Originally Posted by
Turnin_Wrenches
I wasn't saying that more reach is inherently bad. My main point was that adding 17mm of reach to a position that is already comfortable is a really big move. And if the OP finds out post-purchase that 390mm of reach is too long, you can't make the bike "smaller". Final result = a bike that is to long and uncomfortable to ride. The only available "remedy" for this scenario (which isn't a remedy at all) would be a super short stem, handlebars / hoods that are rotated up and back too far towards the rider, and a saddle that is slammed all the way forward, all of which present new challenges and lead to a whole new set of problems that ultimately cannot be solved.
I deal with people every day who purchased bikes (usually from other shops) that don't fit. For reasons that I do not understand, they proceed (without hesitation) to spend several hundred dollars swapping saddles, stems, and requesting a multitude of adjustments in search of comfort because they refuse to accept the fact that they bought a bike that doesn't fit. Whereas, if they had spent $150-$300 dollars with a competent bike-fit professional (before purchasing the new bike) they would have ended up with a bike they can comfortably ride and they would have saved money.
Why would the stem be super short? Does the OP's current bike use an already short stem?
The difference in top tube length between the two bikes is 11mm. That's because stack ignores the slope of the headtube, which makes reach 3mm shorter for every 10mm gain in stack. So a 20mm shorter stack bike (or just moving your stem down 20mm) makes the reach 6mm longer. At that point you only need a stem that is 1cm shorter to duplicate the same horizontal distance from the seat post. So you go from a 110mm stem on one bike to a 100mm stem on the new bike. How is that a problem?
I'm not saying that the OP's new bike idea will fit him fine. He should look into a fit. But there is no reason it couldn't be made to fit. He can also use a -17 degree stem or removed spacers to simulate the fit of a lower stack height. Or, he can use 20mm of spacers and one size smaller stem on the new bike to put himself in the identical position to the old one. Unless you ask for the steerer tube to be chopped, most production bikes come with 40mm of steerer tube height that the stem can be moved up and down in. You are reacting to the OP as if he's got a currently slammed stem and is going to another bike with a slammed stem. But both probably have a good amount of adjustability in an overlapping range that would allow for identical fit, if going lower doesn't work out.