Since the mid cage 105 R7000 rear derailleur is not suitable for the United Trifold, I had to find another set of components which will better suit the small wheeled bike.
The problem I faced previously was insufficient ground clearance, as the mid cage rear derailleur had a rather long cage. Therefore, I decided to get a rear derailleur with a really short cage, to solve this problem completely.
What I know is that the Saint or Zee rear derailleurs from the downhill groupsets have the shortest cage, which is why I decided to try the Saint rear derailleur on the United Trifold.
However, as the Saint rear derailleur is a 10 speed component, this means that I need to change the cassette and shifter to a compatible 10 speed type. For convenience's sake, I will continue to use the 11 speed chain first. The chain ring and crankset does not affect compatibility.
Saint RD-M820 rear derailleur
Super low profile! Barely sticks out from the side.
Really long inner link arm, as the cable pitch for MTB is longer than road. The high and low limit screws are located far apart from each other.
Super short cage! I forgot to measure the length, but it is really short. Definitely no problem with ground clearance.
As a MTB downhill component, it comes equipped with a clutch. Nice to have but not necessary.
Weighs a pretty chunky 271 grams, due to the extra robust construction for downhill riding.
Side by side comparison with the previous R7000 mid cage rear derailleur.
Big difference in cage set length and also inner link length.
Here is a 11-28T 10 speed cassette, similar to what I used many years ago on the Dahon Vitesse 2x10 speed setup.
105 5700 11-28T 10 speed cassette weighs 249 grams
Installed onto the wheelset with no issues. A 1.85 mm + 1 mm spacer is needed at the back of the cassette.
Looks good on the wheelset!
Next, I need a 10 speed MTB shifter, as it needs to be compatible to the 10 speed MTB Saint rear derailleur. A Tiagra 4600 road flat handlebar shifter is not compatible due to the different cable pitch.
Deore XT Trekking SL-T780 10 speed shifter, which I used many years ago on the Polygon Cozmic MTB.
Upon installation of the rear derailleur to the bike, I found that there was quite a bit of friction from the clutch unit, even though the clutch was turned off. Therefore, I opened up the clutch to take a look. Here is how you can service your clutch too!
How it looks with the internal clutch unit removed from the rear derailleur.
Here is the clutch unit. It can be serviced or replaced if it is faulty.
Then, I realized that the rear derailleur will function perfectly fine without the clutch unit. As I don't need the clutch function, I decided to just remove the clutch unit, allowing the rear derailleur cage to swing smoothly, and also reducing the shifting force.
Once the 10 speed shifter has been installed onto the bike, along with the other 10 speed components, I took the bike for a test ride!
A derailleur drivetrain looks good on the bike!
Lots of ground and tire clearance, due to the super short cage Saint rear derailleur.
The whole bike looks good in the sun. Purple and yellow colour combination is weird but really outstanding.
Went to the same step that caught the R7000 rear derailleur previously. No issue this time!
Good clearance for the rear derailleur cage.
The optical gear display on the shifter is good as well, due to the clearly defined gear indication.
Can clearly see which gear I am currently in, and how many more available on either end.
Based on the test ride, this 10 speed setup has passed with flying colours! However, I also need to check how well it works when it is folded. Due to the short cage, it is expected that the chain would become even more slack when the rear triangle is folded down.
When folded, the short cage barely takes up any slack chain.
Due to this, the chain becomes way too slack, as the chain is long enough to touch the ground already.
As the chain is way too slack when folded, it will touch the ground, which is not acceptable for me. Also, due to the short engagement between the chain and cassette when folded, the chain is likely to drop off the cassette when the bike is unfolded again.
Therefore, even though this 10 speed drivetrain rides really well, it is not good enough due to the poor chain management. I need to keep trying alternative ideas that will work better.
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