Murray Washburn started out racing BMX when he was five. He went to college in Colorado, where they issue you a mountain bike when you hit the state line, at the time when mountain biking was in its infancy. He worked as a shop guy in Colorado for many years, in sales and service, working with racers and wrenching for racers. In 1997 he started working for Cannondale and has held a number of roles since then, including sales representative, race mechanic and product manager technical representative. Today he is the Global Director of Product Marketing, which is the link between Cannondale’s Engineering dept and the outside world. He describes himself as a "supremely unqualified engineer, but someone who loves knowing how stuff works." What is a fork-offset?
When you're talking about geometry and handling, there are three things that are interrelated. Why should people care about this?
First there’s head-angle, which is the angle of the head tube. If you a draw line right through the head
tube and steerer tube and take that all the way down to the ground, that's your head angle. Then there’s
fork rake, which is the amount the front axle sits off that centre line.For mountain bikes, it can also be
referred to as fork offset. It's been hovering around 45-50mm of offset.you can gain fork rake either through
angling the stanchion tubes at the crown, or offsetting the dropouts, but the net result is the same Rake
and offset together create a measurement which is called trail. This is a measurement where you take
that head angle line extended to the ground and then you find where the axle is and you draw a line
vertically down to the line. The difference between where the first line and the second line intersect the
ground is called trail.
There is no easy way to think about rake and trail, because if you go too far one way, or too far
the other, the affect flip-flops. From a mountain biking standpoint, the easiest way to think about
is that head-angle controls and affects high-speed and low-speed stability. Meaning, the more you
rake it out, the more floppy to one side the bike gets at low-speeds, the more of a handful it is on the
climbs. But,when you're travelling at high speeds, it not only aligns your suspension with the oncoming
impacts, but gives it a really planted, solid feel that makes it hard to maneuver it off line. When people talk
about slack head-angles, they generally refer to it in relation to 45 to 50mm fork offsets. If you think
about what the demands are for all-mountain riding, you want a bike that's really stable at speed,
but you also want it to be maneuverable when it gets slow. You look at enduro riding, where they've
got massive high-speed sections, but they've also got tight hairpin sections, quick little uphills,
you've got all these different things. The idea would be that you've got a bike that has really nimble
handling at low speeds, but is rock-solid at high speeds. We've been playing around with different
head-angles and different fork offsets to achieve that.
How do you apply this to your bikes than? Doesn't a slack head-angle just mean poor low-speed handling?
The most obvious example is the Trigger 29. We took what is normally 45 to 50mm of offset, and we push it out to 60mm of offset. If you look at the SuperMax axle, you can see that there is a big offset of the dropout there. What that does is allows us to kick the head angle back to a relatively slack, 69 degrees, which if you kept that with a 45-50mmmm rake on a 29er, you would have the most sluggish handling bike in the world. It would be great at high speed, but the second it slowed down it would just be a pig. By kicking the head-angle out and kicking the fork rake out, it does the counter-intuitive thing of reducing the trail. If this is so vital, why isn't this something we hear more about?
Most bike manufacturers design around industry standards and creating change within that world is slow and difficult. Suspension manufacturers build forks that are consistent to each other based upon OEM stuff and, like everything in mountain bikes, people accept things as standards and rarely think about them in a different way. Cannondale is a frame and suspension company first and foremost and we have the unique ability to change angles where we see performance improvements.
If the head-angle was the only factor, the answer would be yes. Thankfully though, this stereotype
is just that. Handling is one of the things that, up until now, has been holding back longer travel 29’ers.
At low speed, there is a natural tendency for the big wheels to be sluggish. Frame designers have been
using steeper head angles to help, but it was at the expense of high-speed stability. That is not a lot
of fun for a bike that naturally wants to go fast. By adjusting both head angle and trail, you can get a
bike that handles just as incredibly well at high speed as it does at low speed.
Why don't you just eliminate the trail then to make slack bikes that handle incredibly quickly?
Ben Cruz aboard a Cannondale Jekyll with a prototype SuperMax.
You need trail to offer some stability to the bike. Without it, the front wheel would behave like the wheels on a shopping cart. It is the balance of these subtle ingredients that separates great handling bikes from the rest. Cannondale
The tech articles on Ibis' site are a good example, great explanation without even mentioning their own products - to me this is actually more of a reason to go for their products.
FYI I still dig Cannondale, especially the Lefty's. I I'd win the lottery I'd put one in my Honzo..
If you do keyed single sliders, look at how they do it on nose landing gear of an airplane. A 1955 Cessna is more sophisticated.
No stiction, perfect trailing, might be able to get away without a steering tube.
So the past 15 years hasn't proven that it's not sketchy?
Next time I build a bike I will have to work the most complicated fitting table ever if you guys keep pushing new shit like that on us!
TOO f*ckING BAD they put it on useless SUNTOUR XCM, now trying to find replacement is nightmare, closest I found in same travel is RS Argyle but that means at least new Axle too, right (9mm->20mm). Without proper sub. what will I end up with steep head angle and high speed sketchiness ?
Also 3/4 of producers doesn't even publish their Axle-to-crown, or Offset measurements. And I highly doubt average bike shop around here knows any of this...
I love the idea very very much, honestly but if bike companies want to fiddle with thing so much they should let enough info for customers or at least their retailers.
Thanks Pinkbike for putting this up. More TO THE POINT, DIY, HOW TO (choose/repair) stuff please
inform you of information that may not have been necessarily known or understood by the general masses, explain it to you in relation to their new product which just so happens do defy the "industry standards" and "OEM" shackles of most other major companies and hey you're now thinking "does my bike do that? maybe i should consider this new canondale if i want the ultimate climb and descent machine?"
It's an Ad.
Even high-end 26" XC racing bikes were using slightly different geometries between different designers, before 29" armada came three years ago.
Spec is known for dialed bikes and even them released geometrical nightmare that P.AM was, at the time when they released the SX Trail wonder that finaly debeiged AM bikes.
Everything is about compromises and priorities: and some are f*cked like chain stay length on 99% of bikes being a result of keeping production price low. It costs double or even tripple to make a short CS and keeping it stiff and light. If you just draw a tube all the way to BB/pivot you can't achieve anything short.
Im tired of people making a big deal out of bicycle design when so many good examples are available for comparison.
Now- shorten the chainstays to stiffen the rear end, shorten the wheelbase, and improve rear wheel traction. You now changed your wheelbase, and center of balance. Your bike won't climb as well. No prob, slacken the HTA to lengthen your wheelbase. Slacker is better right? Wheelbase is now normal, but weight distribution is rearward. Climbing is compromised, as is cornering. Lower the bars to get the weight down on the front end. Better high speed cornering, but your breathing is affected on the climbs, and slow speed cornering is off. The front wheel flops on slow corners and climbs (the trail is off, your body is in an awkward position, mechanics are off, excepting high speed declines, except the low bar shifts your upper body weight forward.
BB drop is very important. More BB drop generally allows a lower Cof G. The lower the C of G, the easier it is to get a bike to move side to side. This is offset by the gyroscopic weight of the wheels which want to keep you in line with the rotational direction. Larger wheels allow for more BB drop, at a certain BB height. The difference we feel with 10mm lower BBB height has more to do with BB drop than Cof G. This is a big part of the "magic" ride of the 650b. The BB drop, changes the relation to the wheel axles, keeps the C of G consistent with a 26er, the weight difference in the wheels is minimal compared to a 29er. Trail is more reasonable as we don't kick the front out quite as much, the rider weight remains more centered. There is more room to control rear wheel path than on a 29er, which would end up with a front biased C of G, as opposed to the 26er rear weight C of G.
BTW, I didn't do the neg prop thing.
What they are know for are the same thing as Cannondale - a lot of unnecessarily proprietary parts.
so its harder to ride 26er compared to 650 b or 29er.
sure its hard to ride hardtail with 150 mm fork too. its fun that matters. and if you nail rough section on hardtail , its priceless.
its not bike but rider. 10% is bike 90% is rider . why buy new frames/bikes when you have not reached even 70% of bike potential? Perhaps because you can reach 65% of new bike potential that would be same as 70% of your old because geometry is more refined?
look at Chris Akkrig for instance. Wonder how would he stack in enduro race. he should try it too..
So shouldn't 24" be even better?
Bzzzzttttt. No soup for you!
iamamodel: 24" will be more popular soon, as there's more and more die-hard riding daddys who will be ready to lash out some $ for more developed gravity-bikes for their kids. As soon as bigger companies will smell that market can recieve expensive small bikes, they will push more for kids to emboss their brand on them as early as possible.
Someone needs to develop a person size versus wheels size versus intended use matrix. I think you are the person for the job.
Forget that frame you are working on, this matrix is what the MTB world really needs!
After a new bike? Just answer a few questions: First question: How tall are you, Second question: What is the size of rocks you have on your trails: give the smallest and the biggest (height above the trail level) - 3rd question: how would you describe your current bike:awesome/gay/not sure - 4th question Were you ever masturbating in your car when stuck in a traffic jam? yes/no 5th: have you ever masturbated only by stimulating your prostate analy. yes/no/thought about it - Thank you the D8 system will now process true facts with use of actual science and give you a nonsense free, logical answer...Processing... You should ride 650Bzzzzzzzzz
I feel that 650B will be the future of "ticking clock driven" mountain bikes for competitive people, and along with 29ers they will be the best choice of beginners. It will be interesting to see what comes out of 650b vs 29" in Enduro. But 26ers will redefine themselves as "the shit" as "bike handling connesseurs" bikes, kind of gokarts of MTB. At least that's the future I'd like to push forward with my (hopefuly) future designs. Not everyone has trails on which you can use 26ers potential to jump around. We'll observe a massive yet not complete die out among die-hard 26" riders, in the same way that dies the spirit of riding among people getting into a big change in life, be it finishing school and getting a job, or getting kids. I imagine them to be a niche product in >500$ segment by 2020.
Ok sorry, got carried away, that discussion gave me more than everything all together here since few years.Thanks!
That is off course true to a great point but let's not forget forks suspension performance. At steeper head angles the fork will not absorb high speed hits as well as a fork at slacker head angle, especially a standard fork that uses standard bushings unlike Lefty. While Lefty might cope better with a slider going into the bushings under side load, it will suffer a bit more from deflection, resulting in a slightly increased stability loss after bing struck by the bump.
So in case of a downhill bike going real fast where forces from bumps are acting on the bike more horisontally than on DJ bike particularly, the slack HA is a win-win. On an XC bike, steep HA and long rake is welcome. With Enduro bikes, sorry but we have few years to find the right compromise.
I thought so not so long ago but closer the World Enduro Series came and more I thought about, then I saw vids from Punta Ala. AM bikes are dialed but Enduro will redefine it, because it will add racing experience to them. BIkes are surely being developed with that angle in mind as we speak but it will take two years or so until that research takes form. Geometry and even wheelsizes will be put to the test in the most professional way it has ever happend to mid-travel bikes. For now no one can say which wheel size will be the best one in 5 years. Now we have the pressure for 650B, but racing will determine if it really is the one to go. ENduro will also be the prooving ground for electronic suspension, and unless it gets banned, this is where we will see that steepest development curve. And who knows what will happen because of electronics - will it increase the travel or decrease it and thus alter the geometry? Will it improve the pedaling efficiency so people will be able to have more travel, or will it decrease is because suspension will deal with bumps better?
27" should make the good old ZERO travel hardtail with 4.5" forks gain some performance ground back, even against electronic blah blah.
Oh, and before anyone goes there I've nothing against 650b...
@taletotell - straight talk is rare indeed. Fabien Barel did more straight talk in the bike tech vid for DirtTV than many pros did in their entire career, probably all together. I cannot thank him and Steve Jones enough.
If there's so few people with such spine and balls like Fabien, the industry will feed people with threir usual BS and they will forget it, and tinker "geeky facts" vs "troll assumptions". I wish more people would talk like Fabien. Bike world would be a better place.
A local magazine here in the Netherlands (up/down Magazine) recently featured a test, doing timed runs on 26, 27.5 and 29er versions of the same bike. All were fastest on either a 650 or 29er but the least experienced rider gained the most on the bigger wheels. Obviously far from scientific but still interesting nevertheless.
But then again, maybe training wheels just teach bad habits...
If you want straight talk, Brian Lopes dishes it.
" Why are you riding a 29"? Because its a new bike and we want it to get as much camera time as possible."
Same video, Fabien is a great rider for sure.
Also note, this is not a slam on 29" bikes, it is more of a proof that racers don't always race what they want. They race on what they're paid to race on.
I'm commenting on the idea that the manufacturers push designs that are inferior to 26ers simply as marketing. If the product was inferior, it would lose consistently. If last year's champ has a hard time breaking into the top 5 after a team change the next year, the new company looks inferior. 29ers have won several lighter duty DH races. That in of itself shows they are not only XC machines. They can work in many arenas, and we will likely see DH 29ers along with the 650bs that are upcoming.
What are you yammering about? FOX makes a 2014 36 Float and TALAS RC2 20QR 26in forks...
I led you to where you can open your eyes...
Come on ! This industry has no standards... In the last 10 years we got 2 new wheel sizes, two new handlebar diameters, a bunch of BB systems, 2 X 10 , 1 X 11, 142 rear axle size, 135mm offset rear (pugsley), giant OD standard, 2 chain guide standards...
Slow and difficult to change ?
Steep forks are dangerous. We have shorter stays to help quicken up the steering.
I think you are a bit confused here and if not you're definitely overstating the effect of trail. A Fox 34 29" fors run 51mm offset, are you saying all the sub 69 degree bikes on the market running this fork are sluggish?
It seems to me that Cannondale is just continuing what Gary Fisher started. They are to be commended for picking up this dropped baton. Also, do not be surprised if in two years time we hear that the right offset for a 27.5in bike is closer to what we are currently being advised is appropriate for 29ers! My crystal ball tells me offsets in future will be in the following ranges: 26in - 46 - 48mm, 27.5 - 51 - 53mm, 29in - 58 - 60mm. Head angles will be slacker by about 1 degree. That's my guess anyway.
Catch 22, I suppose - stick with the standards and nothing changes, or innovate and to hell with standards.
No way Jose!