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F450 CHASSI AND GEOMETRY


CRF450 - F450

Race Tech is a G.M.D. Computrack Center and has been involved with the suspension and chassis geometry development since shortly after the beginning. Gavin has mentioned our work on his blog and I have been answering emails. The purpose of this page is to explain the developments here at Race Tech.

The most critical part of the conversion to a F450 road racer is the geometry setup.  The geometry setup hinges on the front end.  If the front end is too short the proper rake, trail, and anti-squat on the rear can never be achieved.  Ground clearance will suffer as well.  Sport Bike front ends are all too short by around 100 to 125mm (4 to 5 inches).  The best possible solution is to re-work the stock forks and change the triple clamps on the front end. 

Since dirt bike forks all have a leading axle the triple clamp offset must be radically changed.  Stock triple clamp offset on dirt bikes range from 20 to 25mm.  Race Tech F450 Triple Clamps are minus 2mm from zero.   This means we are changing the offset by 22 to 27mm.  This is huge, but necessary, for proper front end grip.

The forks must be shortened and the bottom-out point must be changed at the same time.  The fork springs are custom made to order from our existing stock.  In the case of the Twin-Chamber Forks we machine new locating grooves for the spring perch as part of the shortening process.  The hydraulic bottoming-cone is far too long and is abandoned in favor of an elastomer style bottom-out.

The exterior of the stock forks between the triple clamps is tapered.  This area of the fork tube is machined straight so clip-on handlebars can be used.

We highly recommend replacing the left fork bottom with an Extreme Riders Radial Mount Fork Bottom.  This provides a very strong and clean mounting of a 108mm sport bike brake caliper (standard Japanese bolt spacing).  You have the option of buying a matching fork bottom set.  These billet machined fork bottoms are very high quality.  For some models you will need to buy both a left and right fork bottom as they have odd offsets.  Since the bike is so light, a 280mm single disk is quite adequate for this application while a dual disk can be touchy (as well as heavier).

The RT Triple Clamps are 200mm wide.  This is wider than the stockers for tire clearance and requires a longer axle.  If you bring the bike into Race Tech we can machine custom axle and disk spacers to insure proper wheel alignment.  If you send in your suspension components you will need to handle this on your own.  However if you are using Marchesini wheels we may have the spacers already worked out so we can ship you some.

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