Author Topic: Recumbent trike (hopefully folding)  (Read 4499 times)

iddu

  • Are we there yet?
Re: Recumbent trike (hopefully folding)
« Reply #25 on: August 25, 2016, 10:33:09 pm »
>Does anyone have bright ideas about how to make this less vulnerable

Ditch the mech.

Two flat bars, arranged in a V.  Point to RHS (facing seat rear).  Top 'arm' fixed parallel to main tube at wanted drop.  Jockey wheel/hinge at point, Jockey wheel on lower 'arm' tip.  Spring compressing open end.  Should gain at least cage length additional height...you might have to guide return above steering control rod as well, depending on height wanted.

I'd offer you some moral support - but I have questionable morals.

Re: Recumbent trike (hopefully folding)
« Reply #26 on: August 25, 2016, 10:51:20 pm »
>Does anyone have bright ideas about how to make this less vulnerable

Ditch the mech.

Two flat bars, arranged in a V.  Point to RHS (facing seat rear).  Top 'arm' fixed parallel to main tube at wanted drop.  Jockey wheel/hinge at point, Jockey wheel on lower 'arm' tip.  Spring compressing open end.  Should gain at least cage length additional height...you might have to guide return above steering control rod as well, depending on height wanted.
That sounds interesting. I'm having trouble visualising - is it essentially the sprung bit of the derailleur? It needs to be able to take enough chain to make the 52, 42 and 30 tooth chainrings usable. At least until I've sorted out the electric propulsion part and I no longer need the smaller chainrings (might take a while, given that I've been working on this for 20 months so far)! :)
Cheers
Duncan

iddu

  • Are we there yet?
Re: Recumbent trike (hopefully folding)
« Reply #27 on: August 25, 2016, 11:43:04 pm »
A DIY verison of clicky
I'd offer you some moral support - but I have questionable morals.

Re: Recumbent trike (hopefully folding)
« Reply #28 on: August 26, 2016, 09:05:51 am »
Ah. That picture explains a lot.  I always wondered how trikes with an adjustable boom dealt with the excess chain - now I know. :)
I guess the ideal scenario would be to have that setup where the top wheel is fixed and the bottom one is sprung such that it moves directly back away from the top wheel but parallel to the ground. I'm not sure if I can rig that with a spring and a slot - I might be better off just using a sprung derailleur arm (or regular singlespeed chain tensioner) with a pivot point significantly forward of (and higher than) the top wheel.
Thanks iddu - I'll definitely try that solution once the trike is back up and functional.  :thumbsup:
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #29 on: August 26, 2016, 10:04:30 am »
Could the mecb be mounted aa lot further fwd, so that it's nearly between the front wheels? Witb only slack from shifting chainrings to worry about, you coul also use a much shorter cage mech.

Or how about mounting the mech back-to-front so that if it is clonked is just deflects, similar to a Pinion chain tensioner.
Life is too important to be taken seriously.

iddu

  • Are we there yet?
Re: Recumbent trike (hopefully folding)
« Reply #30 on: August 26, 2016, 10:06:48 am »
>I guess the ideal scenario...

Actually yes, that would be better;  Get some appropriate sized open channel (so jockey bolts get support both sides), offset the jockeys slightly in horizontal plane, slot one ends mounting, and have two (external) springs putting slotted jockey under tension.

Might need to slice out additional entry (or exit) space, depending on how you orient the channel/level of offset/resultant wrapped chainline.

That would really flatten line / raise chain.
I'd offer you some moral support - but I have questionable morals.

Re: Recumbent trike (hopefully folding)
« Reply #31 on: August 26, 2016, 01:05:21 pm »
The channel idea is a really good one - should allow consistent chain tensioning, taking up a minimal amount of vertical space, and hopefully be pretty straightforward to assemble.  It doesn't need to slide very often (only when I change chainrings), so maybe I can get away with alloy as well. Now I need to find some to experiment with. :)

Progress on the physical (as well as the conceptual) side as well. I attacked the badly welded BB clamp with a BFH and a crowbar and pulled it apart! That gave me this piece:
IMG_20160826_114842 by duncancmartin, on Flickr
Better pic:
IMG_20160826_114849 by duncancmartin, on Flickr
and this piece:
IMG_20160826_114834 by duncancmartin, on Flickr
Clearly there was very little penetration into the BB shell.
So I cleaned both sides up with a flap disk until they were shiny, replaced the conductive tip on my welder, bolted them to a spare bit of box section (with an extra 1mm sheet in one side for spacing) using the bolts that should hold it to the main boom and some extra clamps, turned the selder up a notch so it was running hot, and then tried again. The result:
IMG_20160826_123423 by duncancmartin, on Flickr
IMG_20160826_123433 by duncancmartin, on Flickr
I went over the welds on the other side because I felt I ground too much off last time, meaning it looks like this now:
IMG_20160826_123413 by duncancmartin, on Flickr

The extra heat meant that the BB was glowing red all the way through to the inside of the shell - the threads seem to have survived OK (I'll chase them with the tool to be certain), so the only downside appears to have been that I kept setting fire to the grease in them!
Once the thread is chased properly then I can re-install the BB and get going again.

Cheers
Duncan

PS the (super shaky) video appears to have uploaded too :) :
VID_20160823_162700 by duncancmartin, on Flickr

Re: Recumbent trike (hopefully folding)
« Reply #32 on: August 26, 2016, 01:32:08 pm »
New idea for how to manage the sliding bit (I would fix the top pulley wheel independently):
Attach these to the inside of some suitably sized box/channel section steel, attach a pulley wheel to one end, and the spring on the other end.  Smooth rolling and (relatively) self contained.
http://www.ebay.co.uk/itm/17mm-280mm-Drawer-Runners-Grooved-Ball-Bearing-Metal-Draw-Slides-/390932002649?var=&hash=item5b055cf759:m:m0ZUjbq0MIc1uRCtTUVw3Eg
Does that make sense?
Cheers
Duncan

iddu

  • Are we there yet?
Re: Recumbent trike (hopefully folding)
« Reply #33 on: August 26, 2016, 02:08:41 pm »
Outstanding bodge piece of design ;D
I'd offer you some moral support - but I have questionable morals.

Re: Recumbent trike (hopefully folding)
« Reply #34 on: September 12, 2016, 09:45:34 pm »
I spaced the inner ring inward with a couple of washers per bolt, which means I can use the middle ring for the back chain.  That reduced my gearing considerably (I think the theoretical top was 136", and now it's 103"!). And I worked out what was causing the front wheel to lock up - it wasn't the brakes binding, but one of the bolts holding the rotor on had come loose! The head was totally mangled, but I managed to remove it, so I got to ride it up and down the street a bit more - the gearing reduction makes it a lot easier!
Unfortunately, the derailleur is still problematic, and it's not going to be as easy as I'd hoped to fit a sliding tensioner. I think this picture illustrates the current setup best (though the front chain is running on the inner ring now, so my issue is slightly worse!):
IMG_20160820_120008 by duncancmartin, on Flickr
To get a nice sliding mechanism in place, what I'd want to do is fit the fixed front jockey wheel around about where the base of the seat is, and then that would give me a foot or 2 of space behind and under it to have the sliding pulley and the mechanism needed. Unfortunately, that's exactly where the tensioned part of the chain runs. I could reduce the deflection in the tensioned part of the chain by using a smaller diameter pulley wheel, or by putting the existing one on the top of the boom instead of the bottom (I'd rather not do that as it's pretty solidly welded on). But while that would make life a bit simpler, it wouldn't solve the problem. It might be part of the solution, together with some extra sheet on the side to allow me to mount everything below the tensioned chainline. I don't think it's properly ridable until I create a solution though. :(
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #35 on: September 13, 2016, 08:11:03 pm »
Maybe I can just get away with a fixed jockey wheel together with this:
http://www.planetx.co.uk/i/q/FSOOSSD/on-one-doofer-singlespeed-chain-tensioner
Would make life easier. Cheap too...
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #36 on: September 16, 2016, 10:06:16 pm »
Well that was an unmitigated disaster.  >:( :'(
I got my new tensioner today. It's pretty sturdy, but it's surprisingly (to me at least) small! Here's a (rubbish, sorry) picture:
2016-09-16_09-24-45 by duncancmartin, on Flickr
It's about as long as the arm on my junk derailleur. So I tried to work out how to attach it in the right place, shortened the chain, and generally realised that I can't use it on the mounting point very easily, and I need another one (or a fixed jockey wheel) to make the tensioning work.

Then I tried to put a second roller on my existing mounting side by side so I could change the route of the return part of the chain. The central part of it wouldn't slot on properly, so I hit it a few times with a hammer to push it on. Then I realised that the bolt had moved in the tube, I hit the bolt, at which point my welds failed. :( This was another weld I made when the tip on my welder was not working properly - I will have to check back and make sure there aren't any others (I think I've broken the only 2!).
2016-09-16_09-24-56 by duncancmartin, on Flickr

Right now I feel like recycling it!  >:(

So, I have 3 options (some with sub-options):
1. Carry on with my current jackshaft design and work out how to fix the chain tension issue.
2. Change over to a different jackshaft design that uses a freewheel/cassette and so has a mounting point for a derailler for this chain - this means abandoning the theoretical ability to attach a motor to the left hand side of the jackshaft.
3. Give up on jackshafts. Weld the roller bolt back onto the frame, ditch the jackshafts and just run the chain front to back.
3a. Leave the rear wheel alone - this will give me really low gears (when I eventually sort out the front mech to shift chainrings) - something like 21 inches to 71 inches with the current rear wheel.
3b Get a new screw on freewheel (11-28 would give 21" to 90"). Also needs a new shifter as my current one only has 6 gears in index mode.
3c Build a new rear wheel on a decent hub meaning I can get whatever gear ratios I want. Means I need a new hub, spokes, rim (can probably re-use one I have) cassette, shifter and maybe derailleur.

I've got stuff I need to do this weekend, so I probably won't have much time to work on it. Will consider my options. I'm kinda fed up of it now, I want to ride it (and start on my next build - a Spirit mid-racer recumbent).
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #37 on: September 25, 2016, 06:49:40 pm »
I decided to use just the one chain, and run it  from the cranks, under the pulley, over the jackshaft, round the wheel, though the rear mech and then back to the front (maybe through a chain tube).  So I did this:

Progress today.
I cleaned up the bolt for the pivot and welded it back on.  Left the welder at setting 6 - lots of heat. Much better penetration - this is after I ground off a few bits of splatter:
IMG_20160925_155455 by duncancmartin, on Flickr

IMG_20160925_155507 by duncancmartin, on Flickr

While I waited for it all to cool down I stripped the old chain off and extended the new one so it goes all the way from front to back.  Then, when the bolt was sufficiently cool, I put the pulley back on, bolted it up and went for a ride up and down the road. :) It basically just works now. :) This is the current chainline situation:
IMG_20160925_162428 by duncancmartin, on Flickr

I need to sort out the bottom bracket, because it's slightly twisted, and once that's done I can look into sorting out a front mech (I can shift gears by hand until then) and some tubing to deal with the return chain. Other than that, it's the riding it and tidying up.  Speaking of which:
1. I got a mirror from eBay and it's not very much use - it's quite small and a long way away, so it's not exactly helpful - what do people on here use (I assume you use mirrors - it doesn't feel very safe without them) and how do you mount them?
2. How does one mount the flag on the back?  Again - eBay flag, sees quite well made, but isn't obvious how you are supposed to put it on:
IMG_20160925_162649 by duncancmartin, on Flickr
3. Where does one cut the axle off? This is what it looks like now, and it catches on stuff when I put it in and out of the garage:
IMG_20160925_165811 by duncancmartin, on Flickr


Progress on prepping for the next project (I want to build a Spirit recumbent bike - looks a bit like an HP Velotechnic) - I chopped the old crank off the donor rear triangle - had to cut 2 separate slots in it as even after I had chopped a quarter of the crank off it still wouldn't budge!:
IMG_20160925_164345 by duncancmartin, on Flickr

I was then able to get the BB out, and then I chopped the back triangle off the main frame:
IMG_20160925_165959 by duncancmartin, on Flickr
It's kinda hard to undo the bolts though - I might end up having to drill it out. :(
I'll create a new thread for that at some point when I do more than chop old bikes up! :)

Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #38 on: October 02, 2016, 06:14:56 pm »
One step forwards, one back....
I tack welded along the edges of the clamping plates so that when they were done up the chainset is now parallel with the main boom. :)
I then discovered that the front mech isn't going to work, because the seat tube of the bike I chopped up is curved - the lower portion is at the correct angle, but the top portion leans back too much. I guess I'm going to have to chop the tube halfway down and fit a straight one over the top so it goes high enough at the correct angle...
Planning on chopping the axle stubs this evening and trying to ride it up and down the street again. I also need to adjust the mirror location, because it's a bit far way, meaning it's hard to get a picture of what's actually behind you...
While it would be nice to get the front mech working, it's not actually vital to riding it - I can always change gear using my hand! So long as today's modification works, it feels a little like it's basically usable, and everything left now is fine tuning and adding nice to have features like mudguards/lights/mirrors/chaintube/proper seat covering/folding etc. That is a lot of things to add before it's "finished", but they shouldn't stop me geting on and trying it out. Hell, maybe I'll want to add under seat steering!
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #39 on: November 28, 2016, 01:02:24 pm »
 Too late for this build but re the bb shell, in Holland you can get (off the peg) bb fittings designed to slide on and clamp on 40mm box section (alignment square to your tube guaranteed). They say it's for 40mm alu box but I don't see why it shouldn't work for steel as well. I'll sort out the link if anyone is interested. Not the cheapest of solutions but might be worth having strong and hasslefree bb fitting.

Re: Recumbent trike (hopefully folding)
« Reply #40 on: November 28, 2016, 08:09:15 pm »
The link would be nice - I'm thinking of building a 2 wheel recumbent when this one is finally done! ;)
Cheers
Duncan

Re: Recumbent trike (hopefully folding)
« Reply #41 on: May 18, 2017, 09:05:28 am »
Too late for this build but re the bb shell, in Holland you can get (off the peg) bb fittings designed to slide on and clamp on 40mm box section (alignment square to your tube guaranteed). They say it's for 40mm alu box but I don't see why it shouldn't work for steel as well. I'll sort out the link if anyone is interested. Not the cheapest of solutions but might be worth having strong and hasslefree bb fitting.
Hi mzjo - do you have this link?

I made some progress on this project a couple of weeks ago - cut the tube for the front mech - made a moon shaped spacer out of 1mm steel, welded it into the gap and fitted the mech.  I also dismantled an old rear mech, so now I have a little bracket to weld onto said tube to act as a cable stop. Waiting on another thumb shifter (will have to pop down to the Broken Spoke this weekend to get one) - I think I have sufficient outer and inner cable to do the rest of it now.  The same weekend friends came around to borrow the welder to make a tall bike - they all had to have a go on the trike! :)

Once the front mech is sorted, it will be time to ride the thing around the place a bit and sort out the headsets properly. :)

Re: Recumbent trike (hopefully folding)
« Reply #42 on: May 18, 2017, 09:54:24 pm »
Congratulations on the build. That's a fine effort for a first offering.
Mild steel can obviously get very heavy but it's very forgiving and really good to MIG. It used to amaze me how much weight is added after welding [might have something to do with how much stuff I was putting down there]. And of course all sorts of scrap bikes are lying about the place ready to have their bits chopped off to be adapted elsewhere!

it will be time to ride the thing around the place a bit and sort out the headsets properly. :)

It's satisfying to build a bike, and equally satisfying to put some miles on it to show that it's a worthy machine and actually rides well. Putting through it's paces also tends to bring forth all kinds of weaknesses and issues that weren't apparent as it's sitting in the garage. But that's all part of the fun. Then more ideas comes and you go onto the next build. And then the next.

Garry Broad

Re: Recumbent trike (hopefully folding)
« Reply #43 on: May 19, 2017, 02:20:30 pm »
Congratulations on the build. That's a fine effort for a first offering.
Mild steel can obviously get very heavy but it's very forgiving and really good to MIG. It used to amaze me how much weight is added after welding [might have something to do with how much stuff I was putting down there]. And of course all sorts of scrap bikes are lying about the place ready to have their bits chopped off to be adapted elsewhere!
Thanks. :)
I'm already wondering about whether I can teach myself to TIG using my current machine (I have a scratch start inverter box with a few tiny gas bottles), or whether I should go out and buy something that will require less skill to start! That would mean I could weld thinner more bike suitable tubes!
It's satisfying to build a bike, and equally satisfying to put some miles on it to show that it's a worthy machine and actually rides well. Putting through it's paces also tends to bring forth all kinds of weaknesses and issues that weren't apparent as it's sitting in the garage. But that's all part of the fun. Then more ideas comes and you go onto the next build. And then the next.
I've not yet got to the satisfying riding bit, but I already have some more steel tube, a chopped up MTB, and a kids BMX sitting in my garage waiting to turn into a SWB 2 wheeled recumbent. A head-tube and a back wheel and I'll have enough bits to get started! Must finish the trike first! :)

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Recumbent trike (hopefully folding)
« Reply #44 on: May 20, 2017, 12:15:35 am »
It's more than a decade since I built a recumbent. Maybe it's about time to build another...
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.