Gary Fisher HiFi Deluxe 29"er: The Technology of the Ride

Fox F 29 fork with Fisher's exclusive G2 offset

When we here at Twenty Nine Inches talk about the Fisher 2008 models we often mention how “G2 geometry” is changing the way 29″ers will be looked at, ridden, and made in the future. We rave on about the handling of this new set up. So…..just what is going on here anyway? Why would we seem to be all giddy about this new “geometry” and what does it mean?

Well, we could get into all the techy discussions about fork trail, offset, head angles and the like, but you and I both know that doesn’t really cross our minds when we are trying to cut that perfect line through the next root infested corner. Not that all the tech isn’t necessary or interesting, it is just gets in the way of what really matters sometimes. So, with that said, here is a very brief little description of just what is happening with G2.

The problem that has existed up until this point with 29″ers is twofold and both have something to do with steering. Problem #1: Going from a 26 inch wheel diameter to a 29 inch wheel diameter, assuming no other geometry changes, automatically makes for a slower steering bike due to increased “trail“. Trail figures that are high generally feel slower in terms of handling. Problem #2: 29″er wheels have a greater gyroscopic effect than a 26″er wheel. This means that a spinning 29″er wheel is harder to get to change direction than a spinning 26″er wheel is. (For a great visual on Problem #2, see this.)

G2 geometry was put together to help overcome these two problems with 29″ers. Of course, other companies have not been sleeping when it comes to these two basic complaints on big wheels. Let’s take a look at some of the existing solutions.

Head Angle: One of the earliest solutions was to simply increase the head angles of 29″ers to reduce the fork trail number and get back some of the quicker steering of a 26″er. Nothing else was really changed in terms of front end geometry from 26″ers. Typically a compromise of 72 degrees is used to accomplish this. It is a compromise in that it really doesn’t get you back to the snappy 26″er handling since you haven’t dealt with Problem #2 effectively. Also, it should be noted that many companies will only use this steeper head angle on their larger sizes to avoid toe overlap. Smaller sizes get stuck with a slacker angle. Sometimes an even steeper angle is used, but this is rare. Another issue could also be that the steeper angles don’t play well with teloscopic suspension fork designs due to the bump forces being transmitted into more fork flex.

Fork Offset: The next item up for review was the fork offset, which had been literally forged into suspension fork crowns at 38mm. This was an “ideal” measurement for 26″ers, but not so good for your big wheeled bikes. A compromise needed to be sorted out here, but with head tube angles still being worked out by 29″er companies, no fork manufacturer was really willing to go too far away from the old standard. Marzocchi and White Brothers went to 43mm with some middling results. This was a good step, but it still wasn’t solving either Problem #1 or #2. Something was needed that was “outside the box” and new in combination to set the 29″er handling free from the sluggish handling traits.

What Fisher has been able to accomplish is to wipe the slate clean and start from scratch. Their team took a look at several viable head tube angles and fork offset combinations. They had them test ridden on trails and gleaned data and feedback from these riders to determine where 29″er front end geometry needed to go. The result is G2.

So What Exactly Is It? Well, it is a longer offset, (51mm) and a bit slacker head tube angle than what you might have thought. Really, the numbers do not add up to a lot of the “number crunching” crowd. I even heard that come out of some Fisher testers mouths: That they couldn’t believe this is what felt the best out on the trail. They told me it solved both Problem #1 and #2, and that the bikes were much more like 26″ers than any other 29″ers handling-wise. Well, I’m glad it made the cut, because it certainly does work out on the trail. The bikes just are easier to pilot and are much better at slow speed maneuvering than previous 29″ers were.

Is This Really All That? For a lot of 29″er freaks and for the new folks looking into 29″ers for the first time, G2 will be a welcomed thing. Of course, it isn’t for everybody, and their is no “easy button” when it comes to figuring out what will or will not work for you. I will go out on a limb and say this: G2 geometry will be copied and will be a big influence on 29″ers design for the future. It won’t be on every bike in the future, nor should it be. However; it is a big turning point in the efforts to clear up Problems #1 and #2 with 29″ers.

Advertisements

No Responses to “Gary Fisher HiFi Deluxe 29"er: The Technology of the Ride”

  1. MMcG Says:

    One thing you don’t mention is that this new G2 isn’t only being used on 29ers GT – it applies throughout the Fisher lineup in both 29″ and 26″ wheeled guise. So it is not a 29er specific change right? So is it just a bike thing or is it truly a 29er thing?

    I welcome your thoughts.

  2. BearSquirrel Says:

    I scoff at the gyroscopic argument in regards to turning. Those wheels aren’t moving fast enough to be noticeable when you have two arms to turn the wheel with 10+ inches of leverage on both sides. I think we are seeing the effect of typically longer top tubes (to avoid toe overlap) and a different “feel” that requires more steering input.

    Come on, who really things it’s “hard” to steer a 29er?

  3. dosboy Says:

    the only time ive felt a gyroscopic effect on any wheel is with an endomorph on a large marge rim going quick on hardpacked downhill trails. No standard 29er wheel has ever made me feel anything like it.

  4. Guitar Ted Says:

    MMcG: You are correct that G2 is also a 26″er developement, but when you dig into it, there are very big differences between the 26″er G2 and the 29″er G2. The offsets are different, (46mm/26″er vs. 51mm/29″er), and the head angles are slightly different as well.

    BearSquirrel: Well, you are correct in that there is a “different feel that requires more steering input” and I’m saying it’s partially due to the greater gyroscopic effects of the 29″er wheels.

    Think about these things: 29″ers carry more momentum. 29″ers are more stable on downhills. 29″ers are harder to change the direction of travel. All because of the inherent wheel size difference from 26″ers. (more mass at a greater distance from the axle) These are things that we as 29″er freaks have taken as part of what we like about the ride. (Well, maybe not so much the steering issue)

    However; I won’t be surprised when I hear that someone won’t like G2 geometry because it makes going through rock gardens and root infested terrain to much work. Why? Because G2 eliminates some of that front end stability/resistance to changing direction that some see as a sort of “steering damper effect” of big wheelers. So, as I said, not all will embrace G2, nor should they.

  5. MC Says:

    Heya Mark-

    Thanks for taking the time to give details on G2 in a well-thought-out manner that chimps like me can understand.

    It’s rare that I feel the need to chime in on these things, but something about your article compelled me to write.

    And that something is the word “problem”. You qualified your use of the word a few times over with broad based disclaimers, but that doesn’t really change what you’ve done overall. And what is *that* you ask?

    Simply, you’ve called into question that which some of us ‘early adopters’ have *LOVED* about 29″ers since way back when: the ‘detwitchification’ of the bike!

    Call ’em slow, call ’em sluggish, call ’em barge’s. Call ’em wagon wheelers or anything else you want. They handle differently from 26″ bikes and that bit of perspective is necessary and beneficial. But ‘problem’? That’s a piece of perspective that is rider, bike, trail, and situation based, and calling it a ‘problem’ across the board is not just inaccurate, it’s plain false. The shoe just doesn’t fit.

    You said yourself that what G2 does is to make a big wheeled bike handle more like it has 26″ wheels. Many of us left that format dead and dying on a mountainside for good reason: it sucked. We threw suspension and more suspension at it. Bigger tires, faster tires, and tubeless tires. As you’re well aware, none of the band aids we applied to the smaller wheels could cover up the suppurating wound of their inferiority. I’ve said it before and I’ll say it again: No amount of suspension can keep a 26″ wheel from falling into a 28″ hole.

    Instead of using the word ‘problem’, I think ‘solution’ is far more appropos. The increased trail, increased stability, and increased gyroscopic inertia of the big wheels have all increased the pleasure I derive from riding a bicycle. I fail to see a problem with that.

    I applaud Fisher’s efforts and commitment to evolving and improving the breed, and while I’m sure there are some out there whom will benefit from G2, I ain’t buying.

    Best,

    MC

  6. BunE Says:

    I had a long talk with my Fisher guys here in KC and was able to ride the HF Pro. They liked the G2, thought that it handled great and made for a more direct ride. That being said, we all agreed that it was nice to see a new step in bike design, but the change was less than radical. I tooled around on the HiFi and then hopped on my super cal and was not really swayed either way. (Though the colors were better on the HF). The Fisher guys said that that Race Day design was pretty quick in and of itself and the head tube angle/Reba combo made for great handling.

    I too am pleased that we are seeing innovation and experimentation in the bike industry, 29er or otherwise. Go GF!

    Unfortunately, the KC area is about to get iced, could make for some great conditions at the national cyclocross championships though.

    Cheers

  7. Guitar Ted Says:

    mc: Okay……….solution it is, fair enough. 🙂

    I figured there would be someone chiming in here to give me the raspberries about G2 and “handling like a 26″er”. May I point this out from the comment above as an example?

    “However; I won’t be surprised when I hear that someone won’t like G2 geometry because it makes going through rock gardens and root infested terrain to much work. Why? Because G2 eliminates some of that front end stability/resistance to changing direction that some see as a sort of “steering damper effectâ€? of big wheelers. So, as I said, not all will embrace G2, nor should they.”

    Fair enough short version of what you are trying to say there, albeit without the front suspension comments? I know that 29″ers champions were celebrating these differences from the get go, but as we have seen, a more “26”er-centric” approach has been applied to 29″er developement ever since by small builders and big corporations alike. Good or bad, that’s the standard 29″ers are being judged against- the 26 inch wheeled mountain bike.

    It is the “baseline” of the sport, if you will. I’m not sure that could ever be seen as good or bad, just that it “is”.

    Thanks for your considered comments. I always enjoy your take. 😉

  8. Desert9r Says:

    The one thing that I wonder about G2 and fisher bikes, they are all suspended/ G2 seems to be designed for suspension/suspeneded bikes, What would a rigid G2 bike feel like?

  9. Guitar Ted Says:

    Deasert9r: Like an On One Inbred 29″er. 😉

  10. Dirt McGirt Says:

    GT- Way to school it. I couldn’t have done it better myself!

  11. BunE Says:

    As of Today the Super Cal 29 is off of the GF website.

  12. Bruce Says:

    What?????? I love my Supercaliber!!!!!!!

  13. Davidcopperfield Says:

    @ Guitar Ted I posed a legitimate question on mtbr.com and one could ever answer it.
    It flows like this “what is the best angle at which sus. fork compresses?” Why G2- 71 HTA on hi fies with 51mm. why 69 HTA with 51mm why is there such a diffrence within GII?
    And if 69 HTA why not mate it with 60mm offset forks? Do you think that 69 HTA with 60mm around offset forks + shortened Top tube by the odd amount of mm, would be more efficient or 71 HTA + 51mm is just the best?
    DH 26 ers have 67-68 HTA and do pretty well therefore we could make a 67 HTA + 65-75mm offset fork 29er? We would get this same trail amount as on 71 HTA + 51mm but how would these bikes differe from another supposing that we appropriately shortened top tube to suit hta+offset combo to get this same wheel base.

    Has anyone of you expertise on this one?

  14. Guitar Ted Says:

    Davidcopperfield: I think we might have an excellent case of an example of “diminishing returns” here. Think about this: It is obvious that at a certain steepness of head angle that a suspension fork starts to become less effective. Conversely we can say that at a certain slack angle we will notice the same thing, that is the suspension fork starts to work less effectively. Traditional thought is that a suspension fork works best at a perpendicular angle to bump forces.

    Taking these basic theories into account I think it is fair to say that a certain degree of head angles will produce the best results for a given application in mountain biking. Your example of DH/FR/AM bikes is a bit extreme when taken into consideration that most 29″ers that are using suspension are geared towards XC/Trail riding today. To have a precise steering bike is one thing, but to have a really quick handling DH rig is not necessarily desirable. In fact, it is usually seen as a detriment to that sort of discipline.

    I think G2 is best suited to XC/Trail type riding and therefore the head angles best suited to that sort of riding/suspension fork performance are about where we are today. 70-72 degrees for 29″ers.

  15. Davidcopperfield Says:

    Yes, that is of course correct what you say about DH 26″ – (I put it forth just as an example of slack HTA), however do you think that for instance 68 HTA with with about 75mm (the equivalent of 51mm with 71 HTA) offset is better or worse than 71 + 51mm? Which one is more the most perpendicular angle to bumps&obstacles?

    You clearly remarked that GF staff wiped the slate clean, in fact, they did it with offset and srted with old and reliable HTA 71 which was settled in 26er world long ago.
    Why didn’t they start from the scratch entirely?
    I mean one can argue that the most perpendicular fork level is at 70,5 with about 54mm offset with further shorter TT from original G 2. Or 70 with 57,5mm.

    Or the slacker-more offset (under 71 + over 51mm) package will deteriorate uphill climbing?

    How much trail would you/one see on DH 29ers at least and at most and how slack could we venture + how much offset. Of course for DH 29ers we need about 90-100mm offset- just a guess, and whatever the trail number how can we achieve it? how slack with how much offset?
    These are fundamental questions which question the geometry.

  16. Davidcopperfield Says:

    Of course for DH 29ers we need about 90-100mm offset- just a guess. Just a Typo I meant a TRAIL. sorry.

  17. Jared Says:

    Just for the record: Per the GF 2008 catalog the HA on the G2 full-squish geom is 71 (69.9 sagged) and 69.9 on hardtails (w/ the exception of the small and medium sizes which are 69.3)

  18. jeremy Uk Says:

    I’m in England and thinking of getting a 16″ inbred 29er. It’s set up at 71degree head angle and a 470mm fork with a 58mm BB drop
    If I were to wait maybe 8 months then I could put on a G2 fork at 100mm and about 510 length.
    Running maybe 20mm of sag would still leave me a slacker head angle and I’d just need an inline seatpost to compensate. The BB would be maybe 8mm higher so I’d end up with a BB 3mm higher than a G2 ali Fisher hardtail and a head angle pretty close to the Fishers, maybe a hair steeper.
    There must be quite a few makes around with similar geometry that could be altered.

  19. Desert9r Says:

    I might just get a feel for that geometry, the owner of my LBS is selling an Inbred 456 frame, a little alter but I have heard its a SWeet ride!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: