Bicycle suspension servicing in South Wales.

contact us

e-mail - contact@suspensioninc.co.uk

tel: - 01685 647 395

opening hours

weekdays - 9.00 - 5.30

weekends - closed

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suspension inc technical

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basic terms

  • air spring - air is used to support the riders weight in an air driven unit. the feel of an air spring is progressive and will have a soft feeling in the first part of the travel and will stiffen up as the suspension is compressed.

  • coil spring - a physical spring is used to support the riders weight in a spring driven unit. with a coil spring the suspension has a liner feel to it, meaning that the feel of the unit through it's travel feels the same all the way through until it bottoms out.

  • compression - this is the movement of the spring as it is compressed from rider interaction with the terrain

  • rebound - this is the effect you feel after the fork/shock has been compressed.

  • bottom out - this is what you feel when the suspension unit compresses to the very end of the travel and cant go any further. it will feel harsh as the travel of the suspension unit comes to an abrupt hault.

  • top out - this is the opposite of bottom out and occurs when the suspenion unit returns to its uncompressed state very quickly and will be accompanied by a clunk

  • travel - this is the term used to describe the movement allowed by the suspension unit.

damping

  • compression - this controls the way the fork is able to be compressed, compression can be adjusted by the rider to suit. there are different types of compression damping depending on the fork you have.

  • high speed compression - this is the part of the damping that controls how the unit compresses on bigger faster hits.

  • mid speed compression - this controls the unit once the initial damping has been used up

  • low speed compression - this is the control used for the smaller bumps on the initial part of the stroke.

  • rebound - this controls how the fork returns after being compressed, this also can be adjusted by the rider to suit. 

  • low speed rebound - this controls the units return after hitting smaller bumps at all speeds.

  • high speed rebound - this controls the units return after hitting larger bumps at medium to high speeds.

technical terms

  • sag - this is the amount of travel used up by sitting on the bike while it is stationary. obtaining the correct sag is essential for correctly working suspenion.

  • preload - this is the pressure the spring is under before you sit on the bike. the more preload the less sag, less preload more sag.

  • air assist - by adding extra air to a coil spring assisted shock you can add more preload.

  • platform - if a shock has a platform then there is usually no need for a lock out. it is used to help with pedalling efficiency while still allowing the unit to remain active.

  • cvt - this stands for control valve technology. it is the same as spv below but by a different name.

  • spv - this stands for stable platform valve, a pneumatic piston which closes the oil ports during pedalling and opens up on bigger hits.

  • lockout - depending on the manufacturer or unit model this either locks the unit out completely stopping it moving all together or makes it very difficult for the unit to be compressed at all.

  • ifp -  stands for internal floating piston and seperates the oil from the gas (nitrogen) that is in the damper body.

  • ssd or ssv - stands for speed sensitive damping and allows the damping to increase at faster speeds.

  • linear rate - this means that the feel of the unit remains the same all the way through the travel. more common in coil spring systems.

  • progressive rate - this means that the unit feels stiffer coming towards the end of the stroke. more common in air spring systems.

  • falling rate -  this is the opposite to a progressive rate and is more difficult initially to compress then becomes less resistant the more the unit is compressed.

  • bottom out resistance - this increases compression at the end of the stroke so you do not get that harsh bottom out feeling.

 

set up

 fork sag setting (you should always measure the sag with all your riding gear on and any compression turned off)

  1. with the stanchion "o" ring set against the fork seal sit on the bike (get some one to help you with holding the bike as you should not move the suspension when getting off the bike as this will give a false reading) then get into the "attack" position, pump the forks several times to get rid of the stiction and then remain stil for about 20-30 seconds to allow the fork to settle.

  2. carefully get off the bike ensuring the fork does not move at all, this is critical for an accurate reading.

  3. measure the distance travelled, you are roughly looking for a measurement of 20 - 25% for xc and as much as 35% for enduro and downhill, but this is a personal prference. you can then adjust the air or spring preload in the fork until you get the correct reading, adding more air/preload for less sag and removing air/preload for more sag.

  4. once the desired measurement has been achieved, you have set your sag.

 

 rear shock sag setting

  1. again with all riding gear on make sure the rear shock is set with no preload or platfoms set to on and that the "o" ring is tight up against the scraper lip of the shock.

  2. get on the bike and bounce up and down a little to relieve stiction and stand in the "attack position".

  3. leave the shock settle into position.

  4. again carefully get off the bike ensuring you dont push down on the rear shock at all giving a false measurement.

  5. measure the distance travelled between the scraper lip and the "o" ring.

  6. then work out what the distance should be between the scraper and the "o" ring on the shock stachion/body tube. see example below.

  7. add or remove air and repeat the steps until the desired measurement has been achieved and your sag is set.

 

 for example, if you are aiming at getting a 25% sag setting and your shocks active travel is 50mm, then your sag setting will be 12.5mm. worked out like  this - 50 / 100 x 25 = 12.5 or active travel of shock / 100 x the desired sag = resulting distance between scraper and o ring. 

 

 fork rebound setting

  1. now you have set the sag, dial the rebound right back to the minus position or fully open.

  2. push down on the forks several times and they should feel very active and bouncy.

  3. as you push down on the fork pick the front end up quickly, the forks should just about be leaving the floor before extending back to full travel.

  4. if this is not the case turn the rebound dial to start 2-5 clicks so as to start the process of dumbimg down the forks return after being compressed.

  5. keep going 1 or 2 clicks at a time until the fork feels more under control and you are happy with how they return to full travel.

  6. your rebound is now set, fine tune by riding the bike and seeing how it feels on the trail, further adjustment may be necessary.

 

 rear shock rebound setting

  1. ​again, ensure the rebound is set to fully open and there is no rebound control active on the shock.

  2. add a few clicks so that the return to full travel is not too fast and topping out and not too slow and packing down

  3. add or take away clicks one at a time to attain the desired feel.

  4. when it is feeling right you have set your rear suspension rebound.

 

 what you are looking for is for the rear wheel to stay on the ground and track over the terrain after repeated hits. you dont want it bouncing back up and  leaving the ground as this could push you over the bars. on a jump the rear should absorb the hit and return in such a way so as to be ready for the next hit  but not fast enough that you feel you are being bounced up and over. again fine tune by riding the bike on the trail where further adjustment may be  necessary.

 

 compression settings

  1. set the compression to fully off.

  2. if you are blowing through the travel when riding, braking or on landing jumps and the forks are dipping into its travel way too easy, add some clicks on the low speed compression dial, this should stiffen up the initial feel of the fork and give you more of a platform before going into its travel

  3. if you are using most of your travel on bigger square edged bumps and blowing right through to the top of the fork crown from the mid stroke then the high speed compression dial needs to be adjusted allowing the fork to ramp up towards the end of the travel

  4. adjust both dials if you have them to get the desired feel and again get out riding on the trail to see how they perform in real life and asjust as necessary.

 

 note: that if you dont have high and low speed compression adjusters but just a more simple single knob with a plus and minus setting on, then the lesser  the amount of compression added (knob set to the - end of the setting) the easier the fork will compress and the more the amount of compression added  (knob set to the + end of the setting) the harder it will be to compress the fork.