An Experiment In Front End Geometry: The Baseline

In this post I will detail the “baseline” for the handling characteristics that all other comparisons will be measured against. Keep in mind that this is my opinion. Your “baseline” for handling may differ from mine, but we all need a reference point here, so this is it.

OS Bikes Blackbuck/On One Carbon Superlight fork

The OS Bikes Blackuck has been set up like this with the On One Carbon Superlight fork for most of the year so far. Here are the pertinent numbers for you to crunch on:

Head Angle- 72 degrees
Axle to Crown- 470mm
Offset- 47mm
Wheelbase- 42.8″
Bottom Bracket Drop Range (EBB) 53.4mm-63.4mm
Approximate Trail*– 76mm

Handling Characteristics: The On One fork and Blackbuck bike are like an old friend to me, reminiscent of the sort of handling I had with this same fork and the On One Inbred. That being quick, but not twitchy. Corners are carved with no drama. Slow speed maneuverings are perhaps a bit nervous, but imminently manageable. I find it best for medium to fast singletrack riding where carving a precise line all the way through a corner is important. Mid corner corrections are easy to initiate and complete without losing control.

A Note On The Forks Ride I have reiewed this fork on Twenty Nine Inches, (Please check in the Search box at the upper right of the page for more.), so I will not go into too much detail here other than to say that this fork rides very nicely, is tough, and gives your brakes a slight boost in performance due to the excellently designed drop outs.

OS Bikes Blackbuck/Blackbuck rigid fork

Next I will detail the changes made and the ride characteristics that resulted from switching out to the Blackbuck rigid steel fork with 440mm axle to crown and 51mm offset. Stay tuned….

*The trail charts I used all gave slightly different answers and of course, your tire selection will also affect the trail figure slightly. Take my trail figures with a grain of salt. Your mileage may vary!


No Responses to “An Experiment In Front End Geometry: The Baseline”

  1. Steve Says:

    An adjustable rake and adjustable axle-to-crown fork would be perfect for this experiment. Wouldn’t be too hard to do, with sliding dropouts…

  2. Mike Says:

    With the different height forks, are you going to maintain a consistent saddle position (set back) relative to the bottom bracket?

  3. jeremy uk Says:

    There are other apparently significant factors in handling such as front centre and seat position [seat angle isn’t really al that helpful since one can move the saddle on the rails]

  4. Dan Says:

    My experience, I own a 440 Pace 26″ wheeled fork that cleared a 29″ tire. I have been running it on my Carver 96er. I wanted a little more slack so I replaced the existing Chris King crown race with one 5mm higher. The bike rides great and I can use the fork on my other 26″ bike if I want to. BTW you can get race crowns for CK head sets that range from 4mm to 7mm. CK makes them in 5mm and Ventana makes them in 4mm and 7mm. This is a very light set up.

  5. Guitar Ted Says:

    Steve: That has been done on a 29″er already. Walt Wehner of Waltworks bicycles did just what you are talking about. His conclusions were that the current range of offsets were most ideal for a wide range of riders/.conditions. Although there were some interesting points that he made concerning “getting used to” a bike set up that I will also bring up.

    Mike: Yes, I have made a point to keep my saddle relationship to the bottom bracket constant as well as my saddle to bar relationship. I will divulge changes in regards to this with each fork swap.

    jeremy uk: See my response to Mike above. 🙂

    Dan: I also am aware of the Chris King crowns and I have a 5mm one that I am going to make use of on a fork swap soon.

  6. FJ Says:

    Walt of Waltworks fame had a steel fork early on that had slotted dropouts, like a singlespeed dropout, so offset could be changed very easily. Perhaps such a fork would be extremely valuable in today’s 29er market?

  7. Willie Says:

    GT-I would find it helpful if you would include the “trail” figures for each set-up. This would make the multiple fork set-up easier to compare. Thanks.

  8. Mike Says:

    GT – I can’t find your e-mail address, drop me a line and I’ll send you a spread sheet that will calculate trail that I found on-line.

  9. Willie Says:

    GT: Could you please include “trail” figures for your different set ups. This would make quick comparisions between the different set ups easier. Thanks.

  10. Desert9r Says:

    Does anyone know where to get a 440/445 a-c fork for less $ than the WB Rock Solid?

  11. Guitar Ted Says:

    Mike: Thanks! 🙂

    Willie: I’ll get that up soon for all to see.

    Desert9r: Have you checked the Origin 8 one? It might be what you are looking for. I think the 26″er fork clears a 29″er tire just fine, but it is a bit shorter axle to crown than what you are thinking, if memory serves correct. Anyway, there are also some on flea-bay from the same factory as the White brothers forks. Might be worth a looksee.

  12. Mike Says:

    Also check out Vicious (438) and Salsa CroMoto 445.

  13. Cloxxki Says:

    Surly and Zion have forks in that range too. Don’t be put off by 26″ V-brake studs, they won’t get in the way.

  14. Dirt McGirt Says:

    I didn’t see the atmospheric conditions listed during the measuring process…

    We need to be thorough, GT.
    Come on, now.

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