TMD Installation Guide
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.
Important Notes
Always install your TMD in accordance with this installation procedure. 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. Your stem can also sit proud of the steerer tube as an alternative.
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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.
How to Measure for TMD compatibility
TMD requires a minimum steerer length of 180mm to be compatible. To check, measure from from the underside of your fork crown up to the top of your steerer tube where the top cap sits.
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Got a steerer shorter than 180mm?Spacers will need to go above the stem to be compatible, please get in touch if you need further information
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How to Install your TMD
Servicing the TMD:
The TMD is designed to be maintenance free for long periods. You can remedy a small squeak with chain lube or silicone spray. No lube is necessary to the function of the device. Keep it clean and it should work as intended for prolonged periods, maintenance free. Check semi regularly to ensure it is installed to torque and is running clean and smoothly.
Servicing Disclaimer:
We have made every effort to ensure the TMD is safe and user friendly when the usage and service guidelines are followed. However, if you are unsure of your ability, or the installation processes outlined in the video, please seek assistance from a professional mechanic before proceeding. There is a risk of injury and risk of injury to yourself or others associated with improper installation or servicing of this device. Do not perform any modifications or adjustments to your TMD unless instructed by the guide or one of our expert team. Springs under compression can be dangerous if not properly secured. Always wear eye protection when removing or installing springs. ​
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Text and Picture Installation Guide
Tools and equipment you'll need to service your TMD:
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A clean work environment
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Eye protection
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2X 5mm Allen keys and a torque wrench
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A mallet or starnut removal tool (if you need to remove your starnut).​​​​​
Prepare
To begin installing the TMD, we recommend achieving preload over your headset with your existing starnut if you've already got one installed. Then remove the top cap only, maintaining the stem clamp and preload over the headset. This isn't mandatory but can make the process easier. Wrap a clean rag around your fork seals to prevent any dirt or metal shavings from getting caught on your seals. Also, plug the end of your steerer with shop towel if you are going to remove your starnut. If you don't have one, skip down to the Installation header.​
Star Nut Removal
If you need to remove your star nut, we recommend using a star nut puller. If you don't have one, it is possible to remove the starnut using a few methods. Ensure the fork seals are protected and there's a shop towel in the bottom of the steerer to catch metal shavings. Loosen the stem pinch bolts or remove entirely to avoid damage.The most recommended removal method is to create a puller using a large socket that sits on the steerer, a washer and a bolt. Screw in the bolt and the tension will pull the star nut from the steerer. A visual reference for this can be found in the video above.​
The second method is to drill out the rivet in the star nut to allow the nut to be rotated sideways and extracted. A 8-10mm drill bit is needed for this method. Finally, the third method is to knock it through the bottom of the fork. This is the last method we recommend due to the damage it can cause on the inside of the steerer. Whilst not likely to be structural, it is unsightly and could create sharp burrs. Use a long bolt/impact pole to knock it through, being very careful to keep it centered. ​
Installation
First ensure the stem is installed and there is either stem or spacers sitting proud of the steer tube. This is necessary as the top cap needs to be able to pre-load something against your steerer, if it contacts the steerer tube it will not be able to. We recommend at least 2.5mm of material sitting proud.Place the TMD into steerer. Thread the extension bolt into the Steerer cap and then place this into the the steerer from the bottom, holding it in position. Thread the two parts together until tight.
​Take a set of calipers or a ruler and measure the distance between the bottom of the steerer tube and the underside of the Steer Cap of the TMD, as shown in the photo. Ensure the TMD was being pulled taught when the measurment was taken. Measure 3 more times, once you cut the bolt wrong you can't add more length and will need to buy another.
​​Take this measurement and add 3mm to this number. This is to allow the bolt to tighten and not bottom out, but also to account for error in measurement. Now remove this bolt from the bike and the steerer cap. Measure from the end of the bolt thread towards the head of the bolt and cut this amount off of the bolt using a hacksaw. Put the bolt in a bench vice to secure it correctly before cutting. An 8mm Nut or two can help the vice clamp the bolt if you don't have soft jaws and also open the thread up once cut. A light chamfer on the thread to remove the sharp point is recommended. ​​
Once, cut, reassemble and check you are able to tighten the bolts down. If you maintained the headset pre-load using your stem pinch bolts, tighten both TMD bolts to 4nm and complete a 'car park' test to ensure the TMD remains in place, there are no rattles and the pre-load is maintained. If you lost headset pre-load during installation, simply install the fork, stem and spacers as per usual and tighten the TMD down like you would your star nut. When adequate preload is achieved, tighten stem and crown pinch bolts correctly. Once done, you can increase the TMD torque if required to ensure a tight fit.