Hi, Sort of nerdy mechanic question. I was wondering if there are any reasons not to try combining Shimano chainrings in combinations other than how they are sold. (For Dura Ace 9100 and Ultegra 8000)
They come in: 53/39, 52/36, 50/34, 46/36 CX, and then the rare combos with chainrings larger than 53... I know that the gap limit between rings is 14-16 teeth depending on which combination. I know that Ultegra 6800 also had a 38 tooth inner ring replacement option (rare and hard to track down).
If I wanted to make combos other than these – such as 52/39, 50/36, 50/39, 46/34 – is there any reason why they wouldn't work well? Is the ramping on the inside of the large rings optimized to work with an inner ring of a pre-set size? I'm partly wondering about a 46-34 combo as an option when changing gearing on an all-road bike between a more paved road setup vs. a more gravelly setup (and yes, I know there's GRX cranks with even lower gearing, but not quite the same bolt pattern, Q-factor, or chainline, and needing the GRX front derailleur). Also wondering about different tri builds where a 1x isn't quite enough, but the 34 feels too low when paired with a 50.
I assume that "They will work fine" is a likely answer, but I'm wondering if people know about "optimal" shifting and design or have experience, and there's nowhere else better to ask than here on Slowtwitch! Thanks!
They come in: 53/39, 52/36, 50/34, 46/36 CX, and then the rare combos with chainrings larger than 53... I know that the gap limit between rings is 14-16 teeth depending on which combination. I know that Ultegra 6800 also had a 38 tooth inner ring replacement option (rare and hard to track down).
If I wanted to make combos other than these – such as 52/39, 50/36, 50/39, 46/34 – is there any reason why they wouldn't work well? Is the ramping on the inside of the large rings optimized to work with an inner ring of a pre-set size? I'm partly wondering about a 46-34 combo as an option when changing gearing on an all-road bike between a more paved road setup vs. a more gravelly setup (and yes, I know there's GRX cranks with even lower gearing, but not quite the same bolt pattern, Q-factor, or chainline, and needing the GRX front derailleur). Also wondering about different tri builds where a 1x isn't quite enough, but the 34 feels too low when paired with a 50.
I assume that "They will work fine" is a likely answer, but I'm wondering if people know about "optimal" shifting and design or have experience, and there's nowhere else better to ask than here on Slowtwitch! Thanks!