Tuning your Mountain Bike

For young lighter riders, we have created custom suspension forks to ensure that our Push the Limits mountain bikes perform perfectly regardless of a rider’s weight.

Riding a mountain bike with suspension is different to other bikes as the suspension needs to be set up in line with the rider. Incorrectly set up suspension is common among riders, but it isn't difficult to do if you take your time and set it up properly according to the needs of the individual rider.

Setting the sag is the first and most important step to dialling in the suspension on your child’s mountain bike. If it is set up wrong your little shredder will be fighting a constant battle with their bike and the terrain.

WHAT IS SAG?

The sag is the amount the suspension compresses when a rider sits on the bike. The amount of sag is specific to each bike and each rider. If there is too little sag the bike will lack grip, and if there is too much sag the bike will respond poorly. For trail riding, fork suspension works best when the sag is set between 20% and 25%.

For example
  • The Frog MTB 62 has 65mm travel in the forks so the sag would be best set between 13mm (20%) and 16mm (25%) when your child is on the bike.
  • The Frog MTB 69 and MTB 72 have 100mm travel in the forks so the sag would be best set between 20mm (20%) and 25mm (25%) when your child is on the bike.

MEASURING THE SAG

We always recommend that you set the sag with your child standing up on the bike. Follow the four steps below to set the sag:

  • Step 1

    Before you start, you will need to slide the rubber O-ring travel marker around the fork/shock stanchion down to the seal.

  • Step 2

    Get your child to stand up on the bike on the pedals whilst leaning the bike against the wall (Do not hold the brakes whilst doing this as this could give an incorrect reading).

  • Step 3

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  • Step 4

    Get off the bike carefully and measure how far the O-ring has moved from the top of the seal up the stanchion. The measured distance is your sag, which should sit around 20-25% of the total fork travel.

ADJUSTING THE FORK

Now that you have measured the sag, you might need to adjust the fork. To do this follow the four steps below:

  • Step 1

    Unscrew the valve cap on top of the fork (blue cap, on the Frog fork). This will uncover a valve, which the shock pump can be screwed onto.

  • Step 2

    Screw the fork/shock pump onto the fork. Pump the fork up to the desired pressure level - see the table below. Do not exceed the maximum pressure for the fork.

  • Step 3

    Repeat the sag measure from the steps above.

  • Step 4

    If the level of sag is lower or higher, add air pressure in 5PSI increments to achieve perfect sag.

PRESSURES

RIDER WEIGHT PRESSURE

20-30 kgs
(44-66 lbs)

20-30 PSI
(1.38-2.07 BAR)

30-40 kgs
(66-88lbs)

30-40 PSI
(2.07-2.76 BAR)

40-50 kgs
(88-110 lbs)

40-50 PSI
(2.76-3.45 BAR)

50-60 kgs
(110-132 lbs)

50-60 PSI
(3.45-4.14 BAR)

60-70 kgs
(132-154 lbs)

60-70 PSI
(4.14-4.83 BAR)

FORK MAINTENANCE

The sag is the amount the suspension compresses when a rider sits on the bike. The amount of sag is specific to each bike and each rider. If there is too little sag the bike will lack grip, and if there is too much sag the bike will respond poorly. For trail riding, fork suspension works best when the sag is set between 20% and 25%.

If you don't take care of the mountain bike forks, it will cause them to degrade, especially if your child is riding off-road in muddy conditions. We recommend forks are cleaned regularly, and we recommend they are serviced, lubed, and tuned by a competent person or preferably at your local bike shop.