looking to increase trail on my 748, seeking a set of yokes. Variously reading on the interweb ( a dangerous thing ) I'm given to understand that 848's are a drop in, then alternately told the steerer stem is too long, and to go for a set for 1098 series. Asking Forsaken Motorsports, ( who do a nice looking set with offset adapters ) they say that 1098 ones wont fit a 748... Anybody experience in solving this conundrum ? ( or maybe have a good set to move on ?? ) cheers joeg
Firstly why? Secondly, trail is a function of the steering column in which the head bearings sit, which is welded to your frame, changing the triple clamp above & below that won’t alter the trail. To alter the trail you’d have to either change the angle of the steering column or lengthen or shorten the forks. Depending which model 748 you have, you may have the ability to adjust the angle of the head bearings within the frame’s steering column which in turn will have an effect upon the rake and trail, but we’re talking about just 2-3 degrees here. In the owner’s manual it’s referred to as road or race setting, the latter being slightly less rake (and thus slightly less trail) resulting in a faster turn in for the track, but possibly too flighty for the road. If it were possible to increase the trail from the standard road setting you’d find the bike a lot slower to turn into corners.
thanks for the response. On track with a swing arm angle in order of 10 degrees ( just waiting for my new geometry tools to be finished so i can be incredibly precise ), there is insufficient trail, leading to little to no feel in front end. indeed ive been lucky to catch the front a couple of times. As ive read it, if you subtend the steering axis to the ground, then trail is a function of the plumb line from the c/l of axle, to the ground, so in reducing the yoke offset, you increase the trail.
Ok, I see where you’re coming from now. I’ve just had a quick look but can’t find it but @andyb iirc did a couple of threads on steering geometry changes on his track bikes, or maybe they were posts in amongst another thread . Just search across his posts/threads.
What was the original problem that you were trying to solve? In the list of bikes that don't handle well out of the box I would be surprised to see the 748 present, especially a road bike. What is the origin problem?
lack of feel in front end. Lost it twice on track and lucky to recover it. I've measured the trail in 'relative' geometry, and its 106, so as soon as sag/ rider it may struggle to get above 90mm. Im having a geometry kit ive designed made up, should be with me shortly.
I know it's probably annoying to ask but you've eliminated tyre choice, tyre pressure, tyre wear, suspension set up (inc. valving, spring weight and oil weight / level)? It's surprising to hear of a 748 front end feeling numb and changing geometry is quite extreme. I know it's another likely annoying question, but do we talk about a 748 with adjustable rake or without that?
