (enduro/trials/freeride)

Started CAD work today :
Image

Open to ideas!
Last edited by bzhwindtalker on Jun 25 2014 4:32am, edited 1 time in total.

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christerljung   100 W

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Re: LMX P2 : Freeride trials motorcycle frame

Post by christerljung » Feb 27 2014 2:29pm

Cool idea with interchangable subframes!! 8)
219-chain? What ratio did you have on the blue bike?

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Feb 27 2014 2:39pm

I will likely use #420 chain, as I don't need a lot of reduction! the motor is twice the pole count of the GNG motor so its spins at half the RPM.. on the blue bike I had 11-92 on 14s with the old 70kv motor

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crossbreak   100 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Feb 27 2014 3:39pm

GNG has 8, big block has 12 poles, so 3750rpm max for the GNG and 2500rpm max for the big block.

A rig is a nice place to start with. I have thought a lot about such a frame. IMO you should maximize the space usage between the wheels to get the lowest COG and smallest wheelbase possible. Two KW hours of battery should fit there.. one Kwh of lipo is 7kg and about 5 liters of volume. 2kWh should fit in between the wheels IMO.

I always model my frame with completely compressed front suspension to make clear where the battery should end and the front wheel should start

here is an example, maybe not the best one.. keeping things simple like using a straight downtube is of course more important than using the last percentage of space.
example.jpg
example.jpg (33.84 KiB) Viewed 22952 times

Still, i would want two covings in the downtube, like this nice crystalite middrive frame, keeps things simple and still maximizes battery space:
http://endless-sphere.com/forums/viewto ... 89#p545418
example2.jpg
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Last edited by crossbreak on Feb 27 2014 5:27pm, edited 1 time in total.

Tench   100 kW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by Tench » Feb 27 2014 5:00pm

Funny a pic of my orange specialised should be shown here as I think I have a pretty similar idea of what I want from a bike as Adam and I am also developing a new one at the moment.
I am looking forward to what you do this time Adam, as you can ride and know what you want your bike to be capable of, if you can achieve this and make it Adam proof it will be very good!
Project one http://endless-sphere.com/forums/viewto ... ilit=tench
Project Two http://endless-sphere.com/forums/viewto ... =6&t=37489
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crossbreak   100 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Feb 27 2014 5:25pm

your bike has so many good ideas that are worth to steal :twisted:

here is what i can come up with this evening... i have not thought much about rear suspension though.. front susp is again fully compressed
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example3.jpg
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Tench   100 kW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by Tench » Feb 27 2014 5:38pm

You don't need to steal them, it is on here to share, if something you see gives you any ideas for your own build go ahead and use it.
I have learnt so much from the ES members myself I am glad if I can give a bit a bit back.
The one I am doing now is better though! :shock: :lol:
Project one http://endless-sphere.com/forums/viewto ... ilit=tench
Project Two http://endless-sphere.com/forums/viewto ... =6&t=37489
The uk's first Stealth Bomber

There is a box inside your head, inside amongst others are the words "Wont fit" stop looking for answers in the box, there are no answers only excuses.

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Feb 27 2014 5:50pm

haha my first drawing was so wong, the frame would have been traped on the jig when welded :mrgreen:
Image

Designing with the suspention compressed is a good idea for clearances, I will do some tests and adjust.

Here I am looking at using a swingarm from a crF 50 because they are cheap, even for CNC AL ones... Dunno if it will fit the 24" rear I have in mind!


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crossbreak   100 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Feb 28 2014 5:12am

Nice! I like the swing arm a lot. Rear brake mount?

I'd like to see how this may look in the end.. a pic with wheels and fully compressed suspension would be nice.

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Re: LMX P2 : Freeride trials motorcycle frame

Post by pchen92 » Feb 28 2014 5:27am

subscribed :D 8)
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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Feb 28 2014 5:56am

The rear swingarm is one of those, http://www.minimx.fr/pieces-detachees-d ... -bike.html quite cheap alu pit bike swingarms. I found the model online 8)
Using it would reduce cost and complexity of the project big times, so I hope it would fit a wide 24" bike trial wheel.

I called the guy from bht ebike, he can get me nice things from china and discounts on shipping and bulk if I get 10+ units :wink:


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crossbreak   100 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Mar 01 2014 5:45am

The 200mm wide swing arm would need a lot of spacers.. which does'nt make it any stiffer. I'd prefer a more narrow swing arm.

Additionally, it is only 400mm long. So a 24" wheel will not fit I guess. Have a look at this one:

http://cenkoo.de/shop/product_info.php?products_id=888
Image
it's 450 mm long, has 295mmradial tyre clearance. It's made for 14"x3.0" moped tires just like the one you fount....It would still fit a 21" bycicle tire. A 24 x 2,35 (60-507) tire wouldn't..besides it would look funny since a 2.35" tire is quite narrow.



Which rear hub? 142x12mm shimano through axle hubs are not that expensive. They start at 40€.would need a custom swing arm.. maybe a Moped hub would be even cheaper, I guess they have 36 spockes as well.

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Re: LMX P2 : Freeride trials motorcycle frame

Post by scorpionice » Mar 01 2014 12:29pm

just a fan... :D subscribe

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Mar 01 2014 12:32pm

i searched about an hour for alloy swing arms made in china that fit wheels larger than 14 inch moped /20" bicycle. I found almost nothing that really suits our needs.

I dont want a 20" rear wheel.. looks like I have to built my own swing arm :( We could merge your needs and maybe save some money.

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Mar 01 2014 12:40pm

The swingarm model I have fits a 24 rear with a big tire, so those must exist... I don't want 20" rear either!

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Re: LMX P2 : Freeride trials motorcycle frame

Post by crossbreak » Mar 01 2014 12:56pm

for a 24" wheel we need about 32cm tyre clearance. the alloy one you posted above has >30cm clearance as I "measured" from the pics.. maybe something we should buy and try.. if it doesn't fit we still can send it back :D

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Mar 01 2014 1:07pm

We need to find a source for this particular swingarm : https://grabcad.com/library/rear-swinga ... 10-140cc-1
Seems to work OK with a 24"


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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Mar 02 2014 12:27pm

I weigthed the LMX P1 today, 37kg. The goal for the next frame is to stay under 35kg!

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Joe T.   100 W

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Re: LMX P2 : Freeride trials motorcycle frame

Post by Joe T. » Mar 04 2014 1:15am

The swing arm I made for my bike has replaceable dropouts. They bolt into receivers that face back and in-line with the chain. After I was done I realized I can change the wheel base by making longer or shorter dropouts. This was not planned in the design at first but it's nice to have options.

Perhaps you can take a "store bought" swing arm like the 50cc and just make extensions that bolt into the axle mounts that are there.

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Re: LMX P2 : Freeride trials motorcycle frame

Post by AussieJester » Mar 04 2014 1:24am

Perhaps you can take a "store bought" swing arm like the 50cc and just make extensions that bolt into the axle mounts that are there.

^^^^exactly what I would be considering

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Mar 04 2014 2:34pm

Image

Image

Image

Taking great shape! I need to add some bracing up front. I want to start working on the jiig this weekend :)

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bzhwindtalker   1 MW

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Re: LMX P2 : Freeride trials motorcycle frame

Post by bzhwindtalker » Mar 04 2014 3:02pm

Unsure about how to brace this baybe... advice?
Image

Image

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