How to convert SHIMANO Shadow Plus RD into 9-speed

Nov 23, 2012 at 13:45
by Shin Tanaka  

Shadow Plus RD has the best ever feature on its entire development history.
Its one-way clutch delivers desired silence and jam free riding on trails.
Only the disadvantage is that the feature is applied only on Dyna-sys or 10s drivetrain.
I would like to explain all the way to make the dream comes true for the person who desired to use Shadow Plus RD
on 9s drivetrain.


First of all, I have been running SLX(RD-M675-GS) with SAINT 9s Shifter(SL-M810).
It works OK while putting aside that I should double tap the lever when needed and could not use the two sprockets
on the lower side (in my case; 34T and 30T) while climbing.
I used to ride like

( 34T - 30T ) - 26T - 23T - 20T - 17T - - 15T - - 13T - 11T

"-" means a single click on lever operation

Saying it simple, it works as 7-speed.
So, as SHIMANO already said, Dyna-sys is completely no-compatible with 9s drivetrain components.

I have been trying to get used to that, but I found the forum:

Hochspannung für alte 9-fach Schaltwerke: Die Geschichte vom “Kettenglück” on IBC
http://www.mtb-news.de/news/2012/11/14/hochspannung-fuer-alte-9-fach-schaltwerke-die-geschichte-vom-kettenglueck/

Although the best solution is shown; dig a hole on the RD, but I am wondering mis-machining.
Then the idea comes to my mind.

Fortunately the difference between Dyna-sys and 9s is only the leverage ratio.
Leverage Ratio is only determined by the Length shown as A and B in the following picture.
Description on Leverage Ratio and the Length
To make the high quality conversions, we need to determine the exact Length by shortening from B to A.

I think it is hard to measure the accurate length, because it depends on each model, but it is not the exact target.
So I will show how to determine that but for only telling the number of the length here
The main target is how to get the accurate leverage ratio.
We need to determine the exact Length A to achieve this!

So...

Here is the listings to prepare:
- Brand-new gear inner cable
- Zip-Ties (called simply as Ties for later instructions)
- Proper sized Phillips Head Screwdriver
- A tiny Flat-bladed Driver or Needles to release locking of a tie.
- Knowledge on how to adjust SIS on RD


Step 1: Set the capacity of swinging range.
Simply follow the SHIMANO instructions on SIS TOP/LOW adjustment.

Step 2: Tighten the clamping bolt
Tighten the bolt which clamps inner cable at proper length on the smallest sprocket.
This step determines the tension on the cable. No big adjustment needed so far if you have done this correctly.

Step 3: Set Ties
Set Ties shown as below.
Do not over tighten these ties as shown in picture on this step.
These Ties are called Ties A, B and C for later instructions.

Note that Ties are well positioned as shown in the picture.
Of course, this is only an example.
If you could find the better position, like set Ties around lever pivot, it must be better.
But as I experienced, positions of zip-ties may be restricted by its width.

Step 4: Push the chains on the largest sprocket
Pull the inner cable all the way up by operating the lever on rear shifter more than 8 times.
Pushing RD towards the brake rotor side while turning the cranks for a while will help you to do this easily;
I call this technic "RD Push" for later instructions.

Step 5: Tighten Tie B and C to preset the Length
Tighten Tie B and C as far as you can till the upper pulley get well under the tooth of the largest sprocket.

Step 6: Tighten Tie A to hold the Length
Tighten Tie A well enough to hold the Length A and support Tie B.

Step 7: Determine the exact Length A
This is the most important and difficult step but you can achieve that by following the instructions shown below.

In this step, you need to find out the right spot on the Length A by tightening Tie B and C.

Process Flow:
1. Set chains on the largest sprocket by using shifter (fully pull the inner cable) and do the RD Push.
2. Fully release the inner cable by using shifter to RELAX the cable around Ties B and C.
  DO NOT turn the cranks!
3. Tighten Tie B or C slightly.
  DO NOT over tighten! A single click on the tie makes big change!
4. Set chains on the smallest sprocket by turning the cranks for a while.
5. Check that every each click on shifter does only a single gear shift.
 If not, repeat whole process, from 1 to 5, until you get the right spot.

Note that If you have over tightened Ties, they won't let the RD move enough to set chains on the smallest sprocket.
Technics that relaxing ties by using needles might help you.

Step 8: Confirmation
Do the fine adjustment on the inner cable tension following the instructions from SHIMANO.

Step 9: Finish
Test riding is always needed!
If it works in real world, finish up these steps by cutting off the extra length of ties.


Unfortunately, this work takes up much more time than regular installation when replacing whole gear cable or
only a inner cable.
Every time you replace a cable, every time you need to do this.
Since zip-ties are easy to break when received high intensity impacts, this trick might not be last long enough.
But it delivers benefit you desired for and I hope you will soon get used to this.

Please put your comments on detailed technics you did or the Length A on your set up.
It will makes others easy to find out the right spot.
Any other great ideas are welcome!


Hope you enjoyed!
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2 Comments

  • + 1
 In the time you took to work that out and post it on here you could've worked an extra shift and bought a 10-speed shifter...
[Reply]
  • + 1
 You could try using a stainless steel tiny hose clamp. Screw adjustable too.
[Reply]

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