LWB mountain bike

C

Conrad_K

[rambling text follows]

I bike primarily for exercise. I'm not in a very bicycle-friendly area as far as riding on the street, but there are maybe a hundred miles of paved bicycle or dual-use trails within 30 miles. There might be twice that in "BMX" and "mountain bike" trails within 60 miles.

I have a Re-Bike compact LWB bicycle and a KMX Typhoon trike to take care of paved areas. I could use the Re-Bike on easy trails, but it's a bit small for me; my knees hit the handlebars if I pedal when turning. The 16" front wheel looks a bit small for off-road, and frankly, even though it's pretty heavy, the design is a bit flimsy. It's a very nice 30-year-old bike that's perfectly adequate for paved surfaces, and I don't see any reason to beat it to death off-road.

A conventional diamond-frame mountain bike isn't really an option due to some medical issues. And I think I have the "recumbent bug" anyway. So I've been looking at recumbent designs. Recumbents and off-roading are not a marriage made in heaven, but I found some companies that were selling various recumbent designs set up as "mountain bikes." Some even sold LWBs, which is what I'm primarily interested in. They did acknowledge there could be various issues with LWBs on tight trails, including having to pick it up to make it over logs or around very tight corners.

The local woods trails are all state or city owned, open to the public, and about half of the listings say something like "suitable for children or disabled." That is, not "X-Treem! jumper/stunter/BMX bro" stuff. Probably not impassable to an LWB recumbent.

So, after looking at a bunch of stuff, I decided to go for an LWB. I have a fairly well equipped metalworking shop and an account at a local steel supplier. Atomic Zombie had some designs that looked practical and sturdy; bicycle stuff is new to me, and using a known-good design might be a good idea. Brad took the old site down literally the day I was going to order some plans, so I've been collecting pieces while he's doing all the scut-work it takes to get this new one fully operational.

I found two 20" single-speed kid's bikes leaning against a dumpster, and today I bought a 26", 18-speed mountain bike to strip for chainset bits, brakes, rear wheel, etc.
 
So, what the Voices in my head have come up with so far:

Long wheelbase recumbent

26" rear, 20" front
- my Re-Bike has a 20" rear wheel and the derailleur hangs very close to the ground. Looking at bikes in the store, that seems normal. I didn't want to whack the derailleur on a rock or something, so went for the extra three inches of clearance with a 26" wheel

V-brakes.
- I'd prefer discs, but all my donor bikes are V-brake

10 or more speed chainset

seat height 14 to 18 inches (To Be Determined)

square tube frame
- easier to build than round tube

crankset clamps to frame tube for adjustment
- just in case someone else wants to ride it

front suspension.
- the 26" donor bike has a sprung fork; if one of the 20" wheels I have will fit, I might run that. If not, I'll just use the forks from one of the 20" donor bikes. I'm not sure a front suspension is greatly important for an LWB

rear suspension.
(To Be Determined)

seat.
- I like the upholstered seat on the Re-Bike, but as we move into summer it might get sweaty. The tentative plan is to build a standard "lawn chair" web seat.

steering.
- what I've been looking at is "tank steering." It's USS, with levers that tilt from bottom pivots instead of swinging around a circle. Theoretically tank steering would give me better leg clearance, and that wouldn't change when turning. Downside: handlebar pivots, bellcrank pivot, and four more rod ends, each with its necessary required clearance.

steering angle.
- just replicate whatever the donor bike used.
 
The trails you expect to ride - do you expect to ride the bike to and from them or will you be trasporting your bike there. A lwb anything is awkward to transport for many of us.
 
I plan to extend my old motorcycle trailer as needed. Since I don't have a motorcycle any more, it has mostly been something else cluttering the yard.

The only real problem is where to put it when I'm not riding it. I'll burn that bridge when I get to it.
 
Brad got the plans back up, now all of them for $30. What fresh hell is this? It took several attempts to complete the transaction, as Paypal (which I haven't used in a long time) now wants to text an "authentication code" to the phone number I used when setting up the account. Which is a land line, and doesn't do texts. Nor do I have a cellphone. It seems the whole world is configuring itself to spamming phones with text messages nowadays.

After three attempts it let me in with my password and said the transaction went through, so hopefully I'll be downloading plans as soon as Brad gets around to whatever it he does down in the basement of the forum.
 
I would think a slightly modified tourmaster would be closest to your requirements. Keep std mountain bike front and rear suspension and keep regular handlebars rather than uss or tank as that will likely afford you better control over uneven surfaces. The bigger front wheel will also help.
 
So far, the Tourmaster is the closest to what I want. I'm looking at all the plans now, whether they're anything I'm interested in or not. There are useful ideas scattered all through there.
 
Thanks, Q! I'd already found that page; it was what led me to think it might not be completely crazy to take an LWB off-road.
 
I found out they make wider seats for bicycles. I ordered one that's 10.2" wide instead of the 4.75" side one that came with the parts bike. If my butt will tolerate it, I'll probably put off the LWB conversion until next winter and ride the bike as-is for now.
 
Those wide seats for std bikes often do away with the saddle nose. That removes some of the control over the bike with thigh pressure against the nose being lost. It may still be more control than a recumbent but is something to bear in mind.
 
The seat finally arrived and I got it installed this morning. It has an average-looking nose. I fiddled around with the seat angle and height. To get proper leg extension, the seat is at "hop up and pedal" height. I guess I had entirely forgotten that in the years since I last rode an upright bicycle. My CLWB street bike, I just sit down and pedal.

Brake adjustment, air in the tires, tightening various bits, ready to ride... and by then it was raining. All day. Just sitting on the seat, it's reasonably comfortable, as opposed to the instant pain from the narrow seat it came with.

I'll get a test ride sometime in the next few days, I hope.
 
I got the mountain bike out this morning and took it around the block. The new seat is fine. Unfortunately, by the time I get the seat high enough to get my legs at a decent angle, it's so high I can't safely mount the bicycle. [some mobility problems] Setting the seat down low enough to climb aboard made my knees hurt enough to cut the ride short after riding around the block.

Well, all I'm out is a cheap seat. Back to Plan A, and cutting the bike up for parts.
 
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