Model year 2014
USER MANUAL
WARANTY
Terms and conditions
BOS MTB offers warranty on its products on the following terms :
BOS MTB guarantees to the original purchaser that the BOS product for which they
received this warranty is free from defects in material and workmanship for one year
from the date of original retail purchase. A proof a purchase will be asked for any
warranty claim. This warranty is not transferable to a subsequent purchaser.
Wear and tear parts such as dust seals, Oring, bushings, rear shock mouting
hardwares, stanchions, threaded parts and bolts are not covered under this warranty.
Terms
This warranty is subject to legal jurisdictional or warranty rights of the country where it
has been originally purchased, which will prevail if different from the terms herein
listed.
Limits
BOS MTB cannot be liable for any loss, inconvenience damages, whether direct,
incidental, consequential, resulting from the use of its products, local legislation
prevailing.
Warranty exclusions
This warranty does not cover the following cases:
• Damage to products resulting from improper assembly other than listed below
• Products that have been modified by the owner or a third party
• Improper use
• Damages resulting from an accident, crash under any circumstances
• Invalid servicing procedures and servicing time frame not respected
• Replacement of the original parts by parts from others manufacturers
• Products whose serial numbers has been altered, defaced or removed.
Warranty procedure
The owner should always refer to an approved BOS center for any warranty claim. A
proof a purchase is compulsory for any warranty claim. Otherwise the warranty claim
will not be considered. Always contact BOS MTB warranty department before returning
any products that may fall under this warranty. If “the faulty parts” do not fall under
warranty, the customer will be charged for any costs in respect with warranty such as
transport and package back and forth.
1. INTRODUCTION
Thank you for purchasing a Bos Void shock. Your shock has been assembled specifically for one bike - obviously
yours ! - which means that the internal valving and the air chamber volume are settled for your bike. The adequate
mounting kit is also provided with the shock.
CAUTION
Never try to disassemble your shock. Limit yourself to the instructions given in this manual.
This shock is pressurized, for your own safety, do not try to open it.
Contact an authorized service center for any maintenance operation.
2. ASSEMBLY
Your Void shock features adequate mounting kits for the bike mentionned while ordering.
Check the mounting way
by refering to the compatibility table, available on bos mtb website : http://www.bosmtb.com.
Refer to the bike manual
to follow the specific shock mounting procedures of your bike.
3. SETTINGS
3.1. AIR PRESSURE
Before using the shock, you must set up the air pressure, depending on your weight.
The air pressure is not related only to your weight but also to your bike’s rear suspension geometry.
Refer to the compatibility table on Bos mtb’s website, in the download area :
http://www.bosmtb.com to check the correct air pressure, related to your weight AND your bike..
Connect a pump equipped with a precise manometer to the Schrader valve located on the side of the upper part of
the body, and inflate at the right pressure.
Air valve
3.2. AIR CHAMBERS BALANCE
In order to guarentee a perfect functioning of
your shock, after having set up the air pressure,
you must proceed to the air chambers balance.
The shock must be mounted on the bike.
Place the O’ring at 11 mm from the seal of the
shock, sit on your bike, and push slowly on the
suspension, to compress the shock until the seal
come onto the O’ring.Let the suspension extend
itself, still slowly.
Repeat 15 times those up and down
movements, always at low speed.
11mm
3.3. CHECKING THE SAG
The SAG is the quantity of travel used while sitting on your bike, due to the effect of your weight. It has to be settled
up by adjusting slightly the air pressure.
BOS recommends a percentage of SAG of 30 to 35 %.
The bike manufaturer may also indicate a percentge of SAG. Please refer to your bike’s owner manual to check it.
If the bike percentage differs from Bos advices, please test on the track what is the best setting for your riding style.
How to measure and set up the SAG ?
Slide the O’ring onto the seal of your shock.
Sit on your bike (if possible dressed with your riding outfit) feet on the pedals - horizontal position, and let the sus<
pension compress under the effect of your weight. Get down from the bike, extend the rear suspension to the
maximum by pulling up the saddle, and measure the distance between the O’ring and the seal. This distance will
allow you to check the percentage of SAG obtained with the current air pressure. To convert the distance into
percentage, refer to the table below.
length x stroke (mm) 222x67 240x76 267x87
SAG (%) 30 35 30 35 30 35
SAG (mm) 20 24 23 27 26 31
If the SAG is not correct, slightly set up the air pressure, by 15 PSI steps.
Too much SAG : increase the air pressure.
Not enough SAG: reduce the air pressure.
3.4. HYDRAULIC SETTINGS
The Void shock is a three-ways type shock, which means there are three types of damping adjustment: rebound,
low-speed compression and high-speed compression.
Your shock’s basic setting (internal) is designed for your bike’s geometry. We use ten base settings which cover the
majority of bikes on the market. If a different setting is necessary for a given bike, we will develop it especially.
The purpose of damping adjustments is to use all the shock’s travel without bottoming-out (or only rarely), to give
grip to the rear wheel, but also to stop the bike stalling in holes, and finally to maintain a good position. Below are
the basic settings for your frame. Then it’s up to you to analyse its performance and adjust the settings to suit your
riding style. Do this carefully and methodically, step by step. Only change one setting at a time and only by a few
clicks. If it’s OK, note the setting and type of terrain. If you get confused with the settings, return to the basic settings
and start again.
3.2.1. Low Speed compression (A)
The low-speed compression affects the shock’s performance in
compression over small bumps or through the beginning of the travel.
It can be useful to make the low-speed harder (screw clockwise) on
rolling
terrain with big compressions and kickers.
It can be useful to make the low-speed softer (screw anti-clockwise) on
steep gradients.
3.2.2. High Speed compression (B)
The high-speed compression acts mainly on harsh hits (jump landings,
rough rutted sections). It should be soft enough to get all the travel
without bottoming-out. If, on a given track, you bottom-out a lot, make the
high-speed compression harder. However, don’t get hung up on
bottoming-out if you only do it once or twice during a run. You risk setting
your shock for 3% of the course and losing efficiency on the other 97%. If
your shock doesn’t get full travel, soften the high-speed compression.
3.4.2. Rebound (C)
The main factor in adjusting the rebound is the position of the bike. A
downhill bike shouldn’t be ‘sat-down’ all the time, although the back does
need to be fairly low. Playing with the rebound will allow you to keep this
balance.
If you feel like the back of the bike’s pushing you forward on a slope or
when braking, increase the rebound (screw clockwise). It can be useful
to accompany this adjustment (especially if the problem persists) by
unscrewing the low-speed compression slightly.
If, on the other hand, the bike seems too low at the back and/or the front
end has a tendency to drift offline, reduce the rebound (screw anticlockwise).
C
A
B
Starting points adjustments whatever the inner setting
Low speed compression : 12 clicks from the fully tighten position.
High speed compression: 17 clicks from the fully tighten position.
Rebound : 12 clicks from the fully tighten position.
Refer to the Void Charlist available on the download section on bosmtb.com for details about standard settings for
each bike.
CAUTION
Thanks to a good compression curve, the Void shock allows the bike to keep a good balance, a good response
and handling. Bos thus recommends to set up the bike with a fast rebound, to keep that chassis balanced, and
avoid the bike staying low, which means that it will be less nervous, and less comfortable.
The feeling of «fast» or «slow» rebound will be different from a rider to another one. Thus it’s difficult to define it
precisely. It’s related to your riding style. We advise you to define your own range of correct rebound - the range
of settings between «too fast» and «too slow». Then, always choose the faster part of that range, for example
the three last clicks (unscrewing) on a range of nine.
3.5. AIR VOLUME ADJUSTMENT
The progressive adjustment featured on the Void allows you to act on the air spring rate on the last third of stroke.
Therefore, from satisfying settings (air pressure and hydraulic) on the first half of the stroke, you can act on the last
mm of travel.
The most featured and simple cases are :
1. The shock has an overal setup to single out comfort and grip,and the bike is quite low: by increasing the rate, you
will get a better control of the chassis through the shock and avoid bottoming out. The rate curve is more
progressive (increasing in the end).
2. The overal setup of the shock is more responsive, with a chassis balance quite high. By decreasing the rate, you
can make sure that you use all the travel.
This setting is made through the o’rings placed inside the air chamber, by adding or removing some.
We suggest you to go step by step. At first, play with two o’rings, then end the setting more precisely, with one
o’ring.
By adding one o’ring in the chamber, the spring rate will increase of 2%.
Usually, the correct setting is made with 0 to 4 o’rings. But the range can go up to 10 o’rings depending on the
bikes.
CAUTION
Use only the o’rings provided by Bos. The material and the dimensions are specific.
Procedure
1. Install the shock in a vise using a soft jaws (1)
2. Tighten slightly to avoid damaging your shock
CAUTION
Make sure that the jaws are applied on a flat
surface and do not touch the rebound knob.
3. Take note of the current pressure in your
shock before deflating it. Take into account the
air loss, due to the insertion of the pump.
4. Unscrew and remove the air chamber cylinder
(2) et (3). Never use tool.
5. Remove the shock from the vise and separate
the air chamber cylinder from the shock body.
5. Place or remove the o’rings inside the air
chamber cylinder. Ideally, place them at the
bottom of the cylinder (4).
1
3
2
4
!
6. Before to screw back the cylinder, make sure
that the rebound knob and the sticker of the
main cylinder are perfectly aligned (5).
7. Once tighten, make sure that the cylinder (A)
and the top of the air chamber (B) come at the
same level (6). In case not, check if the valve
cylinder is well positionned.
5
6
B
!
A
3.6. AIR VALVE ROTATION
The schrader valve can rotate around the air chamber, but also be placed forwards or backwards, in order to fit into
any kind of frame.
CAUTION
Never place the valve in front of the reservoir. This could damage seriously your shock on the first compression
In order to adjust the position of the air valve to the front or to the rear or just rotating it, please follow the procedure:
Procedure
1. Install the shock in a vise using a soft jaws (1)
2. Tighten slightly to avoid damaging yout shock
1
2
CAUTION
Make sure that the jaws are applied on a flat
surface and do not touch the rebound knob.
3. Take note of the current pressure in your
shock before deflate it. Take into account the air
loss, due to the insertion of the pump.
3
4. Unscrew and remove the air chamber cylinder
(2) et (3). Never use tool.
4
5. if you need to change the position of the
valve, remove the valve ring and place it in the
right way (4).
6. Before screwing back the cylinder, make sure
that the rebound knob and the sticker of the
main cylinder are perfectly aligned (5).
5
6
B
7. Once tighten, make sure that the cylinder (A)
and the top of the air chamber (B) come at the
same level (6). In case not, check if the valve
cylinder is well positionned.
4. MAINTENANCE
Cleaning
Clean your shock after each ride using a non-aggressive, non-alkaline cleaning product, let it dry then spray with
silicon spray and protective grease. Check it regularly and remove any dust/dirt from the bottom-out bumper.
Cleaning Oil service Full service
!
A
Recreational use
after single ride once a year
Racing use once a year
Every 2 years
IMPORTANT
The oil service and full service must be performed by a BOS approved center. The BOS approved centers are
the only able to identify and appraise a damaged or worn part, especially in case of shock or wear on structural
elements such as the legs, the stanchions and the crowns.
IMPORTANT
Never attempt to alter the pressure in the shock’s reservoir.
It never needs to be changed and the gas only acts to pressurize the hydraulic fluid in order to avoid cavitation.
Attempting to modify the reservoir pressure will only result in shock failure.
5. FAQ
What is the basic set up ?
Your shock has been set up for your bike, with a specific internal valving and a specific air chamber volume. It is
delivered with a standard pressure of 80 to 100psi. You can find in the download section of our website all the infos
about standard settings for each bike.
There is air leaking when I connect the high pressure pump, what can I do ?
Check your pump : make sure that the shell of the shrader valve is correctly mounted.
My shock is too stiff on the first inches of travel and / or the rebound is very fast . What can I do ?
The balance between the two air chambers is not correct. Refer to chapter 3.6 to check how to set it up.
The valve is not rotating. How can I move it more easily ?
The purpose of the valve ring is not to move at any time. It has to be set up when you mount the shock on the bike.
You can change its position at any time, but you need to disassemble the air cane. It’s quite easy to make. Refer to
chapter 3.6 and follow the instructions.
Once reassembled, the stickers are not aligned. What can I do ?
To be sure that the stickers will be correctly aligned, the rebound knob must be perfectly aligned with the piggy back
when you start to screw the air chamber. Check it on chapter 3.5
I use the same settings than with my Stoy, but I feel a difference between the two shocks, is that normal ?
That’s normal. Even if the air spring of the Void acts like a coil spring, there is a small difference (which makes it
even more performing !). Thus you may feel a slight difference if you already experienced the Stoy. By adjusting
slightly the external settings, you will be able to find the best set up easily.
My shock features negative stroke. Is that normal ?
The air spring of the Void is designed to obtain the best sensibility on the first inches of travel. Thus, on a few bikes,
you may notice some negative stroke.
Where can I purchase original stickers and valve cap ?
You can purchase these items through your approved BOS center, or on bosmtb.com website.
I noticed some play between my shock and the frame, what can I do ?
The rear shock mounting hardwares must be replaced. Contact an approved BOS center, or connect on
bosmtb.com.
My shock is getting compressed when I deflate it, is that normal?
When you deflate your shock, you deflate only the positive air chamber. The negative air chamber is still
pressurized, it acts in the opposite way, and pulls the shaft. If you want to avoid it, deflate step by step (30 to 40psi),
and proceed to the balance of the air chambers between each step (5 to 6 slow extension moves, forth and back,
on 15mm).
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