We removed the front and rear OE wheels and tires to install a set of 27" ITP 589MS and check for clearance. They fit. While at this stage I decided to pull the shocks off to cycle the suspension and measure bump steer and scrub. Amazingly enough, I found more bump steer (front) than I thought and less scrub (rear).
(Note: Bump steer is the amount the front tires turn in or out as they travel up or down. This is caused by the difference in location points between the arms and the tie rods. Their arc is different so they either pull the steering in or push it out as the arms travel up and down. Scrub is the amount that the rear wheels move in and out as they travel through their arc of movement.)
What I did find is an amazing amount of positive camber on the front.
(Note: Camber is the amount a wheel tilts in at the top (negative camber) or out at the top (positive camber.)
This is going to cause the front tires to roll over even more than normal in a hard turn - especially a set of lightweight OE tires. No wonder it feels a bit squirrely out on the trail.
We ordered a set of ITP radial ATRs. Radial tires squirm less and therefore keep more tread on the ground. The wider front contact will also help. We'll find out!
We also ordered a set of shocks with 2 inches more droop (sag) to get the Brute Force to sit lower. This will also get the arms to lay flatter and exhibit less scrub and bump steer. They should also make the ATRs work even better.
Brute Force and ground clearance:
What is the infatuation of so many ATV owners needing excessive ground clearance? Indeed, ground clearance is good. If there were no laws of physics I'd want 3 feet of it. But the trade-off of even a couple of inches and its effect on the roll center and therefore the adverse handling of the ATV is not worth it. Give me a lower ATV with strong skid plates for the rocks and a smooth underside and good tires for the snow.
I need to remind everyone how we test and how we film. Filming is boring - really boring! Filming requires that you ride this way. Then this way again. And again. Maybe one more time. Now ride that way. Now that way again. No, let's try it this way. How about this way with that......well let me try another approach - with this description.
Two often asked questions are, "Why don't you film a bunch of us riders going riding at this event?", and, "Can I tag along when you film your tests?"
The very first mass-rider event we filmed was the Lady's Day Ride at the Richfield Jamboree in 1999. While everyone was excited to be a part of a "TV show", it didn't take but a couple of stops and turning the entire group around to get that shot from a "better angle", or with the riders "better grouped" for most of the riders to lose the enjoyment part of the ride. They also realized that this was taking way longer than anyone (else) imagined.
So we try not to film any big, fun rides because we've discovered that too often filming the fun ruins the fun!
Every time that we have gathered a variety of riders together to get a more diverse range of opinions and film the test at the same time, we run into very similar problems - it's hard to do two things at the same time. Keeping riders focused on the machines and the specific differences, and to try to film the groups in a vast array of circumstances just gets too overwhelming.
So we try not to film any group test rides because we've discovered that the best way to confuse the whole test is to try to film the whole test process!
The bottom line is that we typically do our ATV tests like this: First we take the still photographs of the ATV. Then we try to run out somewhere close to the ranch and get some general footage of me or of me and another rider in just some various and somewhat typical riding conditions. With the filming done, I am then free to get one or two other riders together to go for a test ride. I very much prefer small groups of just two or three riders as not only does everything go quicker, but you don't cause too much disturbance out on the trails. Plus, when we test, we either try to focus only on the ATV we're testing or at least on it with some very comparable machines along as benchmarks.
This might be a good time to discuss the wonderful "benchmarking" that we always have at our disposal - and something that I just can't emphasize enough. Our shop is filled with samples of almost all of the ATVs. So when we go to test the Sportsman 500 for example, we have at our disposal any number of ATVs to choose from to go along on that test ride. We can choose another IRS ATV, or an ATV that we feel most competes with the Sportsman, or just something we know we'd rather ride.
Now I've seen plenty of folks ride one particular ATV all day long and get quite comfortable with the small idiosyncrasies of that machine. But when you can jump back and forth every 10 miles or so from one, two, or three different ATVs, you tend to find rather quickly what is better and what is not. This gets multiplied further when the riders decide what "other " ATVs to take along. Sometimes there are ATVs that just never get chosen. Others get chosen all the time!
Every time a viewer gets angry because I say something bad about his machine, I have to remind myself that his thoughts about what he has would be different if he hadn't already bought that particular ATV with hard-earned money. If he could come by the shop and spend a couple of days riding each of the ATVs in that class and comparing them, he'd understand more of what I mean. And no, hopping on a buddy's ATV for a quick spin down the trail hardly counts!
So, while it hurts that some viewers think I'm too opinionated, it is the wonderful diversity of ATVs that are constantly at my disposal that help me to always see the cream at the top! And it is that ability to ride all these ATVs that gives me the ability to become so opinionated!
Because I look at all of you as my friends, it is my desire to try to use my knowledge and wherewithal to help direct you to the ATV that is best for you. While I never enjoy an existing ATV owner berating me for finding faults with his ATV, that pain is far overshadowed by owners of new ATVs telling me just how thankful they are to have found the right ATV because of watching the show!
While it is never my intention to hurt any existing ATV owner's feelings, it is my intention to help the new ATV buyer make the right choice the first time!
The good part of filming:
Okay, there are good parts to filming - like touring the Yoshimura R&D complex for ATVSE. Wow! And although they did cover things that I wasn't supposed to see, there was just enough "beating around the bush" talk to get a feel for what's coming - needless to say Suzuki's race team is only going to get faster.
ATRs vs stock and Prairie vs Brute Force:
65 miles of testing — mostly on ATV trails. The tanks didn't go dry, but it was close. By the way, who decided that ATVs shouldn't have a reserve anymore? Both the Prairie and the Brute Force now have the fuel light blink when there's about a gallon of fuel left. Personally I think its a dumb idea. Give me back a reserve switch!
We took one of the ITP guys out so he could see first-hand what kind of difference the ATRs make on the Prairie. That meant we rode a stock Prairie and one with ATRs. Plus, we took out a stock Brute Force so that he could see the difference between it and the Prairie.
It's amazing how much faster the Brute Force is than the Prairie - sure feels like more than just 50cc! And after riding the "knock-kneed" Brute Force back-to-back with the two Prairies, I can't wait to change the tires on the BF 750 — it's gonna be remarkable!
Let me just go over once again the difference that radials make on an ATV: A radial keeps its tread in better contact with the ground. A bias ply tire tends to flex more. In one way that's good. When you lower the air pressure in a bias tire it bends like an upside down "u" to create a flotation pocket underneath. That gives it a greater compaction under its tread and therefore more flotation over the loose and variable surface. But that is at the cost of a lot of flexing — flexing of the tread across the surface as the tire moves and turns. When you turn, the force bends the sidewall. That in turn also bends the tread. That means that the amount of tread and contact patch you have acting against the ground is always changing.
A radial keeps its tread flatter and in a separate flex from the sidewall. The sidewall flexes and the tread flexes, but not as connected together as a bias ply. So as the forces of a turn flex the sidewall of a radial, the tread stays flatter against the ground than a bias tire would.
These factors are all extremely important in an ATV that uses its tires for forward grip when accelerating, lateral grip when turning, forward grip again when braking, and sidewall flex for added springing in the suspension. You want some flex to add to the suspension cushion, but you want very little flex when cornering (or at least you want the flex to flex some, and take a set that is controllable rather than flexing some, and then maybe some more). If the flex is more constant the ATV will be more stable. That is the advantage of the radial design.
The drawback? Typically a radial is a heavier tire. It's weight that is unsprung, and that is the worst weight you can have. That is a whole other story though, and one that very few ATVers ever pay attention to or else we'd see a lot fewer of those huge mud tires ruining handling and robbing power!
A behind the scenes test day at Glen Helen:
Wow! Another great day to be me! We just spent an entire day at a private test session at the Glen Helen Raceway in Southern California. The Team Suzuki Motocross team had the big track rented for secret testing, and IMS/Roll, Elka, ITP had the back track. And we were a part of it!
Martin Lamaroux and his telemetry guru Stephan flew down from Canada just to show us how they could hook up a computer telemetry system to an ATV to measure the shock movement. This is Formula One stuff and it proved an incredible learning adventure. If there are two things I think the average ATVer has no clue to, it's suspension and tires! And although I am an avid study, there is always so much to learn.
Elka can measure the amount of shock movement, the speed of that movement, and where the movement occurs on the track for each shock on the ATV. Think you're using all your suspension? This will tell you. It'll also tell you how much time you spent in the air, which corner of the ATV landed first, and hardest, how long you lofted the front-end, how far you two-wheeled around the corner, and how hard you hit the whoops. And it'll do it lap after lap after lap. Incredible stuff, and something I'm looking forward to testing on me personally in the sand dunes to fine-tune my ATV's suspension to my riding style.
I love to ride the sand dunes, and although it's not as rough as a race track, it is important to tune your suspension so that you use it all. There is nothing worse than having 10 inches of travel but it being so stiff that 90% of the time you only use 50% of it. That is a waste! With that said, Elka told me that they have designed a dune version of their shock - with softer springs and a bit slower damping. I can't wait to try it and should be getting a set for our Project LTZ400 soon!
That project is getting close. We've got the Doug Roll suspension in an exact duplicate of what's used on Doug Gust's GNC Suzuki with the exception of the shock tuning of course. We've got the Yoshimura titanium/carbon fiber exhaust with the super-quiet pack. And we've got a whole bunch of other cool stuff as well, but I'll talk more on that as we start to put it together. Doug Roll is coming up to the shop to show us all the tricks!
Enough of that for now.
We also tested three new sets of ITP tires while we were at Glen Helen! First up were Holeshot MXR4s which are designed to work every bit as well as the MXRs but last longer! The tread (knobs) are more solid at the bottom yet seem to remain as flexible as the older tire. Our pro riders that were on hand, Doug Eichner and William Yokley, both commented on how quickly a pro rider can wear out a tire - at least to the point that for the performance edge, they will reverse it on the second moto and use an entirely new tire on the third race. The MXR4 proved to be every bit as good as the MXR and indeed lasts longer.
The MXR4 seemed to accelerate better because the extra thickness of the lug at its base kept it from flexing, or bending over under hard acceleration. The same held true under hard cornering and braking. And it is a bonus that the compound change makes it hold up longer.
NOTE: When a tire is turning very fast it will wear the leading edge off at an angle. After reversing the tire to once again use the square edge as the leading edge, the tread begins to look like a pyramid.
For regular trail riders the MXR4 looks like it can provide the same performance as the MXR but probably last twice as long! And as an added benefit what we found is that because the tire wore less, and the wear more constant, that the performance remained the same for a longer period through the life of the tire.
We also tested the new Holeshot HD. This is the newest tire for the extreme conditions found in GNCC racing — deep, wet, muddy ruts, and long sections of hard, tight cornering. This tire looks like a Holeshot, but is taller, the tread is stepped on the sides and much more square. While it wasn't a fair test of the tire on the track at Glen Helen, it did give us a chance to try it out and talk to William Yokley about it. William was adamant about how important the added traction was, especially as the track conditions worsened as the race wore on. He said that it would be easier for the front-runners to get by with a lesser tire than it would for all the rest of the racers. The added traction, especially in the very wet, worn, and rutted sections would prove to be a big difference in the end results. Knowing how he rides, I'll take his word on that.
The other tire we tested (let me try to tip-toe around this a bit) was a prototype radial for sport ATVs. Once again, all I can say is that the advantage of the radial's more stationary tread, especially under hard acceleration, cornering and braking is a huge advantage on a sport machine!
And to quickly get off that subject, the other thing we did was to get a bunch of great riders out on the track to test our next four sport ATVs for ATVSE.
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© 2004 DEMAProductions - DEMeyer & Associates
