First in a series of posts showing the guts of various "shock" forks usually seen on mountain bikes, comfort bikes and some recumbents.
There is a mix of technologies inside the forks that owners can't see. Price point plays a huge roll in what is in there. A major problem is identifying forks. Most makers kept changing colors, decals and what they put in the forks every year. Few put a date on them. You might read some good/bad reviews and the reviewer is referring to a completely different fork because they don't know the difference in models & years.
The vast majority of shock forks are just a coil spring in each leg with a rubber pad to cut down on the slam when you bottom them out. Any dampening effect is just the stiction of the plastic guides between the upper and lower fork bades. Rubber boots that dissolve in sunlight letting dirt, grit and water in to the sliders. The older a fork gets, the more stiction until it finally seizes up. Most are on bikes with the warning sticker "not intended for off road use or stunt riding". You can often hear the springs slapping on the insides of the fork tubes when hitting bumps. Welded construction is a sure sign of cheap junk. Turns out welded shock forks are one of the most recalled bike products. So much so the Asian bike industry puts exact dates of manufacture on bikes so when a recall is issued, it only applies ot a week or two of production, not every model ever made. Hum, like FDA recalls for contaminated meats.
The next step up is elastomers. A stack of plasticy rubbery pads inside the tubes. Those elastomers don't usually last very long. The chemistry of the various plastics isn't stable over time. I've seen them melted in to a nasty puddle of goo that only gasoline can remove, dissolved into a pile of dry dust or petrified to rock hard. Some makers offered replacement pads with different compression rates, each in a different color with a different life span. Most have limited or no adjust ability. The metal parts are often pressed in to place, not welded, and not anything you can dismantle without destroying.
The more costly high end forks will have air compression and oil dampening. Usually 1 fork blade has the "spring" and the other has the "shock". Fine tuning of each is done via air pressure, different shock oil SAE weights or adjustable valves. Some will be equipped with remote lockouts, useful for pedaling hard up hill to reduce pogo effect that sucks up your energy. Many have the upper fork tubes bolted in place.
All types usually need some maintenance. Most don't have replacement parts available. Tools needed can vary quite a bit.
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Today's fork is a Manitou Spyder. Exact age unknown. Probably 20 to 25 years old now. Elastomer & metal springs with adjusters. Single cast crown, not welded. Same gear in each fork blade with separate adjusters that should be dialed equally. On this particular fork one of the knobs is missing but the adjuster shaft is still turnable. Decent rubber boots that had slipped off the lower fork and were full of sludge. The elastomers have held up well. Plenty of grease in there so nothing wore out. This fork as a pair of tiny ports for injecting more grease. Overall a good long lasting budget fork but with limited ability. Disassembly only requires a 1" 6-point socket. Good for a beater bike not up to single track duties or racing.
There is a mix of technologies inside the forks that owners can't see. Price point plays a huge roll in what is in there. A major problem is identifying forks. Most makers kept changing colors, decals and what they put in the forks every year. Few put a date on them. You might read some good/bad reviews and the reviewer is referring to a completely different fork because they don't know the difference in models & years.
The vast majority of shock forks are just a coil spring in each leg with a rubber pad to cut down on the slam when you bottom them out. Any dampening effect is just the stiction of the plastic guides between the upper and lower fork bades. Rubber boots that dissolve in sunlight letting dirt, grit and water in to the sliders. The older a fork gets, the more stiction until it finally seizes up. Most are on bikes with the warning sticker "not intended for off road use or stunt riding". You can often hear the springs slapping on the insides of the fork tubes when hitting bumps. Welded construction is a sure sign of cheap junk. Turns out welded shock forks are one of the most recalled bike products. So much so the Asian bike industry puts exact dates of manufacture on bikes so when a recall is issued, it only applies ot a week or two of production, not every model ever made. Hum, like FDA recalls for contaminated meats.
The next step up is elastomers. A stack of plasticy rubbery pads inside the tubes. Those elastomers don't usually last very long. The chemistry of the various plastics isn't stable over time. I've seen them melted in to a nasty puddle of goo that only gasoline can remove, dissolved into a pile of dry dust or petrified to rock hard. Some makers offered replacement pads with different compression rates, each in a different color with a different life span. Most have limited or no adjust ability. The metal parts are often pressed in to place, not welded, and not anything you can dismantle without destroying.
The more costly high end forks will have air compression and oil dampening. Usually 1 fork blade has the "spring" and the other has the "shock". Fine tuning of each is done via air pressure, different shock oil SAE weights or adjustable valves. Some will be equipped with remote lockouts, useful for pedaling hard up hill to reduce pogo effect that sucks up your energy. Many have the upper fork tubes bolted in place.
All types usually need some maintenance. Most don't have replacement parts available. Tools needed can vary quite a bit.
---
Today's fork is a Manitou Spyder. Exact age unknown. Probably 20 to 25 years old now. Elastomer & metal springs with adjusters. Single cast crown, not welded. Same gear in each fork blade with separate adjusters that should be dialed equally. On this particular fork one of the knobs is missing but the adjuster shaft is still turnable. Decent rubber boots that had slipped off the lower fork and were full of sludge. The elastomers have held up well. Plenty of grease in there so nothing wore out. This fork as a pair of tiny ports for injecting more grease. Overall a good long lasting budget fork but with limited ability. Disassembly only requires a 1" 6-point socket. Good for a beater bike not up to single track duties or racing.
