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08 ST stock fork length and offset?

Hello to all contributors to this brilliant thread and thank you for all the great info, I was inspired by this thread a did my conversion a couple of years ago and after two years of riding my 08 ST with 2012 Busa forks I feel the need to increase the fork length a tad more towards stock but have forgotten and lost my notes on the project and since then this thread has grown to over 500 postings and so I either sift through each post or take a quick shot and ask if anyone can remind me of the 08 ST stock fork length and offset? also any suggestions on how to increase fork lengths would be very much appreciated? I am not sure of the screw in top segs with bottom inserts does anyone have any knowledge or experience of these or perhaps increased fork stanchions? or mods to upper clamp?
 

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Discussion Starter #522
Can I ask the reason behind your need to increase? No criticism intended, just like to understand what it's doing (or not)
Incidentally raising fork length will increase the trail even more than the already longer trail caused by the fork offset; so increasing fork length to 'same as stock' is going to take you even further away from oem geometry
But maybe you're looking for more clearance or????
 

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Can I ask the reason behind your need to increase? No criticism intended, just like to understand what it's doing (or not)
Incidentally raising fork length will increase the trail even more than the already longer trail caused by the fork offset; so increasing fork length to 'same as stock' is going to take you even further away from oem geometry
But maybe you're looking for more clearance or????
Hi, No problem, I have been riding the bike with the conversion for almost two years now and have been tweaking and adjusting the set up periodically to get it just right, I am now at a stage where the front is just sweet but to a cost of no preload on the rear, the front forks are dropped thru the top clamp by 5mm and this has given me a rake of 22.5 degrees and the trail is 85mm but I am on the limit of adjustment and nothing left to play with on the rear, I have installed the complete front end of a 2012 Busa but kept the ST wheel, in hindsight there could haqve been better choices but I am there now and have had to incorporate bespoke axle spacers, rotor spacers and rotor bolts. Basically I would like to get some preload back on the rear and I am not happy with the 5mm drop thru on the forks so I figure If I can get some extra 20mm length on the front I can reclaim the 5mm drop thru on the front and adjust the rake to bring the trail back down with the rear shock adjustment, I hope I have explained this well enough and would love any advice or constructive criticism, Thanks
 

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Discussion Starter #524
the front forks are dropped thru the top clamp by 5mm and this has given me a rake of 22.5 degrees and the trail is 85mm
I don't think you are at 85 with a rake angle of 22.5 - by my math that puts you right at about the stock 90mm

See post #34 of this thread - http://www.triumphrat.net/sprint-forum/102102-the-definitive-usd-fork-conversion-for-sprints-thread.html#post1195267

Perhaps you're not taking the smaller offset triple clamps into account?

but kept the ST wheel .... had to incorporate bespoke axle spacers, rotor spacers and rotor bolts.
At first read I was thinking "why did you not just use caliper spacers?" but then recognized you used a 2012 donor with Radial calipers (actually you would have required caliper spacers for those also, but not in the sense I was originally thinking :D )

I am now at a stage where the front is just sweet but to a cost of no preload on the rear ..... Basically I would like to get some preload back on the rear and I am not happy with the 5mm drop thru on the forks so I figure If I can get some extra 20mm length on the front I can reclaim the 5mm drop thru on the front and adjust the rake to bring the trail back down with the rear shock adjustment
OK, so you have transferred load to the front but I'm not following a couple of things:
when you say NO preload on the rear, which I think implies you want more? But would the rear end not surely be less loaded, therefor you would have too much? Maybe rather than 'pre-load' you meant you wanted to transfer load back to the rear end?
Regarding the plan, not really following that - if you use longer forks, even dropping them 5mm again, your rake angle will not return to the 22.5 (and I believe you recognize that); is your plan then to raise the rear end up (longer shock/higher preload/less sag) to regain the rake angle, to reclaim your original rake and hence trail? But if you do that, are you not back to square one in the weight distribution differential? All you will have done is raised both front & rear therefor not a whole lot will change.

Is it too much front end sag under braking? Would stiffer front springs help?
The ultimate solution, if you really want to regain some weight distribution (but maintain a similar trail) with longer forks (and thus higher rake angle), would be some custom triple clamps with a greater offset
 

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I don't think you are at 85 with a rake angle of 22.5 - by my math that puts you right at about the stock 90mm

See post #34 of this thread - http://www.triumphrat.net/sprint-forum/102102-the-definitive-usd-fork-conversion-for-sprints-thread.html#post1195267

Perhaps you're not taking the smaller offset triple clamps into account?



At first read I was thinking "why did you not just use caliper spacers?" but then recognized you used a 2012 donor with Radial calipers (actually you would have required caliper spacers for those also, but not in the sense I was originally thinking :D )



OK, so you have transferred load to the front but I'm not following a couple of things:
when you say NO preload on the rear, which I think implies you want more? But would the rear end not surely be less loaded, therefor you would have too much? Maybe rather than 'pre-load' you meant you wanted to transfer load back to the rear end?
Regarding the plan, not really following that - if you use longer forks, even dropping them 5mm again, your rake angle will not return to the 22.5 (and I believe you recognize that); is your plan then to raise the rear end up (longer shock/higher preload/less sag) to regain the rake angle, to reclaim your original rake and hence trail? But if you do that, are you not back to square one in the weight distribution differential? All you will have done is raised both front & rear therefor not a whole lot will change.

Is it too much front end sag under braking? Would stiffer front springs help?
The ultimate solution, if you really want to regain some weight distribution (but maintain a similar trail) with longer forks (and thus higher rake angle), would be some custom triple clamps with a greater offset
You are probably correct in saying that the trail is closer to the stock 90mm as the front feels perfect but I used the online trail calculator at rbracing-rsf.com which came out at 85mm when I put in the physical measurements,
as I have been frequently adjusting the set up over the last couple of years and without taking the fairings off on level ground this time the physical measurements came out with three seperate calcs between 90mm and 95mm, I have properly measured the trail a few times but as I said I am frequenlty adjusting the set up on a 'ride and see' basis and for a quick check with the fairings on and also on rough ground was not the most accurate so the online calculator was the easiest option, although once I have stopped adjusting I will do a proper physical recording, however with the rake and trail as it is (whatever the calcs work out to be) I am happy with this final adjustment on the front, just a shame about the 5mm drop thru which looks a bit crappy.
The Busa clamp offset is 32mm.
Yes I did use the readily available honda caliper spacers to accomodate the ST rorors.
Apologies for not being so clear as to what I am seeking and so it is this, I would like to lose the ugly 5mm drop thru on the front and I have got the hagon replacement rear shock and in order to achieve the current satisfactory front end rake and trail set up I have had to wind off all pre load on the rear shock to lower the rear end and in fact I have only just got enough tension on the coil over spring to stop it rattling around and no preload. and since I wound off the little pre load I have a clunk when I go over a bump, I am thinking that if I can raise the rear with some preload it would prevent bottoming out, but would change the rake so some additional length on the forks would bring the rake back and I could lose the ugly drop thru, am I right in this assumption?
 

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Hi there!
I don't want to read all 53 pages. I would like to switch for Busa forks but I wonder if I must change triple clamp or if it do fit with the OEM, that's not really clear in the first few pages.
Also, can the Triumph wing can be easily fit?
 

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i'm strongly considering this upgrade, but a little concerned over fork length, and the reduced offset,
i measured the stock ST forks last night, and from center of spindle to top of fork i make it 750mm maybe 745mm it was hard to be exact as the forks are still mounted to the bike.
this puts 'busa forks 20mm shorter, which would explain why some people are concerned over the side stand,
i have foudn with some of our wonderful speed bumps that the current ground clearance can be a bit marginal, especially 2 up with luggage,

maybe the best compromise would be a custom top yoke, which is not very expensive, this could have a step-down incorporated, a little like the stock ST yoke (once the clip ons are removed)
this would enable the fork tops to be ~20mm lower than with a TL yoke,
however this does not solve the offset.

DEcosse, do you know of a bottom yoke, with more offset that could be used? hopefully it would have a compatible stem, but that could be modified if needed,
the fork spacing is not a issue if we assume a custom top yoke,

another benefit for the custom top yoke is the ability to get the lock position exactly correct, and perhaps even include mounting points for raised clip-on style bars,
 

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Is there a direct replacement option through Ohlins or some other company that is just a swap out for the OEM but with USD forks? I realize this would be major $$$$, but was just wondering if it was an option or not or even if you got custom Ohlins, it would still require all these mods.
 

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Ok, after time-assassinating Ken to death over PM (thank you so much man), I bought into this endeavor. Ordered a Hayabusa front end and some other bits for the ergos. I bought silver ones basically because the set up was only about $150 shipped, and the bike's silver anyway.

Still need to get bearings, spacers, fender, etc. It'll be a good project while I slowly get the new-to-me 2003 sorted to my liking over the next couple of months.

Special thanks again to Ken!
 

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Hi all.

Done this conversion on my ST. Has anyone who has done this had any experiences in regards to the steering lock loss that was worrying? I mean the steering turning, no the steering security lock.
 

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tiger 1050 forks/wheels conversion

Hi all, been just over a year since last posted, and the conversion is 99 per cent complete, would love to post photos but seems there is a prob right now with uploading images, so hold tight, pics of my gorgeous sprint will follow once techy issues sorted
 

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Oddly, if you use tapatalk (app), you can upload photos still. Not sure why, but it works. Would be great to see your photos.

Sent from my SM-G950U using Tapatalk
 

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Ok, I've been a few rides now and the bike feels ok. Have the people who have done this conversion, that have also retained the standard fork length of the Hayabusa forks, changed the springs for others that have either a higher or lower rate. I went on the race tech site and it recommended a high spring rate. I was think I may need to go to a lower. Since I didn't do a lot of kms's (really not a lot) before I did this mod I don't really have any memory of how the bike behaved before.

Also since I've stripped my bike down maybe there is also a weight difference that might be contributing to other changes in the feel.

I know these questions are quite vague however I'm just wondering how in depth I go before I start to move forward.
 

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Do you have a reputable suspension guru near you? They're worth their weight in gold. Maybe the first thing to.donis freshen up the fork oil though.

Fwiw, they recommend a 1.0 spring for me... 195# dressed and I would agree.

How does the bike feel?

Sent from my SM-G950U using Tapatalk
 

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My Busa USD conversion on my '05 ST 1050

Through superb help from this thread and contact with DEcosse I finally got my conversion done! These came off a 2000 Busa and instead of finding a TLS top triple clamp I cut off the bar clamps, sanded them down and had them powder coated. I drilled 1/2" holes for standard risers at 3-1/4" spacing. Doing this allowed me to keep the Busa vibration dampening (the top cap is connected to the triple clamp with rubber isolators). There were lots of small things that Ii needed to do, of course, but all in all the instructions were great... just be prepared for a big job, not a small job..and lots of trips to the internet and store for parts, but there you go.. and I rebuilt the forks while I was at it and installed a Wilbers rear shock... but today, it's raining in Las Vegas, so I can't ride it... grrrrrr.. in Vegas.... sigh..









 

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I'd be interested in your fork rebuild. I need to up my springs and do an oil refresh and I heard you need to either buy or fab some tools

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Well, took 'er for a spin through Lake Mead National Recreation Area to RedStone and back... it's a completely different bike! Before, the wallowing limited how I rode, now it's just me limiting it!

WOOT!


 

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Great how-to on the inverted fork servicing. It is only very slightly more involved than a conventional fork service, which I've done a few times before.

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