Switched to a GNG style "big block" swingarm coming soon!!

[Whiplash]

I don't take it personally but it does increase costs significantly if I require more pivot points, fabrication, bearings, and materials. I see your point I just think with a powered bike it will be FAR less noticeable that's all..

 

[crossbreak]

The e-spire geometry is something to be considered, it drives really nice. Feels a bit bulky, guess mainly because of the large wheelbase, but that's ok since it has power I can measure geometry for you if you like. There is a shop near my house that sells them.

 

[Whiplash]

Well hopefully I'll get my bottle of argon soon! I have a sidejob this weekend and I should have enough saved for the tank after that. That's the last piece of the puzzle and I can start practicing!!

 

[Whiplash]

For what its worth this is the frame that inspired my layout. Its very similar and a very nice looking chassis.

 

[thepronghorn]

For what its worth this is the frame that inspired my layout. Its very similar and a very nice looking chassis.

Notice how that frame has an idler above the chainring that directs the force to be inline with the pivot point and rear axle. Also notice that the pivot point is forward of the bb/axle (closer to the front of the bike). I believe 2moto wants you to incorporate these two features into your design to minimize the effects on the suspension from the chain's force. I don't think he was pointing out the four bar suspension on the conway e-rider as "sensible," he was focusing on the main pivot point which puts it inline with the top of the chainring and the rear axle.

You can still do a single pivot, you just need to move your pivot point downwards. Right now with the high pivot point, the force from the motor will pull the rear wheel downwards and closer to the drive axle, effectively negating the suspension's travel.

 

[Whiplash]

Yeah I noticed the idler and think that is a cool idea if needed. I am still playing around with the pivot point and I'm sure it will change on the bike. I think what I'll do is build the frame minus the pivot point, then build the swing arm and experiment with the height and try to get it as low as possible without getting in the way of the chain... That's my main problem is when the suspension compresses or unloads I fear the chain will hit something. Don't worry his and your advise is being put to use, I'm just not sure how to do it yet..

 

[Whiplash]

OK so I looked this over some more and think this should help. I can move the motor back in the chassis closer to the pivot so it SHOULD keep the chain away from the swing arm I think. This way I can set it at the same height as the pivot when the suspension is at say 25% sag as with a rider on board. I think this will improve the chain problem very much and should be about the best I can do here I think..

 

[panurge]

The main question projecting a full susp. bicycle frame is to combine linear shock travel with a reasonable low ratio and a minimal to no interaction with the chain/s length but still maintaining a good pedal-ability; the pedal action, indeed, has less power than a typical ES motor, but has a bigger vertical component at BB level due to the high torque/low rpm and the non-linear power input and rider weight movement, proper of the human traction.
The less the bike need a pedal ability, the more you can play with setups closer to motorbike-style pivoting....

For single pivots bikes, the position of the pivot is really constrained to a small (would say max 150mm radium) area up and forward the BB point.

Pivot driven Bikes like Brooklin, GT It-1 and some other mostly old models made by famous and non famous brands (nicolai and devinci as an example), have the problem that the distance between BB and pivot cannot be so close, to allow the primary pedal chain to work well, and keep the space for sprockets and stuff....

Another typical issue is the interaction with the Disk Brake that don't allow the susp to work good (or at all) while braking....

I've made a lot of measures/modeling of existing bikes in my life, these are models of the mentioned Pivot drive bikes for instance.....I can send you the original CADS if this can help.....

Cheers

 

[Whiplash]

Excellent info THX!

 

[Whiplash]

OK by moving the motor back and up a little I got the pivot to go from 1.5" of growth on compression to about 3/4". I'm hoping this will be OK since I don't think I can improve it without a LOT of extra effort during construction. The only way I can get it better is somehow making a pivot that does not go through the bike and then I could move the motor back further but for now that's not doable. Basically the hub gets in the way of the bolt going through the frame. If anyone can think of a SIMPLE solution I'm all ears but I don't think there is one..

 

[bØb]

How about putting a tension side idler around the swing arm bolt and mount the motor as close as possible to the SA bolt. Position the motor vertically so that the chain is almost straight at full compression to minimize losses. If necessary put a slack side idler close to the motor to insure proper chain wrap. Make sure the chain does not get off the slack side idler at full compression. Not much for losses there. A simple rub block could keep the chain in the slack side idler at full compression if necessary.

bØb

 

[Whiplash]

That's basically what I want to do, I just don't know how to attach the swingarm in a strong fashion that does not require a bolt going all the way through the bike. The body of the motor will interfere with the pivot mount so I need a simple way to mount the pivot with a "flush" type of pivot mount. I am thinking maybe a turned spacer welded to the outside wall of the main "box" with a countersunk bolt coming from the inside of the "box" with a very thin nut securing the bearing of the swingarm to the side of the bike. I just don't know how strong this would be, I imagine it would be sufficient as long as I use quality hardware. What do you think of that? This is the only way I can think of to get the motor that close to the pivot without some kind of fancy multi link suspension..

 

[bØb]

Just move the motor to where you proposed and add the idlers. Mount the motor as far back as you can and still miss the 1 piece SA bolt. The idler should be around the SA bolt and the tension side of the chain passes over it. Just make sure that the chain still has a little bend in it at full suspension compression. You don't want it lifting off the idler.

If you mount a slack side idler just below the SA bolt and pass the slack side over it, there should be very little change in chain length with suspension travel.

bØb

 

[Whiplash]

Oh OK I understand, that's a good idea! Hopefully the location of the sprockets laterally will allow it to work, if not I'll just have to mount a good strong idler off the frame somewhere..

 

[bØb]

Oh OK I understand, that's a good idea! Hopefully the location of the sprockets laterally will allow it to work, if not I'll just have to mount a good strong idler off the frame somewhere..

If you use a slack side idler, it needs to be on the frame. The slack side idler need not be anything more than a dérailleur sprocket.
If you have trouble getting a idler big enough to go around the SA bolt, you might try using a FW and remove the ratchet paws. I think I found some hub-less FW adapters for 1/2" shafts at http://staton-inc.com/home.shtml

bØb

 

[rodgah]

hey whip a bit of a hijack for a second...

in one of your videos with the motor apart you mentioned you could squeeze the rotor into the stator and you might have to shim them apart? I am waiting for someone to go out and abuse a convert to see where it will fail, but if all goes smoothly I could supply laser cut spacers for the stator and sprockets, maybe even a little metal template to drill the holes in the side cover that locates tightly around the freewheel thread and a BB frame mount :wink: .

Rodger

 

[Whiplash]

That is actually the whole motor assy and it does not get modified, at least I don't think it will. These should be just as strong as before hopefully! Lol!

 

[Whiplash]

I FINALLY got a deal together for an argon tank. Its a 250CuFt tank FULL for $125+a like new 5gallon small compressor I have. Just gotta go make the deal this weekend. Hopefully he won't sell it out under me!

 

[Whiplash]

Woohoo! Got a 250CF tank FULL of argon for $125+small air compressor I never use! I can't believe he did the deal as he made a mistake and sold the smaller tank I was going to get and had to give me this bigger $400+ tank instead since I had just driven 130 miles to get it! SCORE!!

 

[Whiplash]

Gotta love the Prius C I borrowed, 260+ miles on $16 in gas!!!

 

[recumpence]

I was just going to ask you about the car.

I average 45mpg on my C-Max hybrid. I love Hybrids! The little C is the highest mileage car out there right now, IIRC.

Matt

 

[Whiplash]

Yeah its my mothers car but its great and actually fit this big tank no problem!

 

[Whiplash]

Grr! I thought I had the right plug for the welder but its close but no cigar! I'll swing by the hardware store tomorrow and pick up the right one and fire this bad boy up!! Its been like 7 years and ready to weld aluminum!

 

[Whiplash]

Finally got the right plug and got it wired! Still need to dial it in a bit but I'm very close to being able to order metal and go for it!

This little welder has got some balls! I keep having to turn down the amps! I did this on like 35A! These inverters are amazing!

It needs a bit more cleaning and such but this is a decent weld. I also didn't use any post flow so its got some junk at the end...

 

[Whiplash]

Incidentally, I found this bike in another thread that Timma is going to build for his girlfriend and I'm going to try and get as close to this as I can for the swing arm mount. Nice looking bike!