DougMcK Posted October 27, 2016 Share Posted October 27, 2016 Hello! I have a 2007 R1200RT, and a '99 R1100GS for comparison. On the highway I prefer the RT in almost all respects. Where I greatly prefer the GS is in the slow or moderate speed tight corners around town, or on slow very twisty roads. The RT just doesn't want to turn in comparison with the GS, and I find myself muscling it around with lots of countersteering force. When I get back on the GS is just seems to know where I want to go! The difference between the bikes is really obvious... I suppose I'm feeling the effects of the extra trail in the RT, so I reckoned I'd check to make sure the pre-load on the front wasn't turned up all the way. Silly me, there's no adjustment... So, I'm now wondering if I need more pre-load in the back to steepen the steering angle a bit. I'm not tall, so I don't want to raise the bike significantly. Any comments from people with experience of this situation? cheers Doug Link to comment
dirtrider Posted October 27, 2016 Share Posted October 27, 2016 Evening Doug Most of the handling difference is in the front tires-- a 17" on the RT vs a 19" on the GS. Not only the tire size but a different profile & different rubber compound. The handlebar position & width are also different. You can quicken your RT up a bit by playing with tire profile. The more V shaped or pointed the tire profile the easier it will turn in. Link to comment
Tri750 Posted October 27, 2016 Share Posted October 27, 2016 Running the tire pressure about 38psi also helps, and as DR said, tire selection can make a big diffence. Example, the Metzeler tire, I can flick by old RT around just fine, but the Michelin PR isn't as quick to respond. Link to comment
DougMcK Posted October 28, 2016 Author Share Posted October 28, 2016 (edited) Hmm. Interesting. For my ride home from work today I cranked the rear pre-load all the way to the highest setting. It made a significant improvement, at least to my taste. The bike was much happier to turn in, and required less handlebar input to keep it tracking on the slower curves. I felt the bike was much happier (I was!), but I shouldn't be having to crank the pro-load all the way up for a single, 150lb rider... Could my rear spring be short/tired? It's got 33k miles? Is there an adjustable front pre-load on any of these bikes? I'd rather lower the front a bit rather than raise the rear. Doug Edited October 28, 2016 by DougMcK Link to comment
DougMcK Posted October 28, 2016 Author Share Posted October 28, 2016 Oh, by the way, the tire pressure is about 37 front, and the front tire isn't flattened in the middle (Michelin PR3). doug Link to comment
Dann Posted October 28, 2016 Share Posted October 28, 2016 (edited) I think your tire pressure is too low. Try running with a higher tire pressure. I keep my 07 at 40 front & 42 rear (T-30 EVO GT) Edited October 28, 2016 by Dann Link to comment
DougMcK Posted October 28, 2016 Author Share Posted October 28, 2016 I'll air them up to 40/42 and try it again tomorrow. Doug Link to comment
RobinW Posted October 28, 2016 Share Posted October 28, 2016 I just finished setting up wilber shocks on mine so front shock is adjustable. I set it for 40mm sag on the front and changing rear preload adjusted over/under steer. I got the rear set to about 25% preload and with one up and no luggage or panniers on the bike, it's perfect. I think as you lift the rear the front geometry changes giving more oversteer, pulls into corners. Maybe your rear shock preload business is showing it's age if you have to have it screwed up tight? Link to comment
George S. Posted October 28, 2016 Share Posted October 28, 2016 Whether it is/was my '03 or '04 RT, my Guzzi, or my maxi scooter, ALL the bikes handled noticeably better with a slight more psi in the tires than is stated on the inflation decals on the bikes. Not more than 2 or 3 lbs over should help. And check those pressures often. Link to comment
DougMcK Posted October 29, 2016 Author Share Posted October 29, 2016 I aired up, as suggested, and the difference was modest, certainly not as much as the increase in rear preload. I feel the bike handles quite a bit better with that preload change and, given that I'm riding solo and am not very heavy, I wonder if this rear shock and/or preload adjustment is tired... If it wasn't so expensive I'd be inclined to immediately try some aftermarket, and adjustable, shocks! Doug Link to comment
George S. Posted October 29, 2016 Share Posted October 29, 2016 IT's unfortunate that it may be expensive, but at least it looks like you may have the answer. Link to comment
RobinW Posted October 29, 2016 Share Posted October 29, 2016 There are a few places over here that rebuild BMW bike shocks. It's significantly cheaper than replacing them. Link to comment
DougMcK Posted October 30, 2016 Author Share Posted October 30, 2016 I've been thinking about this and I'm not convinced the rear shock is sagging. If it was "shot" isn't that mostly going to be a question of the damping, rather than the spring rate changing? In any case, the bike is now higher, as expected from cranking up the preload, and I wouldn't want it any higher than it is right now (I'm fairly short). So, I feel that I'd like to be able to lower the front (and put the rear back to less preload). I really think that, for me, the geometry is preferable with the more upright angle of the front of the bike. (less trail and rake). Does anyone know if the standard front shock should be considered high or low when compared to the aftermarket options? Are there any other adjustments available? Shock mountings, or something...? doug Link to comment
RobinW Posted October 30, 2016 Share Posted October 30, 2016 Doug, I may be wrong comparing what I know to the R1200 shock, but most Beemers use an oil system for preload and a Nitrogen section for the main shock. If the oil has leaked out of the preload device then it will take more ummph to preload it. Look for evidence of an oil leak, look up utube on how to refill yourself. I can't comment on original front shock. Mine is a cop bike and the original shocks had springs like railroad tracks. I replaced em. I did ring Ted at the beemer shop recently and all after market shocks have the same travel etc as the originals if that helps. Link to comment
dirtrider Posted October 30, 2016 Share Posted October 30, 2016 (edited) I've been thinking about this and I'm not convinced the rear shock is sagging. If it was "shot" isn't that mostly going to be a question of the damping, rather than the spring rate changing? In any case, the bike is now higher, as expected from cranking up the preload, and I wouldn't want it any higher than it is right now (I'm fairly short). So, I feel that I'd like to be able to lower the front (and put the rear back to less preload). I really think that, for me, the geometry is preferable with the more upright angle of the front of the bike. (less trail and rake). Does anyone know if the standard front shock should be considered high or low when compared to the aftermarket options? Are there any other adjustments available? Shock mountings, or something...? Morning Doug The spring rate can't/won't change with usage unless the spring sags so much that it the end coils go into coil bind (that won't happen at normal ride height)-- the spring RATE is based on spring wire diameter & number of coils (that never changes with age or wear) Now the spring load (or loaded height of the spring) can change with long term usage. On lowering the front-- I'm not exactly sure that you will get you the desired results by lowering the front of a telever equipped motorcycle. From some of the data I have seen on the BMW telever system it actually increases rake slightly for the first inch or so of travel as the lower control arm is going through an arc (opposite of a conventional fork system) Without putting the 1200RT on a flat surface then pulling the front down in a precise manner it is difficult to say for sure but before spending a lot of time & money on a lowered front spring it might pay you to put an inclinometer on the front fork tubes as you pull the front down a couple of inches or so. Added: I see that the front trailing arm (control arm) is a different part number between the GS & RT-- I wonder if they are different lengths (in the correct direction) & if so IF they will interchange on your 1200RT? --Might just be for the different front tire sizes???? Edited October 30, 2016 by dirtrider Link to comment
lkraus Posted October 30, 2016 Share Posted October 30, 2016 (edited) A couple thoughts: The wider handlebars on a GS will give better leverage and require less turning effort than any RT. When handling is critical, I make a conscious effort to maintain my "Master Yoda" posture, concentrating on removing all body weight from the handle bars. Leaning on the bars may not be the issue here, but can be a factor worth considering. Edited October 30, 2016 by lkraus Link to comment
DougMcK Posted October 30, 2016 Author Share Posted October 30, 2016 Ikarus, Thanks for the comment. Yes, the GS bars are wider, but I'm 100% convinced that I'm not mixing these factors in my mind. At the lowish speed corners I'm talking about I could steer the GS with my knees, or yoda-like mind control alone. D.R. That's a vary good point about the telelever geometry. I probably should spend some time with the bikes side by side doing some careful measurements. Like many things, I suspect that these measurements are easy to do (badly), and more time consuming to do really well... I was driving the RT around yesterday, paying close attention to the steering, and I found one slow-speed corner that the bike really seemed to want to turn in to. It had a large a mount of positive camber. I'm inclined to learn more about the design of suspension geometry (this must all be well-known to the designers), but it felt to me that I was feeling the effect of a larger trail. Perhaps this is just a milder version of the "flop" that afflicts bikes with excessive rake. Doug Link to comment
tallman Posted October 30, 2016 Share Posted October 30, 2016 Ever been to a police rodeo? Really shows what an RT can do wrt slow speed handling. Can be inspiring, eye opening. For most/some of us, yes, the dif between the 2 models results in a big dif in handling. But often it isn't the bike. Not meant as anything negative to you, I am not a great slow speed person on the GT, the oilhead was much better for me, but I think it is mostly mental, not the bike. Link to comment
DougMcK Posted October 30, 2016 Author Share Posted October 30, 2016 No offence taken. I don't claim to be highly skilled, but it's not a problem of what I *can* do, it's a question of which I *prefer*. The oilhead GS makes me grin in slow tight corners (mountain hairpins). I think I'm just looking for a way to make the RT handle a little more like the GS. So far, I haven't found the GS to be particularly twitchy at speed, but perhaps if I compared riding fully laden, at speed, in a crosswind, past 18 wheelers, then I'd really appreciate more the extra straight line stability of a bike with more trail... Doug Link to comment
tallman Posted October 31, 2016 Share Posted October 31, 2016 Well if it is that type of stability you want, buy my GT. It is faster than the new RT's (still) and rock steady in all conditions on slabs at all speeds (I've heard of GPS 140+) plus it carries more w/my touring lids, GIVI 52L and Big Mak tankbags. Not to mention SMOOOOTTHH... Being serious, the 2 models (RT/GS) vary wrt those factors and both do great jobs in most areas, each have their advantage, IMO. How great to have both. Best wishes. Link to comment
DougMcK Posted October 31, 2016 Author Share Posted October 31, 2016 Yes the GT is on my list when I decide I need an 11-foot long, 1200lb, 180mph motorcycle... Doug Link to comment
Kerry in Mpls Posted October 31, 2016 Share Posted October 31, 2016 (edited) Yes the GT is on my list when I decide I need an 11-foot long, 1200lb, 180mph motorcycle... Doug I notice that you said "when", not "if". :-) Edited October 31, 2016 by Kerry in Mpls Link to comment
DougMcK Posted October 31, 2016 Author Share Posted October 31, 2016 Yes the GT is on my list when I decide I need an 11-foot long, 1200lb, 180mph motorcycle... Doug I notice that you said "when", not "if". :-) Indeed... Must be a sign... Link to comment
Tri750 Posted October 31, 2016 Share Posted October 31, 2016 So, how many miles are on the RT? What tire are you running, and how many miles are on the tire ? If you've already mentioned this, sorry. Link to comment
DougMcK Posted October 31, 2016 Author Share Posted October 31, 2016 So, how many miles are on the RT? What tire are you running, and how many miles are on the tire ? If you've already mentioned this, sorry. The bike has about 33k miles, I don't know about the mileage on the tires (they came with the bike). They look pretty good, though. No visible flat spot on the front,and the merest hint on the back. They are Michelin Pilot Road 3. Doug Link to comment
Tri750 Posted October 31, 2016 Share Posted October 31, 2016 (edited) Well, if light steering is very important to you, put a set of Metzeler Z8's on it, run the pressures at 38/42 and start looking for shocks as a Christmas present. The Mich will last longer but steer heavier. There's a big deference. It used to be inexpensive to have stock shocks rebuilt but say, Lindemann is close to 5 each. Look at Hagon for probably the least expensive/quality shocks out there. Made in the UK. Most of us don't gave a clue or need for high/low speed damping adjustment that some of the designer shocks have. BUT it will never be a GS. At the dealership people would buy a GS and start trying to make it an RT, Wind protection wise with screens, lips, guards, deflectors, etc. A GS is a GS and an RT is an RT. Edited October 31, 2016 by Tri750 Link to comment
tallman Posted October 31, 2016 Share Posted October 31, 2016 "At the dealership people would buy a GS and start trying to make it an RT, Wind protection wise with screens, lips, guards, deflectors, etc. A GS is a GS and an RT is an RT. " Time after time. Link to comment
tallman Posted October 31, 2016 Share Posted October 31, 2016 Yes the GT is on my list when I decide I need an 11-foot long, 1200lb, 180mph motorcycle... Doug Doug, It is an '03, not the barge that came later. It is a whole lot different than the boxers which I rode from '68 until I got the GT. Living in such a beautiful part of the world anything you ride or pedal has to be a blast. Link to comment
NickInSac Posted October 31, 2016 Share Posted October 31, 2016 I'm curious to know what your suspension sag is now that you cranked up the rear. Touratech is using a GS. But, I think the 30% rule applies. But, I don't know what the RT total suspension travel is available. http://blog.touratech-usa.com/2013/08/06/how-to-setting-suspension-sag/ Link to comment
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