To fully explain rake/trail geometry and the reasoning behind it would be a full book chapter, so here's the short version...
Each manufacturer decides what suspension geometry to have on a given bike. Factors taken into consideration are spring rates, shock damping, center of gravity, and overall bike weight among others. They're looking for the 'best balance' in handling, ease of riding, and safety; there's always tradeoffs involved. The 'type' of bike it is makes a difference too. But generally speaking, you'll see trail numbers of between 4" and 6" as the norm, with numbers under 5" usually being confined to sportbikes with their lighter weight and better suspensions. Larger, heavier bikes will run numbers in the 5 to 6 range. There are exceptions to this (you'll see pro-built choppers with lower trail numbers, but these have frames that are stretched in the downtubes/backbone), but these are general rules.
The effects of trail are these; less trail will give lighter steering effort, faster steering, but the bike will be prone to 'head shake' (violent oscillation of the bars back-and-forth) if 'upset', also known as a 'tank slapper'. The really bad part of this is the bike probably won't give any warning before it happens. The bike will also be less stable 'at speed' (needing more attention to keep it going straight). Many sportbikes with low trail numbers are fitted with steering dampers to help with this.
Too much trail has the opposite effect; heavy, slow steering, and the bike wants to go straight, resisting fast manuevering. No chance of a tank slapper.
As an anology, the effects are somewhat similar to oversteering/understeering in a car; the best 'balance' is neutral steering, but if you miss that, understeering (too much trail) is more easily controlled.
What makes this particularly bad on a XS is with the stock suspension geometry, they're prone to head shake already if you push the bike. Fork braces can help with this, but with your non-stock combo you may not be able to find anything to fit. You've got two strikes against you; you've reduced the trail with the fork/tree combo, plus by hardtailing the bike you've put added stress on the front suspension. Not at all good. The easy fix? Swap the 'standard' triple trees you have for 'Special' trees, you'll at least remove one strike. I'll also point out that those smaller-than-stock front brakes are another bad thing; the OEM brakes are only 'adequate' for a bike of this power/speed capabilities, you may find you have way more 'go' than 'whoa' with those smaller brakes.
I'm not trying to bust your chops, but if you end up as a greasy smear it won't be because you weren't warned....
For a rake/trail calculator which might help explain it better, look here: http://www.rbracing-rsr.com/rakeandtrail.html
As to 'what' bike you have, check your frame number against this: http://www.xs11.com/faqs/153-serial-...ry-colors.html. The frame controls pretty much what you can swap around.
Each manufacturer decides what suspension geometry to have on a given bike. Factors taken into consideration are spring rates, shock damping, center of gravity, and overall bike weight among others. They're looking for the 'best balance' in handling, ease of riding, and safety; there's always tradeoffs involved. The 'type' of bike it is makes a difference too. But generally speaking, you'll see trail numbers of between 4" and 6" as the norm, with numbers under 5" usually being confined to sportbikes with their lighter weight and better suspensions. Larger, heavier bikes will run numbers in the 5 to 6 range. There are exceptions to this (you'll see pro-built choppers with lower trail numbers, but these have frames that are stretched in the downtubes/backbone), but these are general rules.
The effects of trail are these; less trail will give lighter steering effort, faster steering, but the bike will be prone to 'head shake' (violent oscillation of the bars back-and-forth) if 'upset', also known as a 'tank slapper'. The really bad part of this is the bike probably won't give any warning before it happens. The bike will also be less stable 'at speed' (needing more attention to keep it going straight). Many sportbikes with low trail numbers are fitted with steering dampers to help with this.
Too much trail has the opposite effect; heavy, slow steering, and the bike wants to go straight, resisting fast manuevering. No chance of a tank slapper.
As an anology, the effects are somewhat similar to oversteering/understeering in a car; the best 'balance' is neutral steering, but if you miss that, understeering (too much trail) is more easily controlled.
What makes this particularly bad on a XS is with the stock suspension geometry, they're prone to head shake already if you push the bike. Fork braces can help with this, but with your non-stock combo you may not be able to find anything to fit. You've got two strikes against you; you've reduced the trail with the fork/tree combo, plus by hardtailing the bike you've put added stress on the front suspension. Not at all good. The easy fix? Swap the 'standard' triple trees you have for 'Special' trees, you'll at least remove one strike. I'll also point out that those smaller-than-stock front brakes are another bad thing; the OEM brakes are only 'adequate' for a bike of this power/speed capabilities, you may find you have way more 'go' than 'whoa' with those smaller brakes.
I'm not trying to bust your chops, but if you end up as a greasy smear it won't be because you weren't warned....
For a rake/trail calculator which might help explain it better, look here: http://www.rbracing-rsr.com/rakeandtrail.html
As to 'what' bike you have, check your frame number against this: http://www.xs11.com/faqs/153-serial-...ry-colors.html. The frame controls pretty much what you can swap around.
It was a one owner, and perhaps he did things without thinking. That is exactly opposite of what I intend to do. If its wrong or unsafe, I'm not going to keep it that way. I don't want to kill myself or anyone else if something is not correct.
As for the tank slapper syndrome, nothing yet, but I'm very familiar with death wobble on linked suspensions, so there is no way I'm gonna mess with it on a bike.
The brakes seem to stop ok, but then again, I don't drive the bike fast either. It was really just to putz around. But, I'll see about getting bigger brakes (safety is always a good excuse to modify)
I will build a fork brace for it if I can't find anything. Welding/building isn't a problem, just needed to know what to do!
Any suggestions on where/what to get bigger brakes from? What would I need for the swap?
) , how do I decipher if it is truly a special or a standard?
The big problem IMHO is with low trail is the bike is more easily 'upset' and under the 'wrong' circumstances can develop a nasty tank-slapper without much warning, particularly for the unaware. Large bumps in corners, transitions across RR tracks, things that may give you pause even when cornering with a 'good' trail number are the usual culprits. The over-length tubes installed on yours helped bring back some trail by effectively increasing your neck rake. But I knew a couple of guys who had 'underwear changing' experiences with low trail, and at least one guy who got hurt. An experienced rider will have a better shot at maintaining control, but somebody with less skill may not be so lucky.
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