Track offset

[Huzo]

Today I was looking through a friends workshop manual for his R1100S BMW. I noticed that there is a design feature that allows for a 5mm track offset between the front and rear wheels. When viewed from above facing forward, the front wheel track sits 5 mm to the right. Does anyone know the real reason for this and does the Norge have the same feature. I wondered if it was designed in to counteract the possible tendency for the bike to pull to the right under power due to torque reaction, but then that would work in reverse under trailing throttle, so I thought that was probably a bit lame as a reason. Dunno.

[oldbike54]

 I think that is for sidecar purposes .

 Dusty

[Huzo]

OK Oldie, that's a start.

[tris]

That'll be a bit of a challenge for those of us that ride on the correct side of the road as it would make the handling with a sidecar fitted worse

[oldbike54]

That'll be a bit of a challenge for those of us that ride on the correct side of the road as it would make the handling with a sidecar fitted worse

 We don't care about you guys  Seriously , I read somewhere that was the reason .

 Was it a Scandinavian country that had traditionally driven on the wrong (left) side whose gov't decided to change over to driving on the right side and simply announced the change one day . Seems there was no training or preparation , just , "OK folks , change sides , and good luck" 

  Dusty

 PS , a quick check says it was Sweden .

[Huzo]

Ok let's run with that, for now...... How would purposely running the two wheels out of track assist in the handling of an outfit?

[Huzo]

Well Roadie to answer your last question about "who cares", I do. Now if you want to read the opening post you'll see that the discussion is why would a mob with the design cred of BMW, purposely set the front wheel of anR1100S off to the right by 5 mm ? Just asking.

[Huzo]

There's a specific part in the manual that shows 5 mm to be a requirement. If you don't care, don't answer, if you don't know, then that's something we have in common. Don't you reckon it's an odd feature to design into a vehicle that is supposed to run on a single track ? And as far as I know a feature is a characteristic that something possesses, and not necessarily a desireable one. I've been in these slanging matches on the forum in the past as I expect have you. I just thought there might have been someone with enough knowledge to give an answer.... But not yet.

[kingoffleece]

Sounds like a question for Kevin Cameron.

[Huzo]

I don't know who Kev Cameron is, does he have a good knowledge of these things in particular? Just that some things you know must be done for a damn good reason but other than one vague possibility,I can't imagine why.

[fotoguzzi]

I thought BMW advised not to put a sidecar on any of there modern bikes?

[kingoffleece]

http://www.cycleworld.com/tags/ask-kevin

This is just a taste.  Google him.  Get BIKE from the UK.  Get his books.  A wealth of interesting information with the world class racing experience to back it up.

[sib]

We don't care about you guys  Seriously , I read somewhere that was the reason .

 Was it a Scandinavian country that had traditionally driven on the wrong (left) side whose gov't decided to change over to driving on the right side and simply announced the change one day . Seems there was no training or preparation , just , "OK folks , change sides , and good luck" 

  Dusty

 PS , a quick check says it was Sweden .

Yep, Sweden, 5 am on Högertrafikomläggningen, (H-Day), September 3, 1967.  Everyone seemed to survive.

[sib]

I have a related question.  My '16 V7II Stone pulls slightly to the right when I remove my hands from the handlebars.  I never noticed that happening on my previous '13 V7 Stone.  It doesn't seem to be related to whether the road is crowned.  There's no binding in the steering.  I tried shifting my weight around in the saddle and it doesn't seem to affect this phenomenon, so I'm concluding that it has something to do with wheel track misalignment.  There's nothing in the service manual about wheel track adjustment.  Does anyone have any advice or pointers?  Thanks.

[swordds]

Google "BMW motorcycle front wheel offset" and a lot of discussion comes up, including a lot of info about pull to the right syndrome and offsetting the front wheel to correct it. Even some discussion that it is necessary to correct for frame misalignment, particularly with K bikes?  Also some discussion about uneven and premature tire wear caused by pull to the right syndrome and correcting it by carefully centering/aligning the front and rear wheels. Funny that there is nothing said about pulling to the left?  Always to the right only? 

[tris]

We don't care about you guys  :grin:

I'm really hurt now 


Don't the short track oval guys over in the US run funny asymmetric tracks so the car wants to turn left all the time

Similar ....... but opposite effect

[acogoff]

   It seems to me the difference in sets of tires and steering head condition- adjustment would have just as much or more effect on directional control. As long as I can point the thing in the general direction and after a while arrive there with ease I am happy.(insert one of Chuck's shrugs here)

[Guzzistajohn]

I got snarky, Huzo.  Sorry about that.

Nice of you to apologize David, I thought you had been to the proctologist 

[Mike Tashjian]

I think the ABS shimming on the BMW might account for some allowable adjustments.  I know the ABS sensor on my 04 rear wheel is not shimmed but the wheel is. Some models show shims on the ABS sensor. Really any company that can justify fifteen pages of instructions and nine bleeder nipples to bleed the brakes is not doing anyone any favors. And to top that off the ABS unit is more than a couple of grand if it craps the bed.  I really like my Guzzi for it's simplicity.  The wife really likes the way the BMW rides, so two bikes or more it is.   Mike 

[oldbike54]

 What's ABS ? I'm hurt you guys don't like my sidecar idea  Oh , lots of modern beemers are pulling hacks , especially the ugly R1200 C .

 Dusty

[kirby1923]

I think the ABS shimming on the BMW might account for some allowable adjustments.  I know the ABS sensor on my 04 rear wheel is not shimmed but the wheel is. Some models show shims on the ABS sensor. Really any company that can justify fifteen pages of instructions and nine bleeder nipples to bleed the brakes is not doing anyone any favors. And to top that off the ABS unit is more than a couple of grand if it craps the bed.  I really like my Guzzi for it's simplicity.  The wife really likes the way the BMW rides, so two bikes or more it is.   Mike

Ha! Don't ever let her ride on a Goldwing! (but I've heard that they (Gw) are easier to work on than a Beemer.

:-)

[fotoguzzi]

What's ABS ? I'm hurt you guys don't like my sidecar idea  Oh , lots of modern beemers are pulling hacks , especially the ugly R1200 C .

 Dusty

still I think mounting a hack voids the BMW warranty.

[tris]

The off set on the oil head motos are for the ABS rings if you have ABS there is a shim or spacer that is between the hub and the wheel to provide clearance for the rings.

BTW they drive on the left in the UK 'cause the French drive on the right.

:-)

To be honest I think over the past 100 years or so the Brits and the French have got along fine

However, if we vote the "wrong" way on the 23rd June that may all change.

We'll have gun boats patrolling the 25 mile limit keeping French (and Spanish) fishermen out of our waters

Challenging times ahead

Sorry - back on Topic

[kirby1923]

To be honest I think over the past 100 years or so the Brits and the French have got along fine

However, if we vote the "wrong" way on the 23rd June that may all change.

We'll have gun boats patrolling the 25 mile limit keeping French (and Spanish) fishermen out of our waters

Challenging times ahead

Sorry - back on Topic

I have had a place in Paris for many years and what I said is a common laugh!

I agree that the EU thing is quite complicated.

mike

[oldbike54]

 Easy with the politics fellas , we won't solve any EU problems here . Thanks .

 Dusty

[cruzziguzzi]

I don't think that deliberate offset is anything new to motorcycle manufacturers.

While I can't recall a single particular just now, I know that when I was reading a lot of magazines, it would come up quite often, or, at least more than one might think.

Sometimes the classic bike mags would have letters/articles highlighting the frustration with trying to restore a bike to a linear trac and one of the experts would chime in with "no, they have an offset to account for ***".

Sometimes, it would be new bikes wherein an offset would be noted by the evaluators and explained away as coping with an older original design but uprated drive or suspension playing havoc with perfect geometry.

Todd.

[oldbike54]

 Todd , I think in most cases the offset on those old bikes was dealt with by lacing one or both wheels slightly offset to the hub . Lots of Brit bikes came from the factory with an offset rear wheel .

 Dusty

[cruzziguzzi]

Todd , I think in most cases the offset on those old bikes was dealt with by lacing one or both wheels slightly offset to the hub . Lots of Brit bikes came from the factory with an offset rear wheel .

 Dusty

No kidding? I missed that or forgot it completely.

They'd spoke some of them up offset? And I thought tuning a wheel centered on plane and axis was hard!


Todd.

[oldbike54]

No kidding? I missed that or forgot it completely.

They'd spoke some of them up offset? And I thought tuning a wheel centered on plane and axis was hard!


Todd.

 Yep , required different length spokes . Even into the early 1970's Triumph was still using this method . Cheaper than re-engineering the frame and swing arm , or the British bike builders thought so  I was friends with an ex-pat English woman who worked for both BSA and Triumph in the 1960's in the wheel lacing dept . She told me that even with the proper jigs it was still tricky , as the frames tended to vary from one to another , and often times a wheel had to be re-trued in situ .

 Dusty

[kirby1923]

Yep , required different length spokes . Even into the early 1970's Triumph was still using this method . Cheaper than re-engineering the frame and swing arm , or the British bike builders thought so  I was friends with an ex-pat English woman who worked for both BSA and Triumph in the 1960's in the wheel lacing dept . She told me that even with the proper jigs it was still tricky , as the frames tended to vary from one to another , and often times a wheel had to be re-trued in situ .

 Dusty

But wasn't that to bring the wheels BACK in line due to a twisted (for lack of a better term) frame?

Whats going on with the beemer is the wheels ARE off set on purpose to make the ABS ring fit.

 :-)