Direct drive and nonhub motors in a FS bike

[grwsaltspring]

I'm a bit late in on this party and have to admit that I haven't read all of the threads, so if this has been discussed before a link to the applicable thread would be welcome.

I'm interested in a two wheel direct drive set up like the ones GGoodrum is pursuing. I like the simplicity of the Grinhill builds. The elegance of the Moulton build, of Miles, is inspiring.

Besides Miles and Deecanio, (and I'm unclear if Deecanio's is a DD) are there any other full suspension RC motor builds here?

Is it possible to do a "simple" DD to the rear wheel on a full suspension bike that is not a unified rear triangle?

I may be barking up the wrong tree here, but just trying to understand how this might work.

Cheers Greg

 

[MitchJi]

Hi,

So far Gary's builds are to a geared hub (right hand drive) so he gets the advantage of gears.

D's build is to the cranks so he gets the advantage of gears and suspension travel isn't much more of an issue than pedaling.

Here is a left side DD build (if you read through the second thread you will see that he would have preferred more reduction):
http://endless-sphere.com/forums/viewtopic.php?f=3&t=5156
http://endless-sphere.com/forums/viewtopic.php?f=6&t=5168

For DD you probably want to either mount the drive components on the rear swing-arm or near the BB.

 

[boostjuice]

It all depends on the dynamic suspension geometry of the bike in question. If you want to mount a motor/drive on the frame to avoid unsprung weight whilst driving the rear wheel direct then you must have zero tensioned chain growth between it and the sprocket on the motor (For a single stage drive). It should not require lengthening or shortening through the entire movement of the rear end suspension under compression.

For most full suspension bikes, this unsprung motor/drive mounting is not possible as the only way for this to occur is by placing your motor where the primary suspension pivot point is (usually a bolt/bearings through a reinforced section of frame). Rather, a two stage reduction that utilizes a jackshaft built upon the primary suspension pivot point is needed to allow this (On a few select bikes the pivot point is built around the BB shell using large ID bearings, in which case a pedal cadence reduced drive feeding freewheel cranks is preferable but often impractical due to the added reduction needed and increased losses).

This then begs the question... How does the crankset power the rear wheel whilst avoiding chain growth?

Most full suspension bikes either place the BB in the unsprung rear section of frame - avoiding chain growth, or just forward of it so that there is indeed a slight amount of chain lengthening or shortening required between the crankset and rear cluster. This is usually ok though as the rider is unlikely to be pedaling when landing large jumps and if they are pedaling over rough terrain, human power is much less than a motor which would place far more damaging tension force on the chain if the wheel couldnt slip to accomodate it.

Miles' Low Kv belt drive and Liveforphysics RC direct drives all place the motor within the unsprung section of rear frame to avoid these power transmission complications, and this is indeed fine for the low weight RC equipment. It further helps If the motor is mounted close to the pivot point as it then reduces the leverage effect of the unsprung weight.

So if you want to do this, find a bike that has enough room for an RC motor and mounting brackets to fit neatly within the rear unsprung frame section that also allows clearance for the driving chain to avoid fouling the frame when running to an extremely large wheel mounted sprocket. If you can fit the motor in the frame then it saves having to build a custom, high strength panner rack which the motor would be bolted to. Big aesthetic advantage, lowers the centre of gravity and is less of a PITA.

 

[grwsaltspring]

Thanks for the replies guys.

The donor bike would be a Maverick Matic, which I believe to be a version of URT.

http://www.maverickbike.com/user_files/file_399.jpg

An alternative suspended Trike I've been contemplating is this.

http://www.actionbent.com/Images/T1X/t1xfullsidegrass.jpg

Time for me to do some more reading and research on the topic.

Cheers Greg

 

[Miles]

Thanks for the replies guys.
The donor bike would be a Maverick Matic, which I believe to be a version of URT.

Hi Greg,

Seems to be a modified URT, like the GT iDrive (though quite different). The BB will move with respect to the main frame and rear triangle.... Strictly, I'm not sure you should call this one a URT.....

 

[grwsaltspring]

Thanks Miles.

I guess that was why I suggested that it was a "version" of a URT. Any thoughts on what to call it?

Seeing it stripped of its BB makes me wonder if it is in fact such a good candidate for an RC build unless I can mount a motor behind the shock, on top of the rear triangle.

I guess I got excited by the potential low weight of the RC builds on a XC bike.

Any thoughts?

Cheers Greg

 

[MitchJi]

Hi Greg,

Thanks for the replies guys.

The donor bike would be a Maverick Matic, which I believe to be a version of URT.

Time for me to do some more reading and research on the topic.

Cheers Greg

Luke's layout (you will probably be building a less powerful system ) would work with a URT or non-urt equally well:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=8347

Seeing it stripped of its BB makes me wonder if it is in fact such a good candidate for an RC build unless I can mount a motor behind the shock, on top of the rear triangle.

The bike in the photo Miles posted looks like it has pivot points both in front of and behind the BB. If so there will be chain length changes between the frame and BB and between the top of the rear triangle and BB.

Maybe you want something like a Kona Bass, Kona Cowan DS (same as the Bass) or Haro Sonix?

The Kona's have more room in the Triangle for batteries.

 

[grwsaltspring]

Hi Mitch;

Yes I agree that the Kona is a reasonable layout for a build. (the other bike I have at my disposal is a Turner 5 spot)

I had previously been thinking along the lines of a BMC hub motor in the Maverick with reasonable room in the triangle for batteries, but even that seems heavy now.

I may just drop the whole notion of a FS bike build and explore a trike build and save the bikes for off road riding, though I seem to be favouring my Gary Fisher HiFi these days.

A much more modest trike build than the one Matt is doing, but that wouldn't be very hard. IE more modest :wink:

Thanks for your input and ideas.

Cheers Greg

 

[Miles]

Hi Greg,

I think I would do the trike, for your first project. We need a new breed of frames for power-assisted FS....

I'm not sure what you'd call the Maverick layout. If the BB was fixed with respect to at least one element in the rear triangle then you could say it was a modified URT......

 

[MitchJi]

Hi,

I'm not sure what you'd call the Maverick layout. If the BB was fixed to at least one element in the rear triangle then you could say it was a modified URT......

Here's a picture:
http://www.thebikeboutique.com/product_info.php?products_id=746

Maverick Matic Frame Detail

 

[grwsaltspring]

Thanks Mitch. I've been looking at Grinhills build and wonder if that might not be the way to go if the motor would fit behind the shock on the Maverick.

Miles, Funny you should comment on the need for a "new breed of frame for power-assisted FS..." My back ground is in Architecture. I've been designing and building houses, boats and furniture for a while now. Over the summer I started a program in Industrial Design and one of my classmates wanted to know why I was in the program. My reply, "I want to design an electric bike frame that is set up to accommodate batteries". (Just about ready to roof the new workshop on the property, should be plenty of space to try out a few different projects.)

I think your comment about the trike for my first RC build has merit, particularly as I have the fantasy that I may have the skills to build a removable shell for wintertime rain protection. I was recently approached about becoming involved with our community transit advisory committee, after mentioning that I thought the thing that was missing on island was covered parking for bikes when it was raining. So we will see where this all goes.

Well I've blathered on a bit more than I intended, probably spending too much time designing and not enough talking to people at the moment.

Cheers Greg

 

[deecanio]

very interesting blathering tho Greg
i've been thinking with all the amazing kmx builds going on at the mo that this could be the next logical step.
Firstly i must say that the kmx's have grown on me a LOT since i first joined ES but now i'm looking at them and thinking wouldn't it be uber cool to have any of the Karts shown but with four wheels and a enclosing canopy to cover driver/rider/s and all the electrics, heck that would be something i would buy from one of our peers here for sure.
having four wheels could make for two seats, with weather protection and the kind of range that the guys are getting it could be one of the best things built here on ES by a mile, practically a super fast electric car for under 5k GB, awesome.
i know we already have velomobiles etc but this would be different, a 4 wheeld kmx with clear perspex like canopy, maybe even plastic doors
Oh man i have to stop thinking about this, or build it
OMG "DeeMX" :lol:


D

 

[Miles]

OMG "DeeMX" :lol:

:lol:

 

[Grinhill]

"I want to design an electric bike frame that is set up to accommodate batteries".

Greg, have you had a look at Hal9000's frame?
http://www.endless-sphere.com/forums/viewtopic.php?t=8446#p127881

Haven't heard how he is progressing recently.

 

[Miles]

Yes, I clean forgot about Hal's Mk2 frame

 

[MitchJi]

Hi D,

i've been thinking with all the amazing kmx builds going on at the mo that this could be the next logical step.

Firstly i must say that the kmx's have grown on me a LOT since i first joined ES but now i'm looking at them and thinking wouldn't it be uber cool to have any of the Karts shown but with four wheels and a enclosing canopy to cover driver/rider/s and all the electrics, heck that would be something i would buy from one of our peers here for sure.

having four wheels could make for two seats, with weather protection and the kind of range that the guys are getting it could be one of the best things built here on ES by a mile, practically a super fast electric car for under 5k GB, awesome.

i know we already have velomobiles etc but this would be different, a 4 wheeled kmx with clear perspex like canopy, maybe even plastic doors

OMG "DeeMX"
D

How about "Dee-Vette â„¢"?

Have you checked this site?:
http://www.ffrtrikes.com/home

We hand-build our high-performance electric recumbent trikes right here in the USA. These beautiful vehicles corner on rails and accelerate like banshees, can be taken on and off road, can still haul a load, and are practical enough to be driven to work everyday while just costing pennies to operate! Once you ride one, you wonder why you ever rode anything else.

http://www.ffrtrikes.com/electric_trikes

Faster, further, better. We are building electric vehicles that are at the cutting edge of this technology. With ranges of up to 100 miles per charge and power capabilities of up to 12,000 watts, all while tipping the scales at less than 95 lbs, these trikes are silently pushing the envelope of what's possible.

While they have plenty of amazing technology to talk about, they are also very practical. Depending on the setup, they can be legally driven on the roads in most states with no need for registration, licensing, or insurance! What's even better is that they only cost pennies to operate.

I think the main thing missing is the weather protection.

 

[grwsaltspring]

Interesting that you guys should be talking about weather protection.

Lately my boat building exploits have lead me into composite construction builds. Stitch and Glue, 4 -6 mm ply encased in epoxy. Light and strong.

I've built a couple of kayaks and a 14' runabout as a test case for a a bigger boat. (the new workshop could accommodate a 35' boat, though the next project is likely to be about 25')

But I digress.

The point is that I think that I may now have the skills to build a light weight removable fairing for a trike. Particularly if we go to the next stage this winter of vacuum bagging.

Along with this I've begun exploring making blown Plexiglas fairings. The technology is readily available for both these processes in a home workshop

I haven't gone beyond 3 wheels simply because at this stage of my understanding, if I start to cross the line from electric bike to electric M/C the government constraints seem easier to deal with for 3 wheels than 4.

In thinking about a two seater the motorcycle analogy seems an option worth exploring too. But I'm way ahead of myself at the moment.

Additionally, I have a personal interest in a suspended trike. My partner had her spine fused as a young woman (I guess she is also pushing for a covered, heated version )

So things are kind of converging.... good fun.

Cheers Greg

 

[grwsaltspring]

Oh and yes I'm familiar with Greyborg's build.

A bit heavier than I was hoping for and with a hub motor. Been there done that. This is the attraction of the RC motor builds to me.

IE Is it possible to develop a relatively simple light weight system for a FS XC bike?

Greg

 

[Miles]

Oh and yes I'm familiar with Greyborg's build.

His latest design has the suspension pivot co-axial with the bottom bracket - more suitable for crank driven set-ups...

 

[grwsaltspring]

Thanks for that Miles. I hadn't looked in recently.

Cheers Greg

 

[MitchJi]

The point is that I think that I may now have the skills to build a light weight removable fairing for a trike. Particularly if we go to the next stage this winter of vacuum bagging.

Along with this I've begun exploring making blown Plexiglas fairings. The technology is readily available for both these processes in a home workshop

I hope you do it (and sell them if they turn out well and are affordable)!

I haven't gone beyond 3 wheels simply because at this stage of my understanding, if I start to cross the line from electric bike to electric M/C the government constraints seem easier to deal with for 3 wheels than 4.

I agree.

Additionally, I have a personal interest in a suspended trike. My partner had her spine fused as a young woman (I guess she is also pushing for a covered, heated version )

Cheers Greg

Somewhat OT but I really like this tilting suspended trike (Motorcycle):
http://www.tiltingmotorworks.com/default.asp

 

[grwsaltspring]

Cool picture Mitch.

Is that a V-Max?

Greg

 

[deecanio]

Hi Mitch,

i had seen an FFR trike, i think posted by VRdublove? is he associated with the site at all do you know?
it occurs to me that they could be made pretty slick with some cocooning, not to mention weatherproof, i know that Cedric Lynch has an amazing vehicle in roughly the same format that is capable of hundreds of miles with an agni, shit load of batteries mind which are inside the "velo" but still a very impressive vehicle nontheless.
if i had something even with a range of say 60 miles i'd be happy, Matts kmx's are sweet with awesome power, i was thinking a twin 3220 would be nice but it's more the "bodying" that interests me, a lightweight fast waterproof vehicle, dont even know how i'd use it just that it appeals - like that velo knoxie posted up that looked like morks flying egg :lol: just sweet imo.

D

 

[MitchJi]

Hi D,

He has a thread for the Trike. He purchased the drives and motors from Matt:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=12330

I posted the link and the quotes on his site because you mentioned using e-trikes for transportation and he also talks about that.

A trike like that with weather proofing would be very viable year around or most of the year transportation in most of the world.

 

[MitchJi]

Hi Greg,

Cool picture Mitch.

Is that a V-Max?

Greg

Yes. Sorry I just fixed the link (it was enclosed in image tags by mistake).

A canopy something like one of the following would be great (IMO):