Rake and trail

[lightspeed]

Question for the mechanics and builders.... In newer bikes, is it possible to adjust the rake without rebuilding the front end?

[rybo]

Question for the mechanics and builders.... In newer bikes, is it possible to adjust the rake without rebuilding the front end?

Yes and no,

Some ducati's have adjustable head tube angles that will allow you to adjust rake (and by default, trail). Other than that you would need to purchase triple clamps with adjustable offsets to change the rake and trail on the front end of the bike.

Rake is also affected by changing front and rear ride height. Again, some high end bikes offer rear shocks with adjustable lengths, but most do not. You can adjust the front ride height by moving the forks up and down in the triple clamps. I suggest only moving them a few MM at a time as the effects on handling can be drastic.

Hope that helps

s

[lightspeed]

Thanks....this makes sense. I know on my last road bike...it was possible to adjust the rake without changing the geometry of the frame. So increasing the rear height would increase or decrease the rake? Decrease??

[asp_125]

Decrease, you're making the forks more vertical.

[Scer]

Yep, what scott said and also just changing the size of the tire will lower the rake as well. That's why you might get the nice tank slappers effect going on with high speeds when you make that jump from the small tires to bigger ones. Also take in the effect that as you travel faster the tire does grow due to the heat and centrifugal forces on it. So if you are on a high speed track/course try to adjust for that as well. Not all tires grow the same either.

adjust on adjustas

[lightspeed]

Interesting... When you say changing the size of the tire...you mean, rubber front, rear or rim diameter. Can you go into detail about that?

[Scer]

Mostly I am talking about the rear tire. because most of the front tires are the same sizes when it comes to DOT's. (The tires with grooves in it, non-slicks)
The aspect ratio (second number in tire size) tells you the sidewall height. So a 190/60/17 has a side wall of 190*60% or 190*.6=114 which means the sidewall height on that tires is 114 mm.
Then, on a 190/55/17 tires the sidewall is 190*55% or 190*.55=104.5mm
Thus the difference in sidewall height between the two tires is 114-104.5=9.5mm Therefore, to compensate for that difference in height you will need to adjust your suspension accordingly.

learn on learnas

[lightspeed]

Mostly I am talking about the rear tire. because most of the front tires are the same sizes when it comes to DOT's. (The tires with grooves in it, non-slicks)
The aspect ratio (second number in tire size) tells you the sidewall height. So a 190/60/17 has a side wall of 190*60% or 190*.6=114 which means the sidewall height on that tires is 114 mm.
Then, on a 190/55/17 tires the sidewall is 190*55% or 190*.55=104.5mm
Thus the difference in sidewall height between the two tires is 114-104.5=9.5mm Therefore, to compensate for that difference in height you will need to adjust your suspension accordingly.

learn on learnas

Excellent info! Thanks, I never knew this..