[gwhy]

Hiya everyone,
I thought I would start here on this forum ( as I used to be a member about 3 years ago and always found the members to be very helpful). I am looking for some help in finding some dimensions of various trials bikes ( beta is my preference ). I no longer have a bike but when I did ride I thought the beta suited my riding style a little better than all the other makes I owned . For the last year I have been looking into the concept of making a electric trials bike ( like the oset baby bikes but full size ) I know others have converted production bikes to electric but the motors and battery's that are used are very heavy . I think it would be possible to make a bike half the weight ( using a different approach in type of motor/battery's used) of a gas trials bike but with the same/similar power and with quick swap battery packs but would require a custom frame, hence Thats why Im back on this forum. At the moment I am looking at the swing arm as a starting point for the frame and would very much like anyone can tell me the length from swing arm pivot to rear wheel axle. Any help would be appreciated. If anyone is intrested in the progress or has any questions/suggestions then fire away.

Thanks.

[motofire]

What dimensions do you want? I have an EVO and would gladly get you some specs.

Also manufacturers website will have some specs for you.

[gwhy]

motofire, on Oct 21 2009, 09:15 PM, said:

What dimensions do you want? I have an EVO and would gladly get you some specs.

Also manufacturers website will have some specs for you.

evo would be good cheers, at the moment I am just looking for the length of the swing arm from the centre of the back axle to the center if the swing arm pivot through the frame. The beta web site do give some specs like ground clearance,seat height and wheel base which is all good info but no mention about swingarm length. I would like to be able to make a frame with basically the same geo of a production bike if possible.

[matt_urban]

http://www.youtube.c...h?v=fRfqyAwXScQ

using a trials bike frame and parts would be easyest because you just need to fit a motor and some dry cell batterys to keep weight down and fit the low down on the bash plate
if a bike without engine comes up on ebay that would be best way to buy

[gwhy]

it would be the easiest route to take but they are to heavy to begin with. The Denali is ok but still using a big heavy motor and heavy sla battery's so the frame/wheels isnt really upto the job/weight, my thinking is if a custom frame can be made to take advantage of much better battery chemistry's and also using a motor that is even more powerfull but only a third of the size and weight. With a prodution frame you will need a monster motor and monster battery's to really push that extra weight around its a catch 22. Im looking for a complete bike weight of about 30kg Im not sure how heavy the Denali is but its not very powerfull. Im looking to have a bike that will produce the power of a 250/270 ice bike.

[the observer]

Check out this Electric Montesa

[KT250guy]

I am also working on an electric bike however I'm still in the conceptual stage due to lack of funds. As far as a motor goes you may want to try an ETek from briggs and straton, that is what im planning to use.

p.s. thinks for watching my video

[gwhy]

KT250guy, on Oct 22 2009, 04:11 AM, said:

I am also working on an electric bike however I'm still in the conceptual stage due to lack of funds. As far as a motor goes you may want to try an ETek from briggs and straton, that is what im planning to use.

p.s. thinks for watching my video

The ETek is a very good motor and used alot for various motorcycle conversions but it is very heavy and not very efficient the agni is a better motor ( more robust ) but still very heavy Im planning on going a completely different route by using 2 maybe 3 very small ( in size and weight ) but powerfull brushless motors 3 motors will produce about 26hp (and still be lighter and slightly smaller than a ETek) which is more than enough for a trials bike. Im hoping to get away with 2 motors max ( 18hp ) geared for around 25-30mph. The mont in the post a little ways up is a very nice conversion but again is very heavy and with all the trials bike conversions that I have seen and read about they all appear to lack the punch factor that you get from a gas engine and Im sure this is due to the weight. I have also put a fare bit of thought into the controller side of things that it will be possible to program the controller to mimic engine braking and also mimic a clutch ( the controller is in development ).

[gwhy]

I thought I will put up some links to exsiting e-trial bike conversions someone may find them interesting:

http://www.planetetr...?lng=en&pg=9917

http://www.youtube.com/watch?v=wjBdQEESWoQ...player_embedded

http://www.mototrial.net/cutenews/show_new...=&template=

http://www.planetetr...lng=fr&pg=12984

http://www.forster-elektro-trial.de/home/d...1-prototyp.html

[chewy]

Very interesting.I'll bung you a pair of footpegs. I think Ergo nomos are the latin bywords you must keep in mind. Yes you need to match the tourque,(just watch the way top riders use it) It will not be taken seriously if it's not competitive against gas engines. Have you thought about transmisions/clutches flywheels wheight distribution. you certainly have an ambitious project to while away the hours, started my mind spinning. Are you doing this simply for interest or with a view to having a sell-able product? I have been a self employed mech eng. for30 years and riding trials for 40! designing and making machinery. A word of advice commercially. in the world of trials it is not neccessarily technical & ergonomic exellence that makes sales you need to get current top riders and movers/shakers from the "industry" on side. Make sure your design specification is complete BEFORE you start specifying parts. This forum is a very good way to create a specification.

[gwhy]

chewy, on Oct 22 2009, 09:19 PM, said:

Very interesting.I'll bung you a pair of footpegs. I think Ergo nomos are the latin bywords you must keep in mind. Yes you need to match the tourque,(just watch the way top riders use it) It will not be taken seriously if it's not competitive against gas engines. Have you thought about transmisions/clutches flywheels wheight distribution. you certainly have an ambitious project to while away the hours, started my mind spinning. Are you doing this simply for interest or with a view to having a sell-able product? I have been a self employed mech eng. for30 years and riding trials for 40! designing and making machinery. A word of advice commercially. in the world of trials it is not neccessarily technical & ergonomic exellence that makes sales you need to get current top riders and movers/shakers from the "industry" on side. Make sure your design specification is complete BEFORE you start specifying parts. This forum is a very good way to create a specification.

I totally agree with every thing you have said, I have a few contacts ( movers and shakers) but I will not even approach them until I have a bike that can really cut it with a production gas bike which I believe is possible. Yes I have put a lot of thought into transmissions/clutches, multiple gears may not be necessary due to the power of the motors I plan to use as long as the range of the throttle can be switched on the fly ( there will have to be a reduction gear from the motors as the spin upto 10000+ rpm) , the clutch is a tricky one Im not planning on having a true clutch but having a electronic control that can mimic a clutch, again this will very much depend on how well the motors perform in the custom built frame. I am doing this for fun ( hobby ) but I would love to have a sell-able product at the end of it. I will have to see how it goes I have all the parts to make a prototype except a frame. I can see you ride with the kingswood club I have ridden a couple of trials that they have run. I know what a bike should be capable of and in what conditions so I know what Im aiming for. I am from a electronics background and building a speed controller specifically for use on a e-trials bike which will be a first as far as I know. Just need some specs now so a colleague of mine to get started on a frame.

[gwhy]

In need of some more information please. As Sunday's trials and the weekend play time is nearly over I thought there maybe some people taking there engines out of there bikes for maintenance over the coming week. I would be very grateful if someone could tell me the weight of there bikes without the engine fitted or just the weight of there engine. The complete weight setup of electric motors/controller and battery's that I would like to replace the IC engine weighs in at approx 13kg and produces 16hp or add another 2kg for a additional 8hp. I am going back over the numbers to see what will be the overall weight if this electric power plant setup is fitted into a existing trials bike.

Thanks in advance.

[gwhy]

Here is a very nice electric conversion along the lines that I will try to achive with 2 motors but in a trials bike. The motors used in this conversion are large and very heavy but only put out very small power ( about 4hp total for both motors). The motors that I plan on using are about the size of a coke can and produce 8hp'ish for each motor and is a third of the weight, also the battery's used in this conversion are sla's which again are very heavy and large newer battery technology enables third of the size/weight with the same power out. I need frame specs before I can go any further with this.. come on guys :-)

[KT250guy]

You might want to consider larger radio controlled plane motors, particularly the ones used in the aerobatic types, they are really powerful and light.

[gwhy]

KT250guy, on Oct 28 2009, 04:32 AM, said:

You might want to consider larger radio controlled plane motors, particularly the ones used in the aerobatic types, they are really powerful and light.

Yes this is what I have been playing with, they are very powerful , very light and tiny and another bonus is they are very reasonable in price.