Legs Larry's Glossary of 
Unorthodox Bicycle Jargon

Bike Layouts
LWB Long wheelbase. The front wheel is ahead of the pedals.
SWB Short wheelbase. The front wheel is behind the pedals.
CLWB Compact long wheelbase. Slightly daft (IMHO) term for MWB (see below).
MWB Medium wheelbase. Pedals are mounted more or less above the front wheel
Note 1: Some have attempted to define layouts in terms of actual numbers. This has several disadvantages:
  • You have to know what a bike's wheelbase actually is.
  • Most of them quote a number in inches, which is anathema to a sizeable proportion of the world's population.
  • For a bike made in several different frame lengths, the smallest might be an SWB and the largest an MWB. Tell me this makes sense.
Note 2: Some manufacturers will tell you that their machines are MWB, when according to the above definitions they're SWB. I know an SWB bike when I see one, and that includes the Lightning P-38.oops, what a give-away.
Trike Layouts
Tadpole Two front wheels, one rear
Frog One front wheel, two rear
Delta = Frog
Two-Seater Layouts
Tandem Two riders in line
Sociable Two riders side by side
ASS Above-seat steering. Machine has handlebars more or less like an upright (though designs vary tremendously). Need not be physically above the seat, just generally at a greater altitude.
USS Under-seat steering. Handlebars are sort of below or beside the rider. May be connected directly to the fork, or by a linkage. Need not necessarily be under the seat as such.
OSS Alternative version of ASS. Stands for Over-seat steering, means the same.
BSS Alternative to USS (Below-seat steering)
RWS Rear-wheel steering. Found on some trikes. It's difficult (though not impossible) to make it work properly. Occasionally people will think they're onto something by trying to build an RWS bicycle. They usually manage to build it, but riding it defeats them. So I'll just say: 
RWS bikes are a bad idea!!!
FWD Front wheel drive. Often used on racing machines to avoid having to route miles of chain around an inconveniently-placed rider. Also found on utility machines, to keep the chain short. Fixed-boom FWD machines often have rather limited steering lock, while those whereupon the pedals, chain and front wheel move as a unit can be tricky beasts to learn to ride. The former often requires a whole bunch of non-standard bits.
RWD Rear wheel drive. As used by most bikes.
2WD Two wheel drive. Found on some back-to-back tandems - each rider drives one wheel. Avoids messing around with timing chains, which can be prone to falling off, and each rider can pick their preferred gear ratios and cadence.
  With the increasing popularity of fully- or partly-suspended mountain bikes, the boingy bits are getting cheaper. Especially when it is borne in mind that a recumbent doesn't really need four inches of suspension travel at each end (unless it's an Ostrad).

As a general rule of thumb, front suspension is more beneficial on SWB bikes, rear suspension more so on LWB bikes.  Actually, rear suspension is good on all bikes.  And trikes...

Putting suspension on the two-wheeled region of a trike requires a good deal of engineering, ingenuity or both, as does suspending the front wheel of a front-drive bicycle.

Wheel sizes
  Recumbents come with a bewildering variety of wheel and tyre sizes. To make matters worse, there are, in many cases, several different actual diameters referred to by the same "inch" size. Stick to ISO sizes to (try to) avoid confusion. 

http://www.sheldonbrown.com/tire_sizing.html contains more information than most sane people need to know about tyre sizes. As a summary:

16" Most often ISO 305 or ISO 349 - the latter is more prevalent in the UK, due to the popularity of the Brompton folding bike, while the former is more popular elsewhere.
17" ISO 369, used by some Moulton bikes and assorted recumbents.  Awooga!! Rumours of the death of the 369 tyre have been greatly exaggerated - while the Wolber-manufactured Moulton tyre appears to have gone the same way as the collared dove I encountered in the middle of the A1 the other week (guess...), there are now tyres in this size available from Continental and Bridgestone.  The Wolber slick is apparently still available, but at eighty pounds each, they would be...  So do not write off this fine wheel size just yet J
20" Usually ISO 406 - the common BMX size. Sometimes ISO 451, a not-at-all common size. Sometimes something even more perverse.
24" Don't get me started on these.  Can be ISO 507, 520, 540, 541, 547 and probably half a dozen others as yet unknown to science.  540 and 541 are interchangeable.  Which is nice.
26" Usually ISO 559 - the common mountain bike size. Can be one of about five others, but most likely to be ISO 571, as often used by triathletes trying to be different.
27" Usually ISO 630, and heading for extinction. My upright tourer has them. Nuff said.
28" In recumbent terms, this is an infrequently-used Dutch/German alternative for ISO 622 / 700c.  Coz the only other "28 inch" I know off is the ISO 635 used by ancient rod-braked roadsters.  Yes, I know a 700c is smaller than a 27 inch...
700c ISO 622 - common road bike / hybrid size
The use of anything else should not be countenanced, as you can likely only get the tyres in one shop in the Universe. And they've just sold the last one to someone else. Not that it matters, when the shop is in California and you're on tour in Greece. Stick to 406 and 559 and you won't go far wrong.
Other Stuff
Boom That bit of the frame on a SWB machine which sticks out the front with the bottom bracket on it. Many machines have a sliding boom, wherein the bottom bracket may be moved fore and aft to adjust the machine for different length riders.  Nice, but it does mean that you may have to change the length of the chain.  For FWD bikes, "fixed-boom" means that the bottom bracket stays put when the front wheel is steered, while the alternative, "moving boom" perhaps, has the bottom bracket moving in unison with the front wheel. Machines like these can be tricky for the novice rider, as the steering is done (mainly) with the legs. Indeed some models of Flevobike /trike have handlebars which have no steering function whatsoever, merely serving as a convenient place to mount brake and gear levers.
Pedal steer A phenomenon only noticeable on machines which place the pedals significantly ahead of the steered wheel(s). When pushing on the pedals, the front of the machine rocks gently from side to side. Not a problem really, though some pundits scream and shout about it...
Recumbent butt Muscular aches and pains in the sit-upon caused by over-exertion of unprepared muscles being sat on at the same time. Like cramp, only worse.

Perversely, the condition is usually associated with the more upright variety of seat back, generally found on "comfort"-orientated machines.  The typical reclined racer, which puts more weight on the back and less on the sit-upon, rarely causes this complaint...

S&S S&S couplings are ingenious devices which allow a bicycle frame to be dismantled into smaller parts for transport or storage. See http://www.sandsmachine.com/ for details
IPS IPS = Independent Pedalling System, a system which permits one crew member on a tandem to pedal while the other doesn't

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