- Suspension fork selection
- Installing the crown race
- Cutting the steerer tube
- Lubing the fork
- Suspension setup
- Z1 bomber Alloy/BAM servicing
From what I can determine, the majority of people that have Marzocchi forks are happy. The general rule is to match the rear shock travel with the front suspension travel. For the Isis, that means a fork with about 4" (100 mm) of travel.
I bought the 1999 model Marzocchi Z1 Alloy fork for half price at closeout. I suggest really searching before buying because you can save ALOT of money on sale and closeout forks. Note: The 1999 Z1 Alloy has Formula standard disk mounts, this fork is compatible with the Hayes MN caliper 8" disk with mounting adaptor 98-14590 or Hope C2 disk with #4 caliper and 185 mm 6 bolt rotor.
Z1 forks are downhill forks whereas the Z2 forks are XC forks. The main differences are the amount of fork travel and weight. The Z1 forks have hydraulic dampers in BOTH legs whereas the Z2 forks have the hydraulic damper in one leg only.
Model Travel 1999 Z1 Alloy 100 mm 3.9 inch 1999 Z1 BAM 130 mm 5.1 inch 1999 Z2 Alloy 65 mm 2.5 inch 1999 Z2 Atom bomb 65 mm 2.5 inch 1999 Z2 BAM 80 mm 3.1 inch Note: not all forks have disk mounts and there are three mutually incompatible disk brake mounting standards.
- The Hayes standard, also known as 74 mm parallel mounting tabs.
- The Formula standard, also known as FS standard or 97 standard disk mount or 48 mm standard. Now pretty much obsolete but very common.
- The International standard or 51 mm standard.
There are some adaptors made by Hayes that will permit use of nonHayes disc mounts with specific Hayes brake caliper and rotor combinations. Hope brakes do not use adaptors but rather different sized calipers and rotors for different forks. Shimano/Grimeca are international standard only. For the consumer "standard" is anything but standard and no braking system is really compatible with any other.
I believe all 2000 model Marzocchi forks have international standard disk mounts.
If you want disk brakes on the front, make sure your fork, front disk brake and front hub are compatible BEFORE you purchase.
Tip: Suspension setup depends alot on rider weight. If you do not fall in to the "stock" weight category, remember to negotiate with your builder for the proper shock springs and fork oil before you hand over your money.
Purchase a 1 1/4" diameter PVC pipe slightly longer than the steerer tube. Grease the steerer tube liberally. Double check the correct side of the crown race is facing up. Using the PVC pipe to cushion the crown race from the hammer, gently tap crown race on to steerer tube.
Recommendation: Read about the headset before cutting.
I purchased the BikeNashbar 1 1/8" headset spacer assortment, (1.5, 2.5, 5.0, 7.5 mm spacers).
Install the crown race on to the fork and headset cups onto the frame. Slip fork into frame, add top plate and put on the nylon washer, slip on a 1.5 mm headset spacer and add the stem. Snug everything down. Mark the top edge of the stem along the steerer tube. Double check everything. Cut with a tube cutter. Apply pressure slowly to avoid ovalizing the steerer tube.
I've duplicated the basic headset installation instructions here because people not following the headset link might get confused...
Replace the 1.5 mm headset spacer with a 5.0 mm spacer. Now the steerer tube is 3.5 mm below the stem. Remove any burrs from the cut edge. Put on top cap, grease stem bolt and torque to 10 in-lb.
Tip:Use a nail file to remove any burrs and smooth the cut edge. This will help prevent nicking the O ring in the top plate.
Lubricate the stanchions with a silicon spray and silicon greasing the dust seals for peak performance. Silicon spray can be found at any auto parts store or possibly a hardware store. To silicon grease the dust seals, just pry them up with a small, flat screwdriver and swab out any dust with a Q-tip, then apply silicon grease on the underside of the dust seal. Be careful not to damage the stanchion tubes when lifting dust seals. This can be done with the fork still on the bike.
Note: Lithium based grease will damage the dust seals. Silicon spray is available at any auto parts store. Silicon grease is available in the plumbing department of Home depot.
Tip: Cover you disk brake pads & rotor with a towel while lubing to prevent overspray contamination of the brake pads or rotor.
Travel
Positive travel refers to how much the fork can compress from the unweighted resting position. Therefore, negative travel refers to the ability of the fork to extend past the unweighted resting position. As the fork and wheel rebound after impact or while dropping off a ledge, the fork extends past its normal resting position and compresses the negative/top-out spring, giving it more positive travel. Negative travel increases the overall travel of the fork without making the fork longer. All of the Bomber forks have negative travel that allows the fork to top-out smoothly and keep the wheel in constant contact with the terrain while adding to the legendary ‘plushness.’ Negative travel combined with the recommended amount of sag will insure the smoothest ride possible.
Spring
Coil spring rate is the force needed to compress the springs in the fork. Marzocchi provides its forks with springs for the average rider. All 1997 and 1998 forks come setup from the Factory with medium springs, and all 1999 forks have the ProWind springs. The 2000 model forks with 80 mm total travel and the Monster T use the Medium springs and all others use the Heavy spring setup. If the rider prefers a different setup, then the stock springs will need to be replaced.
Model Total Fork Travel Spring Length Color Rider Weights Spring Rate Marzocchi Part Number
Z1 '97 105 mm & 110 mm 185 mm none 145-180lbs Pro-Wind* 5141156 Z1 Alloy '98-'99 Z1 BAM '98 yellow 120-155lbs Soft 5141112 Z1 CR '00 Z1 Dropoff '00 white 145-180lbs Medium 5141113 Z1 QR20 '00 Z3 LT '99 red 170-205lbs Heavy 5141114 Z3 QR20 '99-'00 JR-T '98 green 195-240lbs X-Heavy 5141190 MR-T '98
Oil height
Oil height can be used to tune the spring rate in the Bomber suspension forks. The height of the oil determines the air volume in the fork and can be adjusted to compress the air as needed. Raising the oil height will create a smaller air chamber, causing the spring rate to become increasingly stiffer as the fork compresses. Decreasing the oil height will create more of a linear spring rate, relying mostly on the spring for compression. Adjusting the oil height is not a substitute for the correct spring rate and should only be used to fine-tune the spring rate. Do not increase the oil height beyond the maximum recommendations or the fork may be damaged during use. Oil height is measured from the top of the stanchions down to the oil, with the stanchions compressed and the springs and preload assemblies taken off of the fork. When changing the oil, be sure to cycle the air out of the fork to insure an accurate measurement.
Oil Height Chart 120-180 lbsl 180-200+lbs Z1 Alloy 45 mm 40 mm
Shock oil
The damping characteristics depend on the viscosity of the oil in the shock. The shock ships with a 7.5 wt oil. Depending on your weight, you may opt to change the shock oil to tune the shock response. Use Spectro Golden oil.
Rider weight Oil viscosity Spectro golden wt <140 lb 5 wt 85/150 140-180lb 7.5 wt 125/150 >180 lb 10 wt 165/150
Sag
Sag or compression preload refers to how much the fork compresses when the rider is in the normal riding position. Marzocchi recommends 10-20% of XC travel and 20-30% of DH travel in sag to provide the best overall ride. The easiest way to measure sag is to put a zip tie around the stanchion and then measure how much the fork compresses when the rider is in the normal riding position.
| Total Travel | Recommended Sag | |
| Z1 Alloy | 105 mm | 20-30 mm |
Put a zip tie around one of the stanchion and push it all the way down to the bottom seal. Sit on the bike in a riding position feet on the pedals. Get off the bike and see how much the zip tie moved. If it is more than the recommended sag, adjust the compression (Oval knob on each fork leg). Minimum preload is when the adjustment knob is unscrewed fully counter clockwise. Adjust both forks with an equal number of turns.. Repeat until you get the desired amount of preload.
Rebound Damping
Rebound damping controls the rate in which the fork is able to extend. All of the Bomber forks have adjustable rebound damping. Rebound damping should be set as fast as possible, without causing a sudden, harsh force back to the rider. This will allow the fork to comfortably extend to full travel as soon as possible after impact.
It is a good idea to get a feel for how the different rebound adjustments affect the fork. On forks that have external adjusters (screw in center of compression adjuster knob), try turning the adjuster all the way counter-clockwise to the fastest rebound setting and then quickly compress and release the suspension several times. Next test the fork with the adjuster turned all the way clockwise and then somewhere in between. This will demonstrate the differences between damping settings.
Tip: "Heavy" guitar pick is a good rebound damping adjuster tool.
Forks using the SSV system can change their rebound damping with oil viscosities. Stock oil is 7.5 weight, so changing to a lighter oil (Example: 5 wt.) will increase the rebound speed. Heavier riders using stiffer springs may want to adjust their rebound speed with a heavier weight oil. Be sure only to use a high quality motorcycle fork oil like Marzocchi’s Factory Fork Oil. Refer to the Setup Chart for recommended settings.
Forks that have the SSV adjustable system can adjust the damping via an internal adjuster through the stanchions. When looking down into the stanchions, turn the adjuster clockwise to slow the damping and counter-clockwise to speed it up. Refer to the Setup chart for recommended settings.
Forks that use the SSV cartridge system benefit from an external damping adjuster located in the center of the colored spring preload knob. The small rebound knob has a screwdriver slot to aid with adjustment. Turning the adjuster clockwise will slow the rebound speed and therefore turning the adjuster counter-clockwise will speed up rebound. The damper has a total of 9 turns. Refer to the Setup Chart for recommended settings.
Compression Damping
Compression damping is the oil flow resistance felt when compressing the fork. Compression damping is categorized in two ways: low speed compression and high speed compression. Low speed compression refers to when the fork is compressed slowly and gradually, for example during rolling impacts and rounded bumps. High-speed compression refers to the resistance felt during multiple, hard impacts and square-edged bumps. The Bomber’s SSV system automatically adjusts damping depending on direction change and rate of travel. Therefore, Bombers can be setup very plush and supple and yet still resist bottoming.
It is better to be conservative while setting the compression damping because the spring offers resistance to compression as well. Too much compression damping creates a harsh ride because the suspension cannot compress rapidly enough to absorb large impacts. Compression damping is not a substitute for proper spring rate and should not be adjusted until the fork has the proper spring setup for the rider.
Marzocchi has introduced the new adjustable compression cartridges in selected 2000 models. Use the external adjuster located in the middle of the spring preload knob to change the compression damping. Turning the adjuster clockwise will increase the compression damping and therefore slow the compression speed of the fork. Consequently, turning the adjuster counter-clockwise will speed up the compression damping.
Forks that do not have an external compression adjuster can modify their compression damping by changing the oil viscosity. Although most riders will be happy with the stock compression settings, some riders may prefer a different weight oil to coordinate with rider weight and/or spring setup. Keep in mind that changing the oil viscosity will change the entire damping range and will affect rebound as well. See Setup Chart for recommended settings.
| Model | Rider Weight | Spring Rate | Rebound* | Compression** | ||||||
|
145-180lbs | Pro-Wind | 3.5 turns | 7.5wt oil | ||||||
| 120-155lbs | Soft | 5 turns | 5wt oil | |||||||
| 145-180lbs | Medium | 4 turns | 7.5wt oil | |||||||
| 170-205lbs | Heavy | 3 turns | 10wt oil | |||||||
| 195-240lbs | X-Heavy | 3 turns | 10wt oil |
*The rebound settings indicate the number of turns out from fully closing the damper (turning it clockwise until it stops.)
**The compression settings are indicated by oil viscosity or by the number for turns in from fully opening the damper (turning counter-clockwise until it stops.)
