46/30 with braze-on FD?

I think 46/30 cranksets have been pretty popular in the gravel community, and is what I've decided to use as well after spending hours with the gear ratio calculators. Should I be concerned at all about the FD not going physically low enough with a braze-on frame? 

Granted I'm not planning on a 46/30, but I am planning something a bit drastic on a Trek Boone. I'm hoping that the braze-on doesn't become an issue. My experiences so far might be helpful. I have a 38/28 Ultegra set up 2x10 from a triple. I used the Shimano CX70 FD (clamp) and it works great. The bottom of the seat-tube flairs near the bb on the Redline, so it limits how low the FD clamp can be set, yet it works. My plan is to transfer this set up to the Trek using a braze-on CX70 FD. Preliminary measurements look ok, but until it's all installed and shifting, I won't know for sure. I thought the Wick Werks fit link for juniors would be an option, but it put the FD too low and the cage hits the chainstay and can't be adjusted higher. Factors are; braze-on distance from BB, chainstay height, FD cage angle (IRD FD cage hits chainstay and would have to be raised too far out of workable range), and the frame you're using. In short, the braze-on poses challenges that the clamp FD didn't. My guess is that since you're going 46/30 getting the FD low enough won't be a problem for the 46, it's the 30 that will have to be finessed. Once I get the bike to & back from my LBS, I'll post the results.

I would expect it to still work, but if it doesn't Wickwerks makes an adaptor to mount the derailleur lower.

 

Thanks! Came across that earlier, hopefully it'll get me out of a jam if needed.

Before you shell out for the fit link note that WickWerks states that it is designed for 41/33.

If you want to get really funky you could probably use a JTek Shiftmate and a mountain bike front derailleur in combination with those chainrings and the WickWerks adapter.  Lots of things in the system mean lots of things can go wrong, but then in theory you could use road shifters with a mtn FD and mountain chainrings on a braze-on frame withouth hitting the chainstays.... wow, that is a mouthful!

@crossbones Thanks for pointing that out. I was under the impression that let the FD slide up down like the mount on the frame, but maybe not.

@clarksonxc Thanks, but I'd like to switch to Di2. Also I think 46/30 is probably too big from mtb FD's?

Hmmm, good point.  I am not sure about the electronic pull ratios (lol) and basic cross compatibility.  Sounds like a Leonard Zinn question!

Hope your 46/30 turned out the way you wanted. The excellent mechanic at the Trek shop got my 38/28 to work with the CX70 FD on the Boone braze-on. So far no issues.

Thanks for the feedback. The parts have been sitting in my closet for a few weeks now, hopefully they'll make their way onto the bike sooner than later. The current fd has quite a bit of room to go lower on the mount with the 50/34 so I'm hopefully the 46/30 will be ok.

I've pieced together some odd combos. Typically my bigger challenge is making sure the tail (rear) of the FD cage clears the chainstay. This typically means the gap between the outer ring and the cage is a bit larger than desired. The CX70 is a great option if it will work for you due to the shorter length of the cage. This allows it to be positioned lower on the seat tube.  

Di2 is pretty remarkable in dealing with a host of odd and wide combos ; )