Originally Posted by
gus6464
You're looking at this the wrong way. The enigma is meant to fit differently than the bike you already have. Higher stack with same reach means that you will be more upright on the enigma vs the Jamis. You need to decide if that's what you're actually looking for. Also the 54 isn't going to be more flexy just because it's one size smaller. You downsize if you want a racier position and upsize if you want more stable feeling bike.
it is interesting that you are saying that a smaller size will not be more flexy. Is this due to the fact that the tubes are shorter and this will compensate for thinner tube walls?
And regarding the difference between 54 and 56. Yes, 54 is racier but when you take into consideration the stem and spacers, you can easily achieve practically the same stack and reach on both frames. On 54 you have to use 30 mm of spacers and 100 mm stem (-6) and on 56, you use 10 mm of spacers and 90 mm stem (-6). This is based on this
Stack and reach calculator But does the same reach and stack does mean that those bikes will handle in a similar way? The smaller bike will be more agile as a rule, but the stem will be longer so it will slow the steering slightly, and the bigger frame will be less agile, but the shorter stem will make things a little bit quicker. In terms of compliance, the smaller frame should be better due to the fact that seat tube will be shorter and thus seatpost will be more exposed and at the front, there will be 30 mm of spacers making a little more room for fork steerer to flex whereas bigger frame will have only 10 mm spacer (less flex). What would you choose?