Tuning The Ride: 29″ers and Steering Performance Part III
January 8th, 2008 by Guitar TedEditors Note: This is the third and final installment of this series. However; it is not the end of the story. We’ll be focusing in on different aspects and theories concerning 29″er geometry throughout 2008
One of the things I mentioned on Twenty Nine Inches in a different post concerned the seemingly divergent paths that the designers of 29″er bikes and forks are pursuing. I’ve also seen it mentioned in recent comments. This post will explore a bit of those concepts to perhaps get a clearer picture of what is going on.
One of the paths that designers have been pursuing over the last few years is a way to get 29″ers to feel more “26″er-ish”. This mostly has to do with getting away from the feeling that a 29″er sometimes has of requiring more input to initiate turn in and to overcome the 29″ers natural tendency to want to stay on its path as it spins, or in other words, its gyroscopic tendencies. Combined with a larger trail figure, this can be felt as a “sluggish” feeling in some riders minds. Various types of designs have attempted to address this trait of big wheels to various degrees. The flagship design of this type of philosophy in my opinion is the G2 29″er geometry that Gary Fisher Bikes has offered on its 2008 line of 29″ers. It excells in being a design that 26″er devotees can hop aboard and feel right at home on. Still possessing 29″ers abilities to roll over stuff and carry momentum easier, it has erased the “heavy” feeling some associate with 29″ers.
Interestingly, some refer to the Fishers and similar bikes as “new school” geometry. I think, if anything, it should be called “old school” geometry because most of these bikes are trying to emulate the “old” 26″er steering feel. Not a bad thing, but in no way is this a “new” thing. Whatever you call it, it is a definite trend and I expect it to expand with the passing of time.
There still is a contingent out there that celebrates the 29″er wheels stability and steering quirks as being the very thing that differentiates 29″ers from 26″ers in the first place. This design philosophy was best demonstrated to me by this LenzSport Lunchbox 29″er. It has dual suspension and longer travel, and that certainly factors into things, but the trail figure on this bike was off the charts high compared to anything I had yet ridden. Still, it behaved quite well on the trail and imparted a sense of security that inspired me to want to tackle bigger hits and attain more speed while doing so. I think the enhancement of the 29″ers inherent traits made me feel these things as much as the longer travel did, if not more so. (Special mention for a bike like this would also go to the Raleigh XXIX+G with stock geometry. We’ll be testing this bike in that form again soon.)
Most 29″ers out there today are somewhere in the middle of this “handling continuum”. Being able to tune the handling to go towards one end of this continuum or the other is a trick that we didn’t have only just a year ago. What a great time to be riding big wheels!
Look for “updates” to this story over the course of 2008 as Twenty Nine Inches seeks to discover just how all this geometry works out on the trail.
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I still say, if you like the ride of a 26er, ride a 26er, I got a 29er to have something different, because I was tired/bored of 26ers
The thing that I think draws people to 29ers, especially after they ride one, is that they are easy to ride. The very essence of what makes a 29er different from a 26er is its swoopy steering. By swoopy, I mean that it is easy to get into this kind of gliding rhythm as you negotiate turns and curves in the trail. The handling feels very natural and inspires confidence.
I like to think that the 29er is the hawk in the sky - gliding along, cruising, but when it needs to, it can make a quick turn and nail its meal. The 26er is the blue jay that zips back and forth (and may eventually get eaten by the hawk
).
I just tried out my new On - One. It’s a small size frame so only 71 head angle with 47mm offset
A while back I had a medium Fisher 29er from the first or second year of production.
The On - One handles pretty much the same as my steel 26″ hardtail but still rolls over stuff with ease. It’s like a magic carpet ride.
I can’t feel it struggle through soggy grass uphill, and downhill it smoothes out a lot of small trail irregularities
Even though it has no suspension it’s another notch along the evolutionary path……
[Pah! to flat earth creationists]
Jeremy, you bike then is identical to my Redline Flight, on paper. Just I get the top tube I need with the XL frame. Really natural and never overly nervous or slow, don’t you think? The larger On-One’s really got this geometry because we at the time felt that 26″ riders would need something extreme to be convinced. So it was not intended as the ideal 29″ bike, rather than something that would impress on the short term, and that it did. Today, I cannot come up with much better figures than Gary worked out, by TESTING geometries. Don’t yáll underestimate this factor, hardly ever is geometry actually testing in various setup before deciding on a set of figures. Designers like to think they know it all, and don’t need testing. I’m like that even, and will stay so until I get access to resources to test multiple versions of a proto frame. It never went past 1 proto, really.
Mike, the way you describe 29″ seems like how someone would want a bike. If one wants to ride rodeo, buy a mechanical bull, not a 26″ bike. Want to ride XC, get a bike that does cross the country, in fluent lines.
I like Mike’s description - it paints a portrait of what I feel is the difference between my 26″ and 29″ bikes. Great description.
GT - thanks for tackling this. Your objective, laymans approach is always appreciated.
Mike: That was beautiful! (wiping back tears)
:)
Thanks for the write up, I have been planning a new custom fork for my Vicious and your explanations have reinforced my decisions. Slacken the head angle and increase the offset. I am hoping the longer wheelbase will be good too.
Thanks for the write up, I have been planning a new custom fork for my Vicious and your explanations have reinforced my decisions. Slacken the head angle and increase the offset. I am hoping the longer wheelbase will be good too.
I’ve said this elsewhere but it’s more relevent here.
I chose this particular geometry over say a Singular Swift [UK 29er web based co] due to the fact that I can go either way with a sus fork.
From 71 head 47offset and 470 fork
I can go 80mm travel 490mm sus fork with 44mm offset without hopefully too much of a change
On the other hand if and when the G2 geometry forks become available I can buy a 100mm fork, use the smoothie head set with the deeper base cup [+5mm] and end up with the head angle within a smidgeon of sagged Fisher G2. Even the BB measurement shouldn’t be more than 5-7mm out as the Fishers seem to run a highish BB.
Of course readers will know I’m anything but an expert, and weight distribution may make the bike handle differently, but I think it should work, close enough to take a risk.
Niner and Singular have used a long rigid fork so that buyers can switch to a short offset sus fork [all that was available], steepen the head angle, and still get good handling results
The new forks may allow a change in their thinking.
How far are we from eccentric head tubes? Change the HT angle on the fly depending on trail use.
Anonymous: been there. See Mongoose’s “Front Porch” and early American mtb’s from the 80’s
G-T: 1985 to be precise http://www.firstflightbikes.com/1985_American_Montaneus.htm
I’m loving the quicker handling and nimbleness of my Superfly, that was my main gripe with my Supercaliber and Paragon. Felt like you needed and act of congress to get thru a sharp turn. Not anymore, the new g2 stuff is has brought it back around.