The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: steve hawkins on March 03, 2014, 03:27:54 AM

Title: R65 rake and trail
Post by: steve hawkins on March 03, 2014, 03:27:54 AM

Anyone know what the rake and trail is for an R65?

Cheers

Rev. Light

Title: Re: R65 rake and trail
Post by: steve hawkins on March 03, 2014, 03:51:40 AM

Okay, a bit of a root around the web and I finally have something:

Rake 28 degrees
Trail 3.78 inches (96mm)

Someone write that down somewhere.  Its not easy to find.

Cheers

Rev Light

Title: Re: R65 rake and trail
Post by: Ed Miller on March 03, 2014, 11:34:38 AM

What do you do with the information?

Title: Re: R65 rake and trail
Post by: Barry on March 03, 2014, 11:42:36 AM

I remember reading when the R45/R65's were introduced that they had a slightly different fork angle to the existing type 247's.  Sure enough type 247's are 27 deg rake and 3.5" trail.  That is a slight difference.
27 - 28 deg is the accepted norm for motorcycle rake angle but Tony Foale did some interesting experiments that suggested the accepted norm was not necessarily the only sort of angle that could work.

http://www.tonyfoale.com/Articles/RakeEx/RakeEx.htm


Steve,

He also experimented with trail so maybe some answers in there for your concerns on the R100.

Title: Re: R65 rake and trail
Post by: steve hawkins on March 04, 2014, 02:04:36 AM

Yes I have read it.

He mucks about with rake far more than trail.

But thanks for the information above, it makes sense.

Even the early days the R65 had a reputation for being a bit flighty, perhaps the extra trail was an attempt to dial some of it out.  The R65 still manages to be livelier than the R100, however.

I am still going to push forward as I have been muttering about his for years.  And it will finally shut me up.

Cheers

Steve H

Title: Re: R65 rake and trail
Post by: nhmaf on March 05, 2014, 04:12:12 PM

In my "BMW Boxer from /5" by Andy Schweitzer, it shows the R45/R65 trail figure as 96mm which agrees with your figure.   It does show the steering head angle as 63 degrees, which would correlate with rake angle of 27 degrees (90 - 63).   For the /6, /7, and R80/R100 series through the 80s, it lists them all with steering head angle of 62 degrees and 88mm trail.  For the  /5 series it shows a head angle of  62 degrees and trail is down to 85mm.

I don't know if these figures are 100% accurate, but we do know that the /5 bikes (which were considered the faster sterring, or "twitchiest" depending on your point ov view) had the least trail of the airhead 247/248 series.