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Idiots guide to mtb suspension

bob5820

Chimp
Apr 23, 2006
1
0
Looking for a web page or faq that covers mountain bike suspension. Basically need something that describes how mountain bike suspensions work, and how to set them up. A site that defines what "sag" is or what "pedal platform" means and the differences between all the different technologies such as "DW link" and "Horst link". I realize that some of this may be manufacturer specific, but I'm just looking for a guide to get me started, so I can follow what you are all talking about in the forum, and more importantly so I have a better idea of how to set up and maintain my bike.
 

mud'n'sweat

Falcon
Feb 12, 2006
1,250
0
Don't know of a web page for you, but I can answer a couple of your questions. Sag is the amount of shock compression you get when you are simply sitting on the bike without activating the suspension shock with varying terrain. To measure sag, use a zip tie zipped down to one of the stanchions on your shock to mark high much the fork travels when you are sitting still on the bike.

Pedal platform is an attempt at a cure for a common plight that manufacturers are always trying to battle. This is basically the battle against "pedal bobbing" which is the amount of effeciency loss during pedaling due to the suspension bobbing and compressing from your pedaling force. Pedal platforms are designed to help eliminate the amount of pedal bob one gets when mashing hard on those spinners. :)
 

S.K.C.

Turbo Monkey
Feb 28, 2005
4,096
25
Pa. / North Jersey
Ask and ye shall receive:

SHOCKS & DAMPERS
Noleen Racing and Works Performance, both motorcycle suspension firms, made the first production hydraulic dampers specifically for bicycles. Motorsport suspension companies still dominate the mountain bike shock market, with companies like Fox Racing Shox, and Ohlins (Cane Creek co-designed Double Barrel shocks). Here's what you need to know:

Eye-to-eye length: The distance between the center of the pivot locations on either end of the shock at full extension. This measurement is important when ordering a replacement.

Stroke: The distance that the shock compresses.

Damper: The body of the shock that contains the hydraulic fluid, piston and valving (same as shock body).

Damper shaft: The rod or tube that drives the internal damping piston.

Coil/over spring: The classic configuration that uses a metal coil spring, mounted externally over the shock body.

Airspring: A piston that acts against compressed air or gas to support the rider. Air springs are integrated into the shock body.

Negative spring: A short-travel spring inside the shock body that opposes the main spring to soften the first part of its stroke.

Compensator chamber (Also “separator piston”): a sealed piston that rides between the shock fluid and a chamber filled with compressed gas. As the shock shaft is plunged into the damper, the shock fluid displaces the compensator piston and compresses the gas in the chamber to compensate for the added volume of the shaft.

Piggyback chamber: The same function as a compensator chamber, but it is moved to a remote location to conserve space, or to shorten the shock’s eye-to-eye length.

Preload collar: A ring, threaded onto the shock body that supports one end of the coil spring. Turning the ring increases or decreases the starting spring tension. This adjustment is used to set the ride height (sag) of the rear suspension.

Progressively wound spring: A spring with its coils spaced closer together on one end to create less resistance when it is first compressed.

Blow-off valve: Any type of hydraulic valve designed to resist the flow of fluid until it reaches a predetermined pressure threshold. Usually used to protect a lockout-equipped damper from high-pressure damage.

Lockout: Any type of external hydraulic valve that prevents the shock from being compressed.

Free-bleed circuit: A hole or port that allows shock fluid to bypass the shock’s main damper piston during the compression and rebound cycles.

Low-speed compression clicker: A valve that restricts the free-bleed circuit during the compression stroke.

Low-speed rebound: Functions the same as the compression clicker as the shock is extended.

Sag indicator: Typically an O-ring on the shock shaft that gives a visual indication of how far the shock has been compressed.

Damper piston: A perforated piston attached to the shock shaft that reciprocates through the fluid inside the shock body. One-way valves on either side of the piston meter the flow of fluid to create compression and rebound resistance.

Spring rate: The amount of force that a spring produces when it is compressed one inch. If you placed a 300-pound spring on a bathroom scale and compressed it one inch, the scale would read 300 pounds—compressing it two inches would read 600 pounds.

REAR SUSPENSION TYPES & MONKEY MOTION JARGON
Dual-suspension bicycles represent the most technical aspect of the sport and thus, the least understood.

Four-bar linkage: Refers to systems with three articulating levers:
(1) The swingarm.
(2) The seatstay assembly
(3) And a link that drives the shock. The fourth “bar” is the rear section of the frame between the swingarm and upper pivot locations. (Specialized FSR and Intense M-1).

Mac-Strut (MacPherson Strut) suspension: A conventional swingarm that drives a shock that is rigidly attached to the seat-stay assembly. (Titus and Turner make the best examples.)

Swing link: A link that serves no purpose other than to eliminate lateral stress from the shock assembly. (As on the Fisher Sugar and Jamis Dakar.)

Monoshock: A term stolen from circa ’70 Yamaha motorcycles that refers to a
triangulated swingarm with a single pivot near the bottom bracket. (Santa Cruz Superlight, Foes DH-Mono and Ellsworth Joker.)

Cantilever beam: The simplest design, it uses a large-diameter swingarm with a single pivot near the bottom bracket area (Rocky Mountain RM-7 and K2 Flying Monkey).

Parallel link swingarm pivot: A pair of linkage arms above and below the swingarm that allow it to swing in a different arc than a conventional single-pivot swingarm. (For examples see the Rocky Mountain ETS-X, KHS’s and Karpiel’s downhillers.)

Horst-link: Any rear suspension that uses a conventional swingarm linked to a seatstay assembly that is rigidly attached to the rear dropout. (Specialized FSR, Intense Tracer, Ellsworth Truth.)

Floating drivetrain (URT): When the bottom bracket is mounted to the swingarm instead of the frame. (The Ibis Bow Ti, GT i-Drive and Maverick American are modifications of the concept.)

Active suspension: Any suspension that reacts to bumps without being affected by braking or pedaling inputs. (Intense Uzzi, Specialized FSR, Ellsworth Truth.)
Reactive suspension (Also semi-active): Any design that is affected by braking and pedaling forces. (Giant NRS, Santa Cruz Blur.)

Progressive rate (Rising rate): Any configuration that amplifies the effects of the spring and shock as the suspension reaches full compression.

Falling rate: Opposite of progressive rate suspension.

Straight rate: A suspension system that causes the spring and damping forces to increase in direct proportion to its rate of travel.

Plain bearings (Bushings): The tubular sleeves of metal or plastic that the suspension’s pivot pins rotate within.
Sealed bearings Generally refers to cartridge-type ball bearings equipped with seals. “Cartridge” describes the fact that the balls, races and seals are permanently assembled into a single unit.

Hope this helps...:)
 

sneakysnake

Monkey
Apr 2, 2006
875
1
NC
that pretty well explained everything and more that was asked, except i didn't see dw link mentioned; so here it is. pretty much dw link was designed specifically for iron horse(correct me if i'm wrong), well anyway to the best of my knowledge only iron horse uses the link on their sunday line of bikes and their 7 point line. i could go into all the specifics of how the linkage works and why it is so wonderful, or i could just give you a link that would explain it a lot better than i ever could.

http://www.dw-link.com/home.html
 

S.K.C.

Turbo Monkey
Feb 28, 2005
4,096
25
Pa. / North Jersey
Thanx a lot, it did help..... I really appreciate the time and effort put in to make that. Unless you cut~n~pasted it all!
Hey - no problem. :)

Most of that was from info I've collected over the years. Guess I forgot to add the DW link though... my bad.:o: