Rake adjustment

[Waffa_imp]

Hey all, I've been looking around for after market triple trees for our cb. I want to decrease the rake(27 degrees) by a couple of degrees. I haven't had any luck with my search and decided to ask the forum to see if anyone has had any luck or a good place to search.

Thanks, Waff

[FUZZY_imp]

Why? Wouldn't think you would like handling afterwards.

[Waffa_imp]

Why? Wouldn't think you would like handling afterwards.

I graduated college with a concentration in 4 wheel and 2 wheel vehicle dynamics. I created a computer model where I insert the geometry of the bike to analyze and predict the handling characteristics.

I would be most concerned about finding enough information about the fork seals to see if they can handle the loads when I change the offset. It would most likely end up being trial and error on the fork seals.

[Deanohh_imp]

How far can you reduce the trail before it oscillates at high speed like a bent shopping cart wheel.

[ChipBeck_imp]

Why? Wouldn't think you would like handling afterwards.

I graduated college with a concentration in 4 wheel and 2 wheel vehicle dynamics. I created a computer model where I insert the geometry of the bike to analyze and predict the handling characteristics.

I would be most concerned about finding enough information about the fork seals to see if they can handle the loads when I change the offset. It would most likely end up being trial and error on the fork seals.

Waffa,

Wouldn't decreasing rake also decrease the loads on the fork seals? And although it would lower ground clearance couldn't you test out slightly less rake by sliding the fork tubes up in the triple clamps?

Chip

[Waffa_imp]

Why? Wouldn't think you would like handling afterwards.

I graduated college with a concentration in 4 wheel and 2 wheel vehicle dynamics. I created a computer model where I insert the geometry of the bike to analyze and predict the handling characteristics.

I would be most concerned about finding enough information about the fork seals to see if they can handle the loads when I change the offset. It would most likely end up being trial and error on the fork seals.

Waffa,

Wouldn't decreasing rake also decrease the loads on the fork seals? And although it would lower ground clearance couldn't you test out slightly less rake by sliding the fork tubes up in the triple clamps?

Chip

Waffa,

Wouldn't decreasing rake also decrease the loads on the fork seals? And although it would lower ground clearance you could you not test out slightly less rake by sliding the fork tubes up in the triple clamps?

Chip
That is correct, but decreasing the rake will increase the trail which I would have to fix by changing the offset. And the moment generated from a bump impact on that offset is what I'm worried about.

Since the triple clamps are parallel with the head tube angle, sliding the forks up wont change the trail (one of the main handling properties). The main goal I'm going for is the look of steeper forks. While making a few other changes to maintain/tailor the current handling properties.

[Deanohh_imp]

You're saying decreasing rake angle (steering stem angle) increases trail. ......sure about that?

But perhaps you could show a scale diagram of what you're trying to accomplish. I've never seen a set of triple clamps where the yokes are set to angle the fork tubes more vertical than the stem, plus have a bigger offset to maintain the same trail. Is that what you're asking?

I don't get the purpose but I hope you find what you're looking for.

[FUZZY_imp]

I dunno?

[Ack-CB11_imp]

Triples are out there somewhere, this bike has a set. Those forks are awesome with real brakes up front.

http://www.samurider.com/?p=13643/#itemImage

[oldgoat01_imp]

You're saying decreasing rake angle (steering stem angle) increases trail. ......sure about that?

But perhaps you could show a scale diagram of what you're trying to accomplish. I've never seen a set of triple clamps where the yokes are set to angle the fork tubes more vertical than the stem, plus have a bigger offset to maintain the same trail. Is that what you're asking?

I don't get the purpose but I hope you find what you're looking for.

OK, I admit to knowing next to nothing about this topic; however, I am in the same place. Doesn't a reduction in the rake have to reduce the trail all other things being equal? Or is that the original question, i.e., find some offset triples that maintain the trail while decreasing the rake?