Tarmac: Rear Derailleur and OSPW

After the SRM Power-Crank now for another new gadget. An OSPW manufactured by Ceramicspeed paired with the Dura Ace R9100 Rear Derailleur.

The Scholars contend about the advantages and necessity of oversized pulley wheels but I think… why not?! The watt saving aspect is more a mental thing. Of course there is a lower friction because of sizing and ceramic bearings but not really measurable.

My main reason for the OSPW by Ceramicspeed is the visual aspect, second the “no compromise” slogan on the Tarmac.

Post as guidance? No warranty in ANY case of damage!

OSPW stands for OverSizedPulleyWheels. The mystery behind those larger jockey wheels is a lower friction caused of less contact between the chain and the wheel. Paired with ceramic bearings the amount of watt saving should be around 3-5 Watts (statement by Ceramicspeed).

Because I ran the OSPW since 2019 (yes, i know… no blog entry) a service should be done during the reassembly. Because there is no documentation of the initial installation I remounted the original hanger, to replace it again.

But first, let’s start with the OSPW service. 

After loosen the four screws it is possible to unclip the idler pulley wheels. First step in service is to clean the cage.

To maintain the bearings it is necessary to remove the bearings on each side. Every pulley wheel has two bearings. Best way is to lever the bearings with a cutter but make sure you do not damage the bearing itself.

Next step is easy – drop every thing in a cup or shaker and fill it up with degreaser. Shake it and let it rest for about 2 minutes.

After that take every thing out and wipe it down. To make sure every thing is dry let the wheels spin and rest for another 2-3 minutes. 

Now that the bearings are clean and dry they would taken damage. So a special low friction pulley oil is needed (by Ceramicspeed). Just two drops in every bearing nothing more. Reinstall the bearings and let is spin for a final one in your hands. Everything should run smoothly.

Now the service part is finished. Time for the reassemlby.

First are the pulley screws (2.5mm Allen), correct torque 1-2NM. After that the 2mm screws with 0.7NM. Like new…

Now for the weight check.

  • OEM Derailleur: 160.6 grams
  • Ceramicspeed OSPW: 77 grams
  • OEM Hanger: 46.1 grams

The final assembled rear derailleur will hits the scale with 191.5 grams. But weight is not everything…

Finally the installation of the rear derailleur.

The only thing that should be mentioned is that there should be no gap between the hanger and the derailleur. Torque is 8-10NM.

Now for the fun part: OSPW installation.

First step is to unscrew the stop Screw (PH-1), while you are holding down the hanger. After that a second screw must me removed. This is the retention screws (TX10). After that it is possible to unload the spring of the hanger clock-wise and remove the hanger itself.

Side-by-side comparison of the Dura Ace and the OSPW hanger. The Cermicspeed OSPW for the Dura Ace R9100 has an integrated stop screw (left) so the oem can be droped. Only the retention screw needs to be reinstalled (right).

To make the OSPW work the spring needs to be transferred. A good mix of chain tension and shifting performance is the second hole from the bottom up. Remeber: Do not forget the gasket (right). This covers the spring from dust and grain.

Installation is a little of replay. Insert the OSPW hanger and make sure the gasket is in the right position. Then set up tension on the spring counter-clockwise till it passes the stop. It is important to keep the pressure on the OSPW hanger. Then insert the retention screw and torque it down to 1NM.