[drew5250]

Hi, this is my first post to the forum. I'm not a GSXR owner, but I am doing a K8 GSXR 1000 front end swap on my 2004 Triumph Speed Triple. The stock offset on my Speed Triple is 32mm. The K8 has an offset of 28mm. I realize that the change in geometry is going to affect handling. Does anyone know of any solutions to bring up the offset so that it is as close to 32mm as possible? I know that lowering the front end will bring the offset up a bit, but I'm not sure if that will be compatible with my setup as I am going to put bar risers and a MX style bar. Any advice/suggestions is greatly appreciated.

 

[Just_Nick]

Why not buy a set of forks that offers the correct offset?

http://www.triumphrat.net/memberalbums/data/504/150.jpg

 

[BillV]

Lowering the front end will have no effect on the offset. It's built in to the triple clamp and the only way to change it is to use a different triple or use offset bushings, if the triple supports them (yours doesn't). Others have used the K5/K6 triple (30 mm offset) after machining it for the larger K8 forks. But I've never been comfortable with removing that much material.

What is the Triumph's rake angle? Lowering the front end will lower the rake a bit and reduce the trail, which will make it slightly more responsive and less stable.

 

[drew5250]

The rake angle is 23.5 degrees. There is no perfect option for retrofitting forks, I'm trying to do my best.

 

[BillV]

My first post included a drawing that illustrated the front suspension that was removed for unknown reasons. Here's another that isn't quite as nice but has the same basic info:

Your Triumph's specs seem closest to K3/K4. It's possible to calculate the trail from the rake and offset. See here, for example. But accurate calcs require that instead of tire radius, you need the distance from the axle to the ground, i.e. the free radius minus the tread compression. The compression seems to run about 8 mm but values are hard to come by.

Does your steering head match the Suzuki, i.e. the bearing dimensions and distance between them? It would be a big coincidence if they're the same and I'd think that there would be serious fitment problems if they weren't. I'd really expect that you'd have to use the Triumph triple and modify it as necessary for the Suzuki forks.

 

[Just_Nick]

My first post included a drawing that illustrated the front suspension that was removed for unknown reasons. Here's another that isn't quite as nice but has the same basic info:

Your Triumph's specs seem closest to K3/K4. It's possible to calculate the trail from the rake and offset. See here, for example. But accurate calcs require that instead of tire radius, you need the distance from the axle to the ground, i.e. the free radius minus the tread compression. The compression seems to run about 8 mm but values are hard to come by.

Does your steering head match the Suzuki, i.e. the bearing dimensions and distance between them? It would be a big coincidence if they're the same and I'd think that there would be serious fitment problems if they weren't. I'd really expect that you'd have to use the Triumph triple and modify it as necessary for the Suzuki forks.

All you have to do is find the inner diameter of the upper and lower Suzuki bearings and the outer diameter of the Triumph bearings, and find the proper bearings from companies like All Balls Racing. It's how I swapped GSXR forks onto my VTR.

 

[drew5250]

I really appreciate the information/diagram. All Balls makes ball bearings designed specifically for the Speed Triple to GSXR conversion...and thank god they do. Apparently the stock offset of the Speed Triple is around 40mm, although that information isn't published anywhere. Decreasing the offset will increase the amount of trail, however, I've been assured by a legendary Speed Triple owner who did the conversion that it makes the bike handle much better. He's using K5 1000 forks that have a 30mm offset and said that fork height adjustment (lowing the front end via top triple tree clamp) nullifies the increased trail.