Raked Trees or offset bearing cups???

[94glide]

Ok folks....think about this one!!!
If I understand the theory behind rake and trail....and I'm NOT saying I do...
But if I stand my bike straight up...take a straightedge and lay it up against the center of my steering neck(axis point)..down to the ground and mark it...then take a straight edge and level and hold it vertical through the center of my axle bolt, and mark it...then the measurement between both marks would be my trail??? having said that..if you take the same bike...and install a set of ..say 5 degree raked trees...and take the same measurements at the same points....the trail will be reduced....I can follow this so far...because of the raked trees the forks are no longer on line with the steering Head(axis point) pushing them 5 degrees further out thus closing or shortening the trail...and it makes sense....BUT what happens if you take the same bike and install lets say 5 degree bearing cups??? do you take the straightedge and hold it up against the center of the steering neck???? or do you hold it up against center of the stem????...which now becomes your new steering axis??? the reason for this is this....if you take that first measurement through the steering axis...which you did with the first two measurements...versus the steering neck which is no longer your steering axis....then the forks would still be parallel to the steering axis...which in my way of thinking would effectivly increase RAKE without decreasing the trail....

What say you all on this one????
JB

[CWeb]

From my understanding, you would use raked cups to correct any trail issues you would have with raked trees. It's not an 'or' question, its more of an 'if, then'

[kmycek]

I wasn't aware that there were such things as angled bearing cups. I do not profess to be a physicist, either. However I am logical.

Raked trees change the trail dramatically because the forks no longer pivot on the neck's axis. The stem and the forks are no longer parallel.

If I understand these angled bearing races correctly, they would maintain the parallel relationship between the forks and the stem. I believe that these would achieve the same effect has cutting off the neck and re-welding it at the new angle.

Changing the neck angle or inserting these angled races will still change the trail, though probably not as much as the raked trees, depending on the length of the forks. If maintaining the same trail is that important to you, then you might want to consider putting a larger wheel on the back (or a shorter wheel on the front) to counteract the effect.

This is all speculation, but it's my two cents...


Keith

[wayne1967]

I've been looking for more info on the raked cups also. They say that longer tubes are a must when installing these.

[jetblue]

here ya go...

http://www.rbracing-rsr.com/rakeandtrail.html

hope that helps

[Rage]

i just posted nearly the same question in the softail section. I was interested in buying the 3 degree raked cups... so if anyone can give a definate explination it would help us tremendously

[jay 21]

in no order:
-raked cups have the same impact of cutting the frame but limits the amount of rake allowed
-longer tubes are only required to maintain stock ride height. for 3 degree i would leave the tubes and lower the rear fora bitchin low ride
-trees at 3 degree are also considered "safe"
-trees vs cups= trees will shorten trail, cups will lenghten trail. more trail heavier feel at the front less trail sloppy/loose feeling at front
-to be honest i don't know if the 3 deg would give you the visual impact your looking for. i believe the v-rod has a 3 degree offset in its trees
-you could use +6 degree trees and +3 degree cups with about +5" tubes and have your trail within spec. and a fairly dramitis effect.


now that i read the links, you can use jet blues link it'll do your math for you.

[csoday]

Back in the '70s, when you chopped a bike, the only place you saw raked trees mentioned were in the cheap ads in the back of magazines. If you chopped a bike you cut off the neck, shortened the top tube and bent or lengthened the down tubes. Raked trees were and still are a cheap, unsafe and unacceptable way to rake a bike.