Ideal front/rear weight bias?

[gschuld]

Most comments seem to be in the weight down low and favoring the rear tire direction.  Is there a general range of successful front/rear weight bias (WITH rider in position)?

Something close to 60 rear /40 front I?d guess?  I can?t imagine a more fwd bias than 55 rear/ 45 front being ideal.

I?ve read of some top sit on bikes ballasting the rear down low significantly for traction, then adding weight fwd down low to achieve a reasonable front/rear weight bias.

So what?s the scoop?🙂

George

[salt27]

I don't have the answer you are looking for but have been told weight placement with a full faring is critical.
Maybe someone in the know will chime in.

  Don

[Koncretekid]

I'd say 50-50 and make sure your center of gravity is ahead of your center of pressure.  Traction is not as important as handling.  A light front end, hit a small bump, and you could get a tank slapper.

How much horsepower do you anticipate? That will determine whether you need ballast.

In any case, build it well and give it a try.  Then make changes as needed.

Tom

[gschuld]

Tom,

I?m looking at around 115 RWHP at sea level N/A, but would like to consider the potential for an extra 30-50hp of nitrous in the fuel class down the line.

FWIW, my buddy with 80 RWHP in the 750 classic class seems to be doing fairly well without ballast traction wise.

George

[Koncretekid]

George,

I'm only dealing with about 50 rwhp, so I don't have traction problems.  But I'm also dealing with partial streamlining and up to 150mph, and side winds wreak havoc on handling, so handling is a priority for me.  115 rwhp may present some traction problems that you can live with (go easy on the throttle!), but remember that some turbo charged bikes are dealing with at least twice that hp and speeds over 200mph, so that is why I suggested you try to get it balanced, which is probably close to stock, and give it a try.

Hopefully, others with higher hp will chime in.

Tom

[gschuld]

Tom,

Yes I can see balance being a big factor.  I?ve read quite a few reports of sudden side winds blowing in mid course from
a gap in the mountains funneling gusts of wind. 

For modified class, the wheelbase gets stretched up to 10%.  So say if that all went out back with a longer wheelbase, the effective weight balance shifts fwd.

So in that case it would seem logical to assume some rearward weight shift of the components or adding some ballast near the front of the rear tire either mounted to the wing arm, lead shot in the swingarm, or mounted to the frame in that area would make sense.  A level of adjustment of weight for fine tuning on the salt seems logical as well.

George

[wobblywalrus]

My bike has the horsepower and swingarm extension length you are discussing.  There has been no need to add ballast.  The 50-50 static weight distribution that Tom mentions is a good idea.