I got my cross bike fitted recently. The fitter strongly recommended on switching from 160mm cranks to 145mm. I am looking for a new crankset. Getting cranks in that length would make the gearing about 10% more difficult. I would prefer one with a smaller BCD, so I can run smaller chainring(s).
One option I’m interested in is the Origin8 Triple Crankset, which is advertised as having a 46.5 chainline. I’m thinking about running the 39/30 cranksets from Shimano 105 5703, and not using the 50 tooth chainring. Based on the images I provided, do you think it would work with my 105 R7000 Front Derailleur? My current chainring combination is 44/34. I know that people use this front derailleur with 46/30. I’m hoping it will work with 39, though I’m aware 39 is a lot smaller than 44.
If this option doesn’t work, I’m thinking about going 1x. I know that there are more options with 1x. If I went with the Origin8 triple crankset, I’m assuming it would work well as a 1x if I mount the chainring in the middle?
If I go 1x, I will probably get an 11 speed GRX cassette and derailleur to maintain the low gearing. I’ll do this if it works best. I’m hoping that the 39/30 option will work to keep costs down. Let me know what you think.
by BigglyPigglyWiggly
5 Comments
You can buy a braze on height extender to mount your front derailleur lower.
https://ae-pic-a1.aliexpress-media.com/kf/S17cda52b1ad5463e9b2317fc7e6a2a694.jpeg_640x640q75.jpeg_.avif
145 is insane to me
Go watch Path Less Pedalled on youtube, Russ is the king of low gearing setups.
Lowering your front derailleur to 1-3mm above the 39 is probably too low in general, likely hitting the chainstay. It’s probably okay to have it sit a bit higher from the 39, say 5-10mm or more. If using a triple crankset, keep the large chainring or replace it with a guard.
Switching to 1x is probably the better but more expensive option. A grx rd-rx822 gs or sgs with a 46 or even 51 tooth gets you the lower gearing you need. I’m not usually an advocate for 1x, but I think it makes sense in your case.
145? Do you have hip mobility problems?