Added a comment about feature Modern Mountain Bike Geometry Defined - Transition Explains Effective Top Tube Versus Reach 7/11/2017 3:31 PM

I measured the down tube on both bikes, and they are in fact discrepant; however, I spoke with the manufacturer, and the rep assured me that down tube length is nothing to investigate as a possible source of my discomfort while standing on the smaller bike. It seems odd though that the two bikes (the way I have them configured) are nearly identical, except for down tube length. The bike with shorter DT length = terrible weight distribution in standing position. The bike with longer down tube length = engaged core/weight on legs in standing position.

0 0 0

This feature has 39 comments.

Added a comment about feature Modern Mountain Bike Geometry Defined - Transition Explains Effective Top Tube Versus Reach 7/11/2017 9:01 AM

Yep, I forgot a critical part of the equation: bar rise. One of the main limitations for me on the 18.5 is cornering confidence. On the 17.5, I have great confidence in the turns, while on the 18.5, I get real timid, as I can feel the front wheel wanting to get out from under me (less so since I started scrutinizing my technique but still to what I believe is an excessive degree). I run the same 27 mm riser bar (720 width) on both bikes, and I know that 27mm is probably quite a drastic rise on a XC bike. The stock bars resulted in neck and back discomfort on BOTH bikes, and I read that these symptoms often stem from bars being too low; thus, I experimented with the riser bar. I know that bar height can make the front wheel light, and my present bar rise might explain why the front tire wants to wash out on the 18.5; however, here's the tricky part: I still don't understand which discrepant variable(s) might account for back and neck pain on the 17.5, given the fact that my data gathering employed the same riser bar on both bikes. Riser bar + 17.5 = wrecked back and neck. Same riser bar + 18.5 = engaged core and little to no back/neck discomfort. The stack between the two bikes is different by 1mm, and I played with spacers to offset this difference on the smaller bike, but achieved no desired results.

My height = 5' 8.5" shoes off

Inseam = 31.5" shoes off

0 0 0

This feature has 39 comments.

Added a comment about feature Modern Mountain Bike Geometry Defined - Transition Explains Effective Top Tube Versus Reach 7/11/2017 6:30 AM

NIce article. I've read every comment here, and I have a riddle that may relate to General's and Big Bird's assertions re: downtube length. Here goes: I've got BOTH a Superfly 17.5 AND a Superfly 18.5. I've set them up so that the reach is exactly the same on both bikes. The 17.5 (with stock stem) wrecks my back and neck, and I believe this back and neck discomfort results, at least in part, from the standing position; when I stand on this bike, I can't seem to get my body situated so that my legs support my weight. Rather, I can feel the strain on my back almost instantly. A few rides, and I'm done for a week or more and my posture is wrecked for a day or two. On the other hand, when I ride the 18.5 in the standing position, my legs support my weight, and I can feel that my core is far more engaged on this bike. The problem? I have to run a 65mm stem (25mm shorter than stock) on the 18.5 to achieve a manageable reach to the bars, which wildly compromises the bike's performance. So, I hypothesize that some variable/measurement discrepancy between these two bikes might elucidate why I can't seem to ride the 17.5, even though the reach is perfect right out of the box. If I'm understanding General's and Big Bird's comments, could DT length shed some light on my dilemma? If so, what can I glean from this understanding so as to, moving forward, find a bike that both performs like it's designed to AND allows my legs to support my weight in the standing position? I know this article is geared towards trail-oriented geos, while the Superfly is XC, but I thought this discussion might still be a good place to discover how I might find a different bike (I'm thinking of switching to a trail bike) that works for me.

0 0 0

This feature has 39 comments.