I must admit that I don’t follow bikes I would never buy that closely. So it totally escaped my notice that ENVE’s Custom Road frame uses a “rear-mount” brake caliper on the front fork. They aren’t the only bike OEM that does that. I first noticed it on the 3T Exploro; a bike a friend owns, that I have occasionally worked on. Unfortunately, I don’t have a great answer there. I’ve seen some claims that it’s easier to manufacture, and therefore cheaper… for the OEM, not you, you have to buy a different brake caliper, or maybe, just a different mount to change from the kind that bolts into the frame, to the type that bolts through the frame. Interestingly, ENVE also seems to have moved away from this design in their subsequent framesets.

I’ve also seen claims that it reduces the chance for damage to the fork, because you can’t cross-thread an expensive fork. OK, that’s true, you can’t cross-thread the fork if you aren’t bolting anything into the fork. But, that seems a bit thin. How often are you removing and reinstalling a front brake caliper? And, I guess more importantly, how many ENVE frameset buyers are working on their own bikes ;P.

That doesn’t mean I don’t have any answers, because when I recently posed this question on Ben Delany’s SRAM Red launch video. BTW, there’s a new SRAM Red. Little better than the old SRAM Red. Little lighter, more buttons (Yay!). But, still using the wonky direct mount PM+chainrings design (sorry, Ben, people do ruin chainrings, you clearly don’t spend enough time in r/bikewrench :P), still using DOT hydraulic fluid.

The next thing I have an answer for is whether Shimano road brake calipers are the same front and rear, or if it’s just the difference in what kind of mounting bracket comes on the caliper.

I’ve included some photos below of 9200 and 9100 front/rear brake calipers. It’s quite evident that they are not visibly the same. The front caliper has a cut-out for where the retention bolt goes into the fork.It might be possible to put a front caliper on a rear mounting bracket, dunno. I wouldn’t do that :).

Circled in red for visibility. Yes, I know it’s time to clean the Tarmac.

• DA 9200 rear:
  
• DA 9200 front:
  
• DA 9100 rear:
  
• DA 9100 rear: