fork vs. clamp question

I've been reading through the posts but don't see the answer. For the 2002 CRF, if raising the forks a few mm simulates swapping the 24mm offset clamps to 20mm, then why didn't Honda just do that in their production 2003 instead of messing with the linkage? Honda isn't as dumb as I am so something tells me that raising the forks a tad must not actually quite achieve the same results as swapping out the clamps to change the trail or jacking up the rear end to put more weight on the front wheel (which is what is reported to have been done for 2003).

What's the Pro and Cons of the 3 different mentioned confused "fixes"?

TIA,

I'm also interested in any feedback on this subject.

I'm trying to decide if I want to install new 20mm offset clamps or buy '03 linkage? It seems to me that installing the linkage would be cheaper, but Honda also lowered the rear subframe to compensate for the increased height in the rear. Is there any disadvantage to running the '02 subframe with the '03 linkage?

Of course, the cheapest way to go is to do as lucky_macy indicates and just raise your tubes a few mm's. I've raised mine as far as they will go (about 7mm) and I'm wondering if 7mm lowering in the front is equal to 7mm of raising at the swingarm pivot.

Raising the forks (lowering the front of the bike) or raising the rear of the bike gives roughly the same effect. Honda is very presice about the way they do things, I've seen them make a whole new frame for a streetbike just to give it 3% more stiffness! Who is going to be able to tell a 3% stiffer frame!? I'm sure they have their reasons for raising the rear instead of lowering the front. One thing is that it also changes the angle of the swingarm which can change how hard the rear tire bites for traction. The main thing is that you don't confuse what Honda did for '03 with what a lot of people do with less offset clamps... it's the complete opposite. By lowering the front or raising the rear you are getting less trail for quicker handling. By going to less offset clamps you are going with more trail. More trail gives you more stabilitly, the bike isn't as nervous but it also lets the wheel flop side to side very easily once you intentionally steer it off-center.. that's what makes it drop into the corner so fast with less offset clamps. Anyone who has ever watched an old chopper with the front wheel out there and way too much trail will see the same thing, at slow speeds turning the forks the front wheel will just kind of flop over to the side.

Going to '03 geometry or going with less offset clamps will both help it drop into a corner quickly but they feel very different and it all comes down to rider preference. As far as buying '03 linkage or just raising the forks... you'll have to judge for yourself. The best place to start is to raise your forks up (I've settled at 8mm higher than stock) and see how you like it... it only takes a few minutes to do and doesn't cost a dime. If you don't like it you can just put them back to stock, simple as that.

I found a two page article in motocross action magazine, Feb 2002, pgs 54-55. They discuss the crf's 2002 front end problems. They discuss wheelbase, weight bias, front center, head angle, fork offset and trail. But they don't specifically discuss raising and lowering the forks. But they do discuss shifing they weight slightly fore or aft of the stock location. In short, because of the overall geometry (caused in part they think in a different article by the engine being placed too far back), the say the front end castors at speed like a shopping cart and Dutch Rolls (wallows) in tight turns. The front wheel turns in and then lifts up, according to the article.

Interestingly, in the article they discuss that lengthening the rear shock would steepen the head angle, put more weight on the front wheel and decrease front center but negatively decrease trail and they were skeptical it would work. I believe that's kind of what Honda accomplished by their 2003 linkage mod.

If you read the article, they claim their trail solution (20mm clamp swapout) was clearly the best solution. They also tested a 22 mm offset clamp. I think when I read it the first time I blew it off as just a way to give one of their advertisers some business.

Is raising or lowering the forks really changing the trail or merely shifting the weight more for or aft? After reading the article I think all it's doing is changing the weight bias by changing the wheelbase. In an earlier article they said to lengthen the rear wheel distance and power through turns with your weight shifted backwards.

What do you guys think about that?

Also, in 2003, Honda appears to be merely shifting slightly more weight onto the front tire without changing the trail. From the article, changing the trail seems to be a genuinely different and superior geometry solution.

To those who have read the article, what are your thoughts?

What Honda did on the '03's, raising the rear end with a new linkage, changed the rake and trail and puts more weight on the front end. Any time you raise or lower one end of the bike without changing the height of the other end you will affect rake and trail.

The biggest problem with the '02 was not that it turned in slow, but that in sweeping turns the front did not bite hard and wanted to drift farther out in the turn the more you got on the gas. I ran less rear sag to help some, but it didn't help enough, and I tried lowering the forks but it caused some headshake. I finally tried the 20mm offset clamps and it was much better...no headshake and you could point the front end wherever you wanted in sweeping turns, and getting on the gas more drifted the rear out instead of pushing the front end out letting you even tighten up your line with a powerslide. It did make the bike turn in very fast, which took a little getting used to, and the front end was heavier when going through rolling whoop sections(took more strength to hold it up), but it was a much more raceable setup that let you put the bike where you wanted it with much less effort.

However, I like the stock '03 setup even better. The '03 setup gives it a very neutral feeling, meaning it will go wherever you point it, and the front end feels lighter than with the 20mm clamps. It also does not have the headshake my '02 did when the forks were lowered. In short, it is easier to ride and less tiring to ride than a stock '02 with any setup or an '02 with 20mm clamps.

If it was me setting up an '02 again I'd choose the '03 linkage over the 20mm clamps, and I wouldn't worry about the slightly taller subframe on the '02 unless I was short enough that seat height was a problem. But if I couldn't use the '03 linkage, I'd run the 20mm clamps over stock any day.

Thanks for the post, mxaddict. It's the specific analysis and advice this newbie was looking for.

Next question though is, just what linkage parts need to be reordered? Anyone have specific part numbers or names? Heck, what's the $ damage come to? :-) Anyone tried it yet and found any snags?

TIA again!

Being the Low budget, due with what I have, fix it myself type of guy I am (CHEAP SKATE)! I read alot about what people were doing, studied steering geometry theory and came up with a plan of action to utilize the adjustability of the bike in stock form. Here is what I did.

1) raised the forks in the clamps, scribe line doubled above

2) set the sag to minimum about 90mm

3) set the rear wheel as far back as possible with new chain

4) got rid of that crappy dunlop 490 front tire! ok for xr's

5) played with the clickers front and rear

I am very happy with mine!

If I had the money to burn, I'd just special order from BBR

Randy

see the 'Clamps or linkage' thread for prices...

Excellent post mxaddict, your testing results are right on the money.

So by pulling the rear wheel backward, you are raising the rear end up, therefore putting more weight on the front? Is that correct? Lengthening the wheelbase will make it turn a little slower, but put more bite on the front wheel?

I believe that's mostly right except for the part about raising the rear end up. That would only occur if the swing arm sloped dramatically down from front to rear. Moving the wheel back then would cause the rear end to stand taller but in this case it's a very gentle slope when you are actually sitting on the bike so the effect is minimal. I'm not near my bike right now but that's what I recall the swing arm angle does under the weight of a decked out rider under normal preload.

If you want to jack the rear end up, increased spring loading would do more with less for you. But that also has negative consequences if taken too far.

All other things remaining the same, lengthening the wheelbase in general adds stability to the bike but increases it's turning radius. It does not raise the rear end up appreciably by itself when you add wheelbase by moving the REAR wheel out but it shifts the center of mass slightly forward which means the front wheel is carrying more of the static load. Everything is a compromise. In this case, if you'd rather have more weight of the bike carried on the front tire so the tire will "dig into the ground" easier and hold a truer course at the expense of a heavier feeling front end (not as good for whoops and jumps) then this change will do that.

Lowering the front forks a tad also moves the center of mass slightly forward and puts more static weight on the front tire without the negative effects of moving the rear wheel back (as in moving the rear wheel back increases the turning radius and makes it harder for the rear wheel to break free and whip around I believe).

2mm-4mm Thats all the adjustment in one area we are talking about with a pair of $300 to $500 triple clamps!

fork tube hieght aprox. 30mm adj.(FREE)

sag adj. 10mm within recommended spec. 90-100mm (FREE)

rear wheel adj. aprox. 30mm or more (FREE) may cost some chain!

comp./rebound adjustments (FREE) just time experimenting

Moving the rear wheel back will raise the ride hieght, especially when braking for corners.

Also a higher profile rear tire, and a lower profile front tire can change the weight bias front to rear, something to consider when buying new tires! I would guess you could get 100mm difference or more from tire profile selection :)

Randy :D

If a 4mm change doesn't sound like it would make much difference, then consider what a 4mm increase in your bore or stroke would do for your bike! :)

It's all about where you make the change!

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