This is a pre-Y2K bike so I'm calling it semi-vintage.
Original setup (OEM):
- 12-25 Cassette (9s) on RD-5503-GS (Shimano 105 9s triple medium cage)
- 52-42-30 Triple Rings (130/74) FC-5503 with FD-5503 (Shimano 105 9s)
- ST-550X? - 3x9 Shimano 105 STIs
I needed new chainrings. I had the classic chainring slippage/disengagement under load when I tried a new chain so it was off to do some research. This is my "adventure" bike (650b conversion) so a little lower gearing would be alright in my book. Over in the 650b Google Group there was a long gearing discussion on these types of bikes. I was originally planning on 46/30 with an 11-34 or 11-36 cassette, but reading numerous posts from others steered me towards 44/28 with 11-32. This was going to be set up as a 1x-bailout, riding the 44t in the middle position with the best chainline most of the time. Bailout to the 28t when needed (only for lowest 2-3 gears).
Per Peter White's TA Chainring page, the TA inner rings may not work on the 74 BCD spider of other brands. So I didn't want to pay a premium and have something not work. I ordered some cheaper Spa Cycles rings:
So I finally got around to installing the rings. Since I ordered the tabs to go on the outside, the old bolts (for a ring on each side of the 130 BCD spider) worked fine. Shifting with the triple front derailleur left much to be desired. It wasn't impossible to get it to shift, but if it's struggling on the stand it usually doesn't get better when you're in the saddle. Also the channels or grooves in the triple front derailleur didn't really align, so even when I got it semi-workable it rubbed in all but a couple gears, so I couldn't use it as a 1x-bailout as planned. I tried moving it up, down, toe-in, toe-out, parallel - nothing got it to work better. The best was actually leaving it around the normal position, and faking it almost as a low-middle setup only. The other issue with the triple was getting the high limit set - even with the screw fully threaded in, it was still at bit too far outboard.
After reading several threads on the Shimano FD-CX70 front derailleur, I went ahead and found one (thanks to the sales group here). It worked a charm with the rings and 9s STI. Other anecdotal evidence suggested using a 10s chain, so I went ahead and fitted one (never tried the 9s) as I wanted to get the full range out of the middle ring for my 1x-bailout setup, and I figured the wider 9s would be more likely to rub.
It didn't take too long to get it dialed in, and I'm very happy with the results. Shifting is good, not as crisp as the OEM setup but it's good. The middle ring from Spa has ramps/pins - I'm not sure if they're aligned quite right or not for great shifting, but it does work well enough for my use. It uses clicks 1-4 of the triple shifter (trimming on each small and middle) and the 5th click is locked out by the high limit screw.
For the rear, the triple derailleur clears the 32 cog, but I do have the rear pulled all the way back in the dropouts (removed the adjusters). Technically I'm right at the max capacity of the GS but it works without any issues.
For the gearing, the 44/11 is good enough for my use, especially given the "adventure" nature of this bike for me. Given I had a 52/12, it's only about 8% lower gearing. On the low end, on my first decent ride, I found myself in the 1:1 (28-28) once, so it was nice to know I had one more gear if I needed it.
Hope this helps anyone in a similar situation. Reach out if you have any other questions, I've glossed over a lot of details. Take care and stay safe everyone.
