R1200R forks into an R1200RS

[grant90]

Has any one put the forks from the R into their RS to see if it speeds up the handling a little ?

[dirtrider]

8 hours ago, grant90 said:

Has any one put the forks from the R into their RS to see if it speeds up the handling a little ?

Morning grant90

 

I haven't tried but usually a new front tire with a more triangular profile will put little perk in the side step. If you have a worn front tire that has a flat wide center band that will make the handling sluggish. 

[Toruk]

Only the bottom section is different.

[grant90]

i am well aware as I have both bikes....just wondered if anyone has done the change....and  yes the tyre makes a difference.

[JCtx]

That's what the RS should have had from the factory IMO. It never made any sense to make the supposedly sportier RS lazier than the R. But I don't think you can just change that lower fork part; you'd have to change the entire forks, I think, but would be great if I'm wrong. My R handles awesome for its weight, but haven't ridden a 1250RS to compare. I honestly don't think it's worth messing with that; the difference should be very minor.

[duckbubbles]

Looking up the spec's for both bikes I found:

Same steering head angle 62.3 deg., 27.7 deg, (US style of measurement).

R trail 125.6mm, 4.94 in.

RS trail 114.8mm, 4.52 in.

 

I have always believed (am I wrong?) that more trail increases self centering of the front wheel and slows steering response.  Choppers back in the day must have had trail measured in FEET.

If that is so, installing a set of RS forks on an R would speed up the steering response and R forks on an RS would slow steering response.  You can reduce trail enough that you run into stability problems. 

Could it be that BMW reduced the trail on the RS to more closely match the handling of the R?  I haven't ridden an R so I don't know.  Also, the RS has a narrower handlebar so you have less leverage on it than the R handlebar.  I recently installed a Wunderlich tubular style handlebar on my 23 RS.  Worked fine but I didn't like the extra width of it so I took it off.  Maybe I didn't give it a fair trial before I switched back.

Looking at the pictures, it appears to me that the RS fork should have MORE trail than the R.  Can someone explain why that isn't so?

 

Frank

[Paul De]

Not sure if this helps, but if you have an aftermarket shock on the rear, you might be able to increase the shock length a little, which would reduce both rake and trail.  When I installed Öhlins shocks on my Oilhead RT, I increased the rear shock length a little and it helped improve steering quickness. I was too conservative and should have added more length, as steering did get a tad quicker, but It could have been a bit more.  In any case steering quickness improved even with several mm of added length.
 

In the wayback days my ‘83 GPz  had an eccentric drive chain adjuster and specified the axle hole rotated from 11to 1 o’clock.  I flipped the adjuster to so that the axle hole rotated from 5-7 o’clock in the adjuster which raised the rear of the bike almost a full inch.  That changed a slow handling GPz into a much more flickable handling machine.

[JCtx]

5 hours ago, duckbubbles said:

I have always believed (am I wrong?) that more trail increases self centering of the front wheel and slows steering response.

That's only when the center of the front wheel is aligned with the forks, which is almost always the case. And it is with the R, but not the RS. Pushing the front wheel forward also increased the wheelbase (besides changing the steering geometry). Testers who rode both back to back claimed it was quite obvious the R handled better, with quicker steering (they called the RS 'lazy'), but I bet the difference is probably not that great. Plus it could also in part be due to the handlebars being wider than the clip-ons. The handlebars on the R feel perfect to me, and effortless to turn, but it's a matter of personal preference, I guess. Anyway, I have a 2-day camp at Barber later this week, so we'll see how I feel the S1000RR by comparison to mine this time around. Two years ago in Laguna Seca, the clip-ons felt too narrow initially (and much lower, of course), but I didn't have any issues, since they're only 20-min sessions. But this time I'm 2 years older (62). Ha ha. I needed more effort to corner, but I was going at a much higher pace than I can on mine. We'll see this time, since I want to push even harder, but it'll depend if my shoulder and elbow cooperate. They feel fine now, but when pushing that hard, they could bother me, forcing me to slow down. We'll see. Just hope I come back in one piece. Ha ha.

[grant90]

On 7/15/2024 at 5:11 PM, JCtx said:

 But I don't think you can just change that lower fork part; you'd have to change the entire forks, I think,

That was the question - changing the whole forks - which is much easier than having to pull them apart to change just the bottom part..one only has to drop the wheel out, drop off the calipers and disconnect the leccy part to the top LH fork.  I was just curious if any had done it...not that i can feel much difference in steering between my R and RS - but they have different from tyres on them...pirellis on the R and Metzelers on the RS.

[JCtx]

Hey, if you have both bikes, give it a try, no? And you'd be able to know for sure what the differences are, by riding both. But if you had to spend the money to do it, I honestly don't think it'd be worth pursuing. At least not without knowing the difference they'd make. Invite a buddy to help you swap them, and give it a try. Now I'm curious to hear from an actual owner of both, what difference that change makes. Ha ha. Good luck.

[Paul De]

Looking closer at the RS fork assembly, isn’t it possible to drop the triple clamps down several mm on the fork legs. Quick and easy to speed up steering.  It appears the triple clamp offset isn’t a lot so the handle bars would limit the distance the fork sliders could be raised in the triple clamps, but a few mm might be enough to get the result you want without a wholesale swap of fork assemblies. 

[grant90]

5 hours ago, JCtx said:

Hey, if you have both bikes, give it a try, no? And you'd be able to know for sure what the differences are, by riding both. But if you had to spend the money to do it, I honestly don't think it'd be worth pursuing. At least not without knowing the difference they'd make. Invite a buddy to help you swap them, and give it a try. Now I'm curious to hear from an actual owner of both, what difference that change makes. Ha ha. Good luck.

 yes it is something  I might do , it isn't that difficult - but i asked in case anyone had already tried it :-)

[dirtrider]

6 hours ago, grant90 said:

 yes it is something  I might do , it isn't that difficult - but i asked in case anyone had already tried it :-)

Morning grant90

 

You might try a steering damper disconnect before going after suspension angles. 

 

I don't know how the newer boxer bikes react but on (some) older R & RS bikes the steering damper hindrance was quite noticeable. 

[duckbubbles]

10 hours ago, Paul De said:

Looking closer at the RS fork assembly, isn’t it possible to drop the triple clamps down several mm on the fork legs. Quick and easy to speed up steering.  It appears the triple clamp offset isn’t a lot so the handle bars would limit the distance the fork sliders could be raised in the triple clamps, but a few mm might be enough to get the result you want without a wholesale swap of fork assemblies. 

That is an option, BUT-  the sidestand on many RS's lets the bike stand up almost too much vertically as it is so doing that would make the situation even worse.  Have to be very careful when parking to put it at an acceptable angle.  Any lowering of the suspension is probably going to involve shortening the sidestand.  

 

Frank

[Paul De]

Hmm,  right hadn’t considered that.  I’ve found most of the R model side stands are too long and if running the suspension on soft or the bike is loaded it sure can be precarious perch.  On my RT I lean toward using the center stand most of the time but a lowered front triple clamp may make the lift onto it difficult.