Aftermarket Suspension Linkages

A lot has been touted and talked about with the aftermarket linear race linkages. Originally available from Moriwaki and then from Kyle Racing the linkage alters the rising rate of the swingarm making its travel much more linear.

The OEM link by default is designed to carry both a rider and a passenger so having a more progressive curve insures that the bike can handle a much broader range of rider weights. Installing an aftermarket linear linkage ultimately gives the rider a better tuned suspension for riding solo and more compliance from the rear wheel which translates into more grip while on the throttle exiting the turn.

There has been a lot of misconceptions about the linear link so after 10 years of listening to rumors on the message forums I finally decided to come back to the old website here and set a few things straight:

 

1. The purpose of the linear link is to alter the rising rate of the swingarm period. It is true that it also increases the rear ride height at the axle by about 14mm, but this is purely a by-product of design not the original intention.

2. The linear link does work with the stock OEM shock, but the stock shock is a piece of crap not even worth its weight as a boat anchor. You would be much better off with an aftermarket shock without the linear link than trying to use the linear link with the stock shock.

3. The linear link works best on the SP1 swingarm. It works great on the SP2 swingarm as well, but it really shines on the original 2000-2001 designed units.

4. The link does not work as well with other brands of aftermarket shocks as it does with the Ohlins. I get accused of being biased about this and trying to sell more Ohlins shocks, but I assure you that is not the case. I have tested the link extensively with Penske shocks along with many others as well and the contrast to the Ohlins is HUGE. It's not that the link is a detriment to the handling when using a different brand than Ohlins it is simply that it does not offer the same benefits as it does with the Ohlins. It took me years to figure out why, but I have pretty much narrowed it down the fact that the Ohlins shock uses an internal top-out spring while the other brands of shock do not. I believe the topout spring slightly alters the way the shock moves when using the linear link and that speed of the geometry change is the key to the disparity in performance as the shock extends and comes back down. I've heard others claim that various aftermarket shocks can be purposely rebuilt with a different valving (i.e digressive vs linear) to accomodate the link, but then that does not explain why the Ohlins shocks excel with both the OEM link & aftermarket links without any additional valving changes.

5. If you install an aftermarket linear link you will need a stiffer spring rate than you currently use on your Ohlins shock. One rate higher will be sufficient.

6. As you approach the rider weight of about 220lbs (without gear) or more the effect of the link starts to work against you. For starters it becomes increasingly difficult to find a spring stiff enough to compensate for the more linear rate of the linkage. Springs of that heavier rate have thicker coils and sometimes the larger coils tend to rub the inside of the swingarm and grind away at it, in some cases coil bind has been a problem as well. This effect is increased as the spring compresses and bulges out of its normal shape. Additionally due to the heavier rider weight riders will find that with the link they can get their rider sag numbers set properly while sitting static on a flat level surface, but when the bike is in motion the shock ends up riding in a different area of the stroke causing issues with the rear end squatting to much which in return causes the front end to rake out which pushes the front. Ground clearance issues can also occur as a result of this.

Here is the chart of which spring you should use with & without an aftermarket linkage

Rider Weight in Gear Nm Spring Rate with OEM Link   Nm Spring Rate with Aftermarket Link
140-160 85   90
160-180 90   95
180-200 95   100
200-220 100   105
220-240 105   110
240-260 110   Not Advised
260-280 115   Not Advised

 

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