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Prototypes Under construction Monostay No real purpose to this trike other than just to see if the monostay using 1" x .064" wall square steel will be strong enough to withstand the twisting action of the chainstays being both on the same side. If it doesn't work for an adult, then a child will be able to ride it. At the very least, it will be a learning exercise. Click the pictures for bigger images.
Side view. 20" rims all around with 14mm axles. A 20" rear should hopefully reduce the torque on the chain stay. The frame is essentially the same as the MK 3 but with a shorter, and lower angled set of chain stays.
Might need to add another cross member just in front of the chain roller to reduce/eliminate main frame rail flex. Seat back suport would be added to the top rail just in front of the rear wheel.
I think the left side view makes the wheel look pretty clean :)
Final shot with 6 speed cluster on the hub. Recumbent I'd really like to try my hand at building a recumbent as well and thought I'd mock one up.
It's a 20/26 frame with 2" backbone and a 3/4" x 1/16" swing arm. I figured the same one off the trike could be used but the pivot bolt could likely be downsized as it won't get near as much lateral torque on it as on a trike. One I get a chance to pound hard on a 1½" boom on the trikes, I'll know if I can reduce the sixe of the main boom to 1½" as well. My main concerns were heel - wheel clearance which is why the boom is so long. I will likely make it an OSS and will likely straighten out the chain line a whole lot. After riding the trikes, it's no big deal to maneuver the bike/trike by hand to make a really tight turn, which might be a problem if I lowered the chains so they ran more beside the front wheel. A friend of mine is a lighter rider and already a good spinner. One of his concerns is weight. I thought I'd design a trike that sort of merges the twin rail and flying cross and use a 1¼" x 1/16" wall steel backbone with 1" mild steel crossmembers and chain stays. I wanted to lighten it a bit and see how much the boom flexes, if any.
The frame design is a cross between the first two flying crosses I built. I tried to make the frame as straight as possible to minimize cutting and to simplify the chain line. The rider is shorter than I normally build for so I wanted to move the wheels ahead, open up the cockpit, but still maintain heel - crossmember clearance. I think I solved this by angling the crossmembers forward by 22½" degrees while still maintaining the 15 degrees of caster and camber.
Additionally, to try to stiffen up the rear end, I triangulated along the tail of the backbone. I'll find out if this works once it's built. The trike was designed around the 20/26 wheel sets. The main frame could likely be shortened by an inch or two, but the extra length allows maximum seat angle should it be required. While it might be extra weight, thesteering/brake arms are reduced to 3/4" from 1" as I feel they could be downsized as well. The specs should be as follows:
My brother is a big guy (6' 4") and works in an office with limited bike parking space outside, not to mention security issues. His commute is fairly short, but the center of the trip to work goes through a "bowl" with some pretty steep hills on both sides. I wanted to make a trike that was short, low, had a narrow track, was easy to pedal up steep hills with and was hopefully small enough to take into his cubicle and go under his desk.
Nothing too spectacular - the same basic design and materials as with some of my other trikes. It's just dropped down closer to the deck and shortened up due to the 16" wheels. The trike is modelled with a 62/52/38 crankset but I'll likely put a standard 48/38/28 on it. He's not a real speed freak and he'll be able to go plenty fast enough coasting down the hills anyway.
It's pictured set up for rim brakes but I have some disc mountain bike hubs I've machined to take 12mm bearings so I can lace those into the 16" rims as well and hook him up with front disk brakes. I have Kenda Kwest 16" x 1.5" rubber for the front so standard road calipers will fit around them if I decide to stick with rim brakes. I'll use twist shifters instead of bar cons and use sintered bushings in the king pins with grease nipples.
The 16" rear wheel poses the problem of the bottom derailleur pulley being close to the ground. To try to lessen this problem, with the 16" wheel, I'm going to use a 11-28 cluster as that will produce a 16 gear inch low gear which should be more than enough for the hills. Additionally, a short cage derailleur can be used and that might give a little more clearance with the ground. If it proves problematic, I can always go to a 20" rear wheel with an 11-34 cluster and still get about 16.5 gear inches plus more top end. With more than a foot lopped off the frame, it should be into the high 30 lb range as well. The specs should be as follows:
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