Fork angle different to steering head angle

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brent j
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Posts: 21
Joined: Tue Jul 28, 2015 9:42 pm
Bike: RL250
Club: Darwin motorcyle club

Fork angle different to steering head angle

Postby brent j » Sun Feb 02, 2020 6:48 pm

Something I noticed while putting my RL together today, the top and bottom triple clamps appear to have different offsets. The fork legs are on a different angle to the steering head. The rake angle is not affected but having the forks on a flatter angle effectively increases the offset of the axle and so reduces trail. I can only assume that as the suspension compresses the rake angle gets steeper but the offset reduces and slightly increases the trail. Theoretically giving an increase in trail and stability.
Yamaha TY250's (twin shock bikes) are set up the same way with the forks on a different angle to the steering head

David Lahey
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Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Re: Fork angle different to steering head angle

Postby David Lahey » Sat Mar 21, 2020 12:41 pm

There are a couple of trials bikes from the 1970s that have the tubes parallel with the steering stem but most have angular offset.
There has been a move in recent years in Twinshock and P65 circles for people to fit custom-made triple clamps that have no angular offset.
It's an interesting field for experimentation.
Another thing that is being experimented with on some old trials bikes is the total trail. It's another good thing for people who like trying out things to see what it does. I remember in the early 2000s I had a test ride on a TL125 special that had a Honda MR175 or MT125 complete front end. The steering on that thing in flat skaty turns was the best I had ever felt on a twinshock at the time and got me interested in such things. The trail with an MT125/MR175 front end is a fair bit more that the standard TL125. Not long after that I started hearing about people fitting late model Alpina triples on their Sherpa Ts, which increases the trail. When I finally test rode one I was fascinated with how different the whole bike felt to ride.

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