LMX P2 : Freeride trials motorcycle frame development

bzhwindtalker

bzhwindtalker

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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/viewtopic.php?f=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 :
1977531_10152267286974617_601768510_o.jpg


Open to ideas!
 
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
 
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.

View attachment 1


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/viewtopic.php?t=37489#p545418
example2.jpg
 
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!
 
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
 

Attachments

  • example3.jpg
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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:
 
haha my first drawing was so wong, the frame would have been traped on the jig when welded :mrgreen:
1966528_10152267743644617_1306812126_o.jpg


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!
 
The rear swingarm is one of those, http://www.minimx.fr/pieces-detachees-dirt-bike-pit-bike/272-bras-oscillant-acier-cross-430mm-dirt-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:
 
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
schwingarmXB33black_2.jpg

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.
 
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.
 
We need to find a source for this particular swingarm : https://grabcad.com/library/rear-swingarm-for-mini-moto-pitbike-chinese-110-140cc-1
Seems to work OK with a 24"
 
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.
 
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.
Click to expand...


^^^^exactly what I would be considering

***subscribed**

KiM
 
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