An Experiment In Front End Geometry: Final Thoughts

The long journey has finally come to a close. The “Experiment In Front End Geometry” series was a lot of fun. I got a lot of positive feedback on this, and I think we all learned a few things along the way.

Sick of this bike yet?

I have to give credit to OS Bikes for making such a fun machine to do this test with. The bike was a hoot, but I’ll post some final thoughts on it in a separate post. In all, I tested eight different forks on the Blackbuck throughout the duration of this test. The bike never flinched, although I did a couple of times!

Muddy Blackbuck

When this test began I never thought I would really like anything other than the On One CabonSuperlight fork that I had on it when I started this testing. I can honestly say that there were some forks that I tried that I could have lived with for a long, long time. There were a couple I just didn’t prefer, but in the end I found out something that I thought perhaps would show through before all of this testing began.

Lenz Lunchbox

It all started after the 2007 Interbike trade show where I rode this bike belonging to Mike Curiak. The geometry was not known to me at the time I rode the bike, but when I found out after the fact what it was, I was astounded. How could a bike with such slack angles and high trail figure handle so well? Maybe numbers weren’t all they were cracked up to be? How could geometry lie though?

Through some e-mails traded back and forth with Mike, I came to a vague understanding that 29 inch wheels were to blame. Yes, the wheel size lets you defy science……well, not really! It would be more accurate to say that the dynamics of the wheel trump the geometry a bit. That is to say, the gyroscopic effect of 29″er wheels allows for things to happen in conjunction with geometry that can not happen with smaller wheel sizes. For one thing, a wider range of fork/front end geometries “works” than with smaller wheeled brethren.

For instance, I was running axle to crown heights anywhere from 430mm to over 500mm and all were rideable on the same frame. I was using these forks with offsets from 38mm to 51mm and all were rideable, which shows that a wide range of fork geometries is acceptable on a 29″er. It may not be your preferance depending upon the specific set up, but the front ends of 29″ers can definitely be tuned to a preferance. The window of opportunity to do that with smaller wheels is much more limited.

So, numbers do not necessarily mean what they did on 26″ers. In fact, you can throw out everything you knew about 26″er geometries, because 29″ers are a whole different ball game. If there is only one thing you take away from any of this, let it be that 29″ers need there own set of parameters. Not only in terms of front end geometry, but in every component made for the big wheeled bikes.

Following are the links to all of the posts relating to this series for quick reference.

Introduction
The Baseline Fork
Fork #1
Fork #2
Fork #3
Fork #4
Suspension Fork #1
Suspension Fork #2
Suspension Fork #3

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No Responses to “An Experiment In Front End Geometry: Final Thoughts”

  1. plesurnpain Says:

    GT
    Thanks for putting in all the long ours in the saddle needed for this experiment. This must have made for some long days at the office! I couldn’t agree with you more about the numbers not being the final word in handling. I personally don’t even run trail numbers (anymore), it just makes me think to much (which is never a good thing). I used to over think things like this now I just look at A/C and offset numbers for coparison purposes. All of your research leads me to believe that maybe I’m on to something. It’s been fun watching your transformation in thinking through tis process as well. Keep up the good work and as always smile while you ride.
    PS-As I mentioned in an email, I’m looking to go carbon for my XXIX. I’m leaning toward the Exotic in the 445mm. It may be a while before this happens, but I’ll give you an update when it does. If you have any thoughts or suggestions i’d love to hear them.

  2. BunE Says:

    I did the Exotic at 445mm on a monocog and so far I am loving it.

  3. Davidcopperfield Says:

    Fine work for sure. since the trail&manouevrability changes why not try Hi-fi pro with 38 and 44-46mm offsets?
    Why not try other FS 29ers with 51mm offseted forks? Those would add more into the mix.
    Good Luck

  4. plesurnpain Says:

    Thanks BunE. I’m lookinf forward to picking one up and trying it out. It will probably be a while, the snow is about to fly here. Soon I’ll be on skis.

  5. GreenLightGo Says:

    GT – this has been a great series of posts. Thanks for doing the leg work (pun intended) and debunking some of the myths.

    One question though – what will end up on the Blackbuck for the long run?

  6. Guitar Ted Says:

    GLG: Thanks, I appreciate the kind words.

    I think I’ll go back to a rigid fork. For my riding around here, it is all I need from a single speed standpoint. That said, the Spinner 2Nine will be there for a time, since we are testing it. Then the Blackbuck will more than likely return to either the On One fork, the rumored new G2 Switchblade, or Niners new carbon fork. (Hey! One can never try too many forks, right?) 🙂

  7. dan Says:

    Thanks for doing all the legwork, today’s options are way too complicated. Lots of sound advice. I have not near the time as you do on 29ers so I listen to your views which are spot on. I like rigid forks for handling and precision but like the shock absorbsion on suspension. Have you tried suspension stems? I’m currently running a salsa fork with a softride stem.
    And my next one is with a Bontrager fork. should be about 2 pounds or less with the trans x suspension stem. I’m 52 so it makes my body feel not beat up after a 4 hour ride. so far liking the set up . Happy trails.

  8. Guitar Ted Says:

    dan: Again, thanks for all the great comments and for following along.

    I used to ride with a suspension stem in the 90’s, but I never could get the hang of it in combination with 26″ wheels. Endo city! I bet a 29″er makes a big difference in the use of one of those.

    Ride On!

  9. Steve Says:

    GT,
    Had a good read of your research very enlightening.. One quick question….if I go from WB Rock Solid to On One carbon SL on the same frame, front wheel i.e. all the same save the fork. What are my expected handling differences? Am considering the change to go for bigger brake & greater longevity (have seen boken WB not On Ones). I realise that there is a AC differences (5mm) which of course will make a slight difference.

    Thanks for your time

    SP

  10. Guitar Ted Says:

    Steve: I’d expect a slight increase in steering quickness. You might notice that a very slight lean, or movement at the bars results in a greater response in your bike’s handling. It might show up in long descents where the bike might seem a tad bit more nervous/twitchy than before.

    Specifically in terms of the On One fork, I think you will notice a more solid feel in handling, braking will be much improved, and I think you’ll much prefer the On One overall. That is, if you get on with the handling performance it imparts, which I think you will.

    Thanks for reading and Ride On! 🙂

  11. Jcolflesh Says:

    Any word on when the Niner carbon fork will become available?

  12. Guitar Ted Says:

    Jcolflesh: As far as I know, sometime next year. Look for a release date to be given around Sea Otter time.

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