Researched & Ordered new derailleurs
Ordered new front and rear derailleurs and chain.We went for a long ride to Macquarie Rivulet (35km) and on the way back the chain snapped. This was despite having changed back to the 3.5mm spacers and feeling everything was running fine. I had taken a "quick-link" and chain-breaker so we got home no problems.
I then spent a few hours researching derailleurs and almost bought a 10 speed rear derailleur (which had a clutch mechanism on the tensioning wheel) but luckily found it would not work as it requires a different pull ratio so I would need new shifters and as the 10 speed road shifters used the same pull as the 9 speed I had that would not work. Also new shifter or levers were VERY expensive.
So my current 9 speed shifter pulls 2.5mm of cable and the derailleur converts that at a ratio of 1: 1.7 (so 1.7 x 2.5 = 4.25) so this is not exactly correct as the 9 speed cassette has a pitch of 4.35mm, but it is close. The pitch on the 10 speed cassette is 3.95mm so it will pull too far.
So I ordered a 9 speed rear derailleur.
I also researched whether I could use a medium cage derailleur.
The medium suits up to 33 tooth variation while the long arm copes with 45 tooth, that is the longer arm can maintain tension on a lot of extra chain.
So it is the difference between the largest front, largest rear and the smallest front, smallest rear (i.e. cross chained both ways but you don't want to run out of tension. So if we call 54 + 34 = 88 then when we change to the smallest we are at 39 + 11 = 50 so we have a difference of 38. That is the derailleur needs to keep 38 links taught. So we definitely need the longer cage.
I also decided to order a new front derailleur.
My current one is a FD6600
I couldn't find an FD6600 so I ordered an FD6700 which is a 10 speed version which apparently works fine even though it is designed for narrower chain.
As I understand the FD stands for Front Derailleur and the 6 is the quality so in this case Ultegra and the next number stands for the model while the 00 is standard. If it was a variation it might have a different last number.
Finally I researched chain length and I think I have made the chain just a fraction shorter than recommended.
This shows the chain on the largest front and rear sprockets (54-34) and the chain split at the "quick-link" and it is recommended to have 1 link or 2 chain segments extra. I was just unable to get the pins to line up with 2 extra segments so I think I will lengthen the chain.
I then spent a few hours researching derailleurs and almost bought a 10 speed rear derailleur (which had a clutch mechanism on the tensioning wheel) but luckily found it would not work as it requires a different pull ratio so I would need new shifters and as the 10 speed road shifters used the same pull as the 9 speed I had that would not work. Also new shifter or levers were VERY expensive.
So my current 9 speed shifter pulls 2.5mm of cable and the derailleur converts that at a ratio of 1: 1.7 (so 1.7 x 2.5 = 4.25) so this is not exactly correct as the 9 speed cassette has a pitch of 4.35mm, but it is close. The pitch on the 10 speed cassette is 3.95mm so it will pull too far.
So I ordered a 9 speed rear derailleur.
I also researched whether I could use a medium cage derailleur.
The medium suits up to 33 tooth variation while the long arm copes with 45 tooth, that is the longer arm can maintain tension on a lot of extra chain.
So it is the difference between the largest front, largest rear and the smallest front, smallest rear (i.e. cross chained both ways but you don't want to run out of tension. So if we call 54 + 34 = 88 then when we change to the smallest we are at 39 + 11 = 50 so we have a difference of 38. That is the derailleur needs to keep 38 links taught. So we definitely need the longer cage.
I also decided to order a new front derailleur.
My current one is a FD6600
I couldn't find an FD6600 so I ordered an FD6700 which is a 10 speed version which apparently works fine even though it is designed for narrower chain.
As I understand the FD stands for Front Derailleur and the 6 is the quality so in this case Ultegra and the next number stands for the model while the 00 is standard. If it was a variation it might have a different last number.
Finally I researched chain length and I think I have made the chain just a fraction shorter than recommended.
This shows the chain on the largest front and rear sprockets (54-34) and the chain split at the "quick-link" and it is recommended to have 1 link or 2 chain segments extra. I was just unable to get the pins to line up with 2 extra segments so I think I will lengthen the chain.