2. Parts & Materials - crunchysteve/TriceratopsTwo GitHub Wiki

Frame Parts

Structural steel (or better, eg chromoly if you can get it)...

  • 300mm of 50 x 5.0 Square Hollow Section (SHS),

  • 3000mm of 35 x 1.6 SHS,
  • 450mm of 30 x 1.6 SHS, (long legs? you may need more - for bottom bracket spar)
  • 2000mm of 20 x 1.6 SHS, (assorted brackets and bushes)
  • <500mm of 16 x 1.6 Elliptical Hollow Section, (EHS, aka round tube)
  • <500mm of 35 x 1.6 EHS for handlebar mounts
  • 2x ISO disk brake mounts (I recommend this one https://trisled.com.au/product/disc-brake-mounting-plate/ )
  • Bottom bracket shell (try this one https://trisled.com.au/product/bottom-bracket-shell/ )
  • various bolts, nuts washers (more detail as this document evolves)

Also, depending on whether you build your own rear triangle (design coming) or use the backend of a donor bike (like mine), you will also need tubing to suit. I'll be using 20 x 1.6 SHS in my design, as this allows for some high strength construction techniques, such as vertical diagonal axes (the corners at the top, sides and bottom, rater than the tube laying flat) and angle cut joins to the main frame for more torsional rigidity.

Seat Parts

The seat "design", where shown in the current pictures, is sheets of 9mm marine ply. You may want to get some 1.6mm sheet steel,cut and bend it, to create a racing seat design, then pad or upholster as desired. Or, you could get something like this...

I'm planning to go the home-built, sheet steel option with lots of vent holes... to save weight. I'd recommend rounding all corners and welding some flat-bar around all metal edges. Heavier, but hella sharp edges without.

Groupset Parts

The following parts are the "bicycle" components, such has wheels, bearings, steerer clamps, gears, brakes, handlebars, etc.

  • 2x 20" front wheels - 100mm x 12mm thru axle hubs, 28 or 32 spoke to your preference. (I'm going 28 spoke)
  • 1x 20" rear wheel. - 135mm QR or 135mm or 142mm, 12mm thru axle, 11 or 12 speed hub, 32 spoke recommended.
  • 1x 10, 11 or 12 speed cassette to preference. I cycle tour, so I only really need 24 gear inches to 100 gear inches, which a 1x10, 11-46 cassette gives me nicely. Pick what your desire or budget craves. Also, you could go 2x at the front, or Rohloff at the rear, but remember, long chains on recumbents need more care and can be slacker around smaller drive cogs often found on hub systems. Chain management will be covered in a later chapter.
  • 2x "hydro" disk brake and lever sets (for front)
  • 1x mechanical disk brake (for rear) - the rear is for emergencies and for use as a parking brake
  • Friction bar-end or thumb shift lever for rear brake and long cable set. (Parking brake, remember.)
  • 3x (at least, 4x if you're tall) chains to suit your derailleur and cassette (as well as spare joining pins and a chain tool.)
  • At least 4 large derailleur jockey wheels, 5mm rivnuts and 5mm bolts for chain guide system. (Or 13mm plastic irrigation hose and clamps.)
  • 31.8mm/22mm "flat" handlebar with wide centre. (mountain bike bar) This gets cut in half and each half is mounted in a clamp on the tilt brackets.
  • Bottom bracket and crankset. Because of 20" wheels, you'll need at least a 56 tooth chainring, I know I do. (20" * 56t / 46t = 24 gear inches, 20 * 56t / 11t = 102 gear inches. 10km/h to 44km/h at a cadence of 90RPM)

The parts list will be updated regularly until the design settles. Always be sure you know what you want in your own build and make your own parts lists.

Parts and Materials Notes

Wheels

I'm using 20" wheels all round. Yeah, that's a harsher ride than a 29er or a 27.5/26er on the rear, but I carry one spare tube. One. Especially when touring. I don't want to be carrying 2 parts for one job. If you run tubeless, this is never a problem, choose your wheel sizes with abandon. Obviously, with a lean steer design, taller front wheels will encroach more into the rider space, so 20" is a good compromise, especially as, in Australia, the only rules for trike design are mobility scooter rules, so I figure that, if I'm as narrow as a "gopher truck", which is allowed to use a footpath, and no wider than a slack, downhill mountain bike with a super-wide handlebar, then I'm good. Again, a 406 ETRTO rim is easy to find tires, tubes, tubeless systems, etc for, as well as not encroaching my personal space. If I need more comfort, I can go bulbous, tubeless and low pressure. Something tells me lean steering is not off road rated. Ackerman steering is probably better suited to trails and gnarl. Screw comfort &#128514

Steel

This trike, as I spec it, is heading for little or no "change" out of 20kg with no touring equipment fitted, compared to my 15kg touring bike with Blackburn Outpost cages as front racks and a typical alloy pannier rack at the rear. This is the bare weight of my dutch cargo bike with no load box, and it runs to 30kg with an empty load box so, while not light, it'll have very good coasting momentum and gears always help. The biggest advantage, though, is AERO! Recumbents are low and cheat the wind. I average 15km/h on my "dutchy", loaded or otherwise, even with headwinds, because I spin lower gears at 90RPM, I average 20km/h on my tourer, even laden, in headwinds, for the same reason. The aero advantage of this trike, coupled with a low centre-of-gravity, makes for less wind and rolling resistance than an upright bike. Mass only becomes an issue during acceleration and a little on steeper hills. And the other cool thing about a trike, the aero doesn't lose that much tailwind help. The seat keeps the wind trapped between your back and the ground.

However, weight might be important to you, in which case, you want lighter frame parts. If you go thinner walled, you'll need to also go for aircraft grade chromoly. Again, locally to me (Melbourne, Australia), Trisled have a good selection of chromo. I'm using structural steel because I'm on a retiree's budget and that chromoly from trisled only comes in EHS, and I'm not tooled to build frames with round tubes.

Aluminium

Don't be deceived by aluminium. 6005 aluminium tubing can be easily welded using a MAPP gas torch and alloy "brazing" wire, but it loses temper at the joins when welded (gas or TIG, you can't MIG weld it) and needs some quite complicated heat treatment to get back to hardness. Even if you have affordable access heat treatment facilities (one crowd near me want AU$2000 for a bicycle frame, they wouldn't even quote to heat treat a trike), 6005 alloy will fatigue and fail. Not quickly, but it's a 10 year frame, at best. You will need thicker walls if you can't heat treat, up to 1.5 to 2 times thicker, depending on the load points. Aluminium may not save you any weight.

You could do housing joins, where tubes are tightly inset inside the tube they connect to, but this adds complexity to cuts at joins and won't help as much on joins with large amounts of angular force on them, like the steerer tube or the bottom bracket spar out front. You need to make sure the weld sweats into the housing, too, to increase the surface are of the join, which makes the join loose, creating more reliance on precision jigs. Housing joins can't easily be done for the head tube as there's not a lot of clearance between the outside of the steerer and the inside of the head.

Carbon Fibre

If you know how to do this stuff, and are tooled up for it, go for it. You could use off-the-shelp tube, too, and either cast lugs from aluminium cans, or do a carbon/resin wrap, but you still need to "bake" the joint under controlled conditions for the latter and the former (cast lugs) is fraught, required precise moulds, precise fit and aluminium expands and contracts, while carbon doesn't. One unseasonably hot day, and your glue fails in the lug.

Wood

Don't laugh! Wood is the original carbon fibre, is almost as light and is much easier to work, as well as to interface to metals. If my steel trike works out, I may build a wooden version, just to show off. Many have! Check out the Zelo, built from Poang chair parts. Again, wood does have more challenges than steel and may not save a lot of weight, then again, engineering challenge accepted?

Also, in the world of wood, bicycles are frequently made from bamboo (actually a grass, not a timber, but...) and some have even built tricycles. Want to adapt my design to wood or bamboo? It'll be a challenge, please show me your adventures in a green alternative material! Diversity is fun!