TMD Tuning Guide
Important Notes
Rimpact recommends that all service and installation work be carried out by a professional mechanic. Please see our warranty terms and conditions for guidance on coverage and usage terms.
Always install your TMD in accordance with the installation procedure outlined on this website. Periodically check the torque on the retention bolts with a torque wrench.
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It is necessary to run at least one spacer that sits proud of the steerer tube to allow the TMD to create compression over the headset.
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Always ensure the two bolts of the TMD are torqued to 4Nm or to the headset manufacturers recommended settings, which ever figure is higher.
What springs should I run and how do I change them?
The TMD's Mass needs to be free to travel as far as possible, as often as possible, when riding the bike. The stiffer the spring, the more the mass is inhibited. As such, the recommendation is to run the softest spring rate you can, until you notice the springs bottoming out inside your head tube. This will feel like chatter and is noticeable. When this happens, go up a spring rate. If you aren't noticing any rattle when you hit the largest impacts on a given track or ride, go down a spring rate. By allowing the mass to move as freely as possible, the time in which the input energy can be 'smoothed' is increased, resulting in increased performance.
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The TMD ships with Medium - Orange springs installed. Start with these and then go up or down from there. It is expected that some riders will only ever need one spring rate, where as some may need to fine tune when they go from mellow trails to bike parks and back.
How Do I Change the Springs in my TMD?
To change the springs in the TMD, remove it from the bike first. Place a 5mm allen key in the main bolt of the TMD and using a 12mm spanner, socket or adjustable wrench, loosen the connector nut from the bottom. As the springs of the TMD are under preload, the springs will decompress when loosening the connector nut and push outward. When the connector nut reaches the end of its thread, cup your hands around both ends of the device to keep all the components together. The preload is not so much that there is significant risk to health as it is not enough to become a projectile.
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Once the connector nut has been removed, replace the two springs with the desired set (Yellow = Soft, Orange = Medium, Red = Firm) and prepare to reinstall the washer and connector nut.
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You'll notice that the spring sits proud of the end of the main bolt, preventing easy re-installation. There are two main methods of compressing the springs to expose the thread. The easiest is to put the TMD upside down on a flat surface and have a second person push the mass down with two hands, compressing the springs and exposing the thread for the other person to put the washer and connector nut on. Rotate the connector nut a few turns until around 5mm of thread is captured before the first person releases the mass. Then using the same tools you used to remove the connector nut, tighten it until it bottoms out at the end of the main bolt thread. Torque to 4nm.