bike to scooter to recumbent (new project)

lowracer · Oct 27, 2013

I re-engineered the powertrain on my scooter conversion. It handles really well and is smooth, fast and quiet (powered by a Mitsubishi 43cc 2 stroke). I had an idea to change this into a front wheel pedal drive MBB (Moving Bottom Bracket) recumbent keeping the same rear engine powertrain. So basically 2 independent drivetrains both which freewheel. The pedal power will only get it up to about 16 mph or so (small wheels), but under engine power in an aerodynamic position, should be pretty exciting. I am searching now for a throw away donor bike which I'll cut to use only the rear triangle and seatpost. I'll use my hugh jass seat as the recumbent seat bottom (nothing more comfy or huge. I gotta brainstorm for a backreat & mount idea. Here are a few pics of what I'm getting at (last pic isn't mine, but is an MBB).
-lowracer-

Dan · Oct 28, 2013

Man, bet that is gonna be a fun ride, LowRacer.

atombikes · Oct 28, 2013

This is my moving bottom bracket recumbent bike. To keep weight down, I have not motorized it. I use it as my "normal" bike. Once I am too old to power it under my own power, I will probably add an electric hub motor to the rear wheel (actually a front wheel so the hub is cheaper) and strap the batteries under the seat.

lowracer · Oct 28, 2013

atom,
I like it...
I've seen some folks flipping the fork around for more trail & better high speed handling at the expense of poor slow speed handling (floppy).
Was initial steering an issue for you due to pedal input effecting it?
I've owned a few different recumbents back a few years now, but none were MBB.
I owned a Lightning F40 and rode it all over the place fully faired (that was a trip!).
-Low-

wheelbender6 · Oct 28, 2013

I've seen a lot of recumbents, but never the moving BB style. It looks very maneuverable compared to the long boat styled recumbents.

lowracer · Oct 28, 2013

This MBB made in France by Zockra is probably the nicest of the ones I've surfed.
Mine won't be quite like that one...lol
-Lowracer-

atombikes · Oct 29, 2013

lowracer said:
atom,
I like it...
I've seen some folks flipping the fork around for more trail & better high speed handling at the expense of poor slow speed handling (floppy).
Was initial steering an issue for you due to pedal input effecting it?
I've owned a few different recumbents back a few years now, but none were MBB.
I owned a Lightning F40 and rode it all over the place fully faired (that was a trip!).
-Low-

lowracer,
Yes, I played around with the trail for about a year until I got to that happy medium. I am around 68 deg headtube angle and about 1-1/2" positive trail. The think about Moving Bottom Bracket design is that pedaling motion induces odd steering behaviour so you have to get used to it. Many people try MBB and decide it's not for them; they probably just give up too fast.

Since I built mine myself, I decided I'd stick with it....

wheelbender6 said:
I've seen a lot of recumbents, but never the moving BB style. It looks very maneuverable compared to the long boat styled recumbents.

Yes, one of the reasons I love my MBB and will keep it for life is that it is so nimble. Other advantages are it's comfortable, easily transportable, it's lighter than other recumbents, can use standard components...and the list goes on.

lowracer · Oct 29, 2013

atom,
I'm still hunting a donor bike. I found one that could have worked, but decided to wait for a better one.
I think I got the seat idea ironed out.
I'm either going to mount the 'Hugh Jass' saddle on the toptube or use a steerer stem coming forward off the seatpost to mount the bottom part of the saddle just over the toptube. Then extending upward behind the saddle will be the seatpost for mounting the backrest (long double saddle in last pics).
Seems like in the saved pics I've collected of short wheelbase recumbents, the seat bottom position is more forward than on a 'normal' std bike.
-Low-

lowracer · Oct 30, 2013

I started messing with the saddle mount today and this is what I came up with so far.
I can then mount another lond saddle to the black cut stem rear section for a sturdy padded backrest.
I may want to get the seat lower and was thinking abount flipping the clamps around or flipping the silver seatpost mount for a dropped angle.
-Low-

lowracer · Oct 31, 2013

Here is another way to mount the bottom section of saddle directly to the top tube of the frame. I kinda like the way it looks and the lower position. This pic is a clever MBB posted on the Instructables website.
-Lowracer-

lowracer · Nov 1, 2013

Here's what the seat looks like mounted to the top tube directly. I will probably cut & wrap an old 700c tire around the top tube where the seat gets clamped down on it for top tube protection & to raise it slightly (good vibration dampener too). I'm still looking for the donor bike. I found two yesterday but both had the large bmx/cruiser style one piece carank/BB's which I dont want to use.
-Low-

lowracer · Nov 3, 2013

I played with the seat & seating position some more today & decided to mount the seat on top of the normal seatpost but with the seatpost turned forward and with the seat slid all the way forward on its rails (pic1). I started messing with the seatback and vice-gripped some angle aluminum onto a rear cross member between the two brake posts which also serves as an engine brace. I'll further want to brace the backrest, since it will get lots of pressure from pushing the pedals using leg muscles. I can make the backrest angle adjustable via the top section. I'll probable mount the backrest with the wider portion at the bottom (pic3) after mocking it up both ways. I'm still hunting a rear triangle from a donor bike preferably a road bike or an mtb. The bike store I usually find them at had none today.
Here are the pics
-Lowracer-

lowracer · Nov 4, 2013

I have been having a time trying to find a suitable donor bike. Frustration got me thinking outside the box again (hate when that happens) on how to get around the donor bike dilemma? I could attach another rigid fork I got laying around to the suspension fork (already been spread a bit to accomodate a wider hub). Then use a 31.8 steerer stem to clamp a bottom bracket. The brake posts on both forks could be used to mount 2 pieces of angle iron and then both forks connected via those angle irons. I went as far as getting it mostly mounted and aligned when I realized that a rear section of a mtb would sure be alot better...lol
So I took it all apart again and am back looking for a salvage bike.
-Lowracer-

bowljoman · Nov 5, 2013

I found putting your feet on the front axle provides such stability that you can let go of the grips at any speed.

This rig went 42 mph. 52CC scooter motor with nexus 3-speed trike IGH jack-shaft.

I went from the scooter motor, through a 5-to-1 pocket bike tranny, then to the nexus, and then to the rear sprocket.

lowracer · Nov 6, 2013

Bowljoman,
Nice...
That front tire is crrrazy.
I ended up selling my 1st gas powered scooter project today.
The Razor with the 32cc Tanaka w/ 10x4" wheels/tires.
I built it for my daughter and she rode it a bunch until her brother crashed his and that was all it took for her to hang up her scooter.
Now I'm down to just this one scooter in my thread here.
I turned the dual Mitsubishi engine full suspension scooter back into a motorized bike w/shift kit.
Still hunting a throw away bike...no luck today fishing for one & I'm not buying one...
Cheers,
-Low-

lowracer · Nov 11, 2013

Same buddy I ended selling my Razor electric to gas conversion scooter wants this one too. This guy and his friends are really having tons of fun on the Razor and want a few to ride together instead of taking turns...I got it loaded up in the trunk and will probably have it sold today. I'm also bringing my Tanaka TC-47 just in case he wants that engine more than the Mitsubishi TU-43 which is on the scooter currently. The MBB recumbent conversion project will be put on hold indefinitely. Too bad the donor bike was difficult to find or I would have finished this.
-Low-

lowracer · Nov 11, 2013

Ok, The scooter is sold & gone.
Murphy's Law in full effect today...I end up getting 2 free donor bikes not 2 hours later today & one of them is a pristine Diamond back 700c hybrid, the other an aluminum URT full suspension MTB (cheapy), but both in great condition.
I cleaned & tuned up the hybrid for my wife (its like brand new) & I'm in the process of 'Scooterizing' the MTB but with my DAX friction driver (not going to have to buy anything). Lets see how long this one lasts before one of my business associates just has to have it for themselves...lol
By getting a bike for my wife, I can re-claim my Litespeed titanium MTB which was converted for her to ride the bike paths...
One more donor & I can turn this scooter MTB into a front drive recumbent with rear engine.
-lowracer-

lowracer · Nov 11, 2013

Oh yeah, here are the pics of both bikes I acquired today for free.
Might have to start a new thread one of these days.
-Low-

Intrepid Wheelwoman · Nov 20, 2013

Free bikes are always good

Scooterising the MTB looks interesting, should make a great project.

lowracer · Nov 21, 2013

I got 2 more free bikes so the materials are all there to begin cutting & building.
One is a Specialized Hardrock XC Disc aluminum frame, & the other a GT 700c Chromoly frame. I'll probably use the GT for the main frame, & the Specialized for the MBB front wheel drive (cutting it up)...
Maybe this weekend if the weather turns bad I'll spend time in the garage working on it, otherwise I'll be out cycling (pedal only) in the nice weather.
Decisions...Decisions
-Lowracer-

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