BMW /5 Project

You plan on racing this machine or is it just for pleasure riding?
does the double leading shoe brake have a small axle, the axle on most USD forks is large diameter because the axle is the fork brace

TrialsRider said:

You plan on racing this machine or is it just for pleasure riding?
does the double leading shoe brake have a small axle, the axle on most USD forks is large diameter because the axle is the fork brace

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Too Old to race. Not sure on the axle, but, I have a lathe and mill so that's part of the fun. Any suggestions on forks?

USD forks are fat at the top which reduces clearances and increases turning radius, they are stiffer if fork flex is an issue on your RSU forks otherwise not a lot of up side. Big axle requires a big wheel bearing and that would be difficult to retrofit on an old drum brake. The two would not normally be seen together.
The thing that makes good forks good other then quality of design and construction is extra adjustments for spring preload, rebound dampening adjustment and possibly even compression dampening adjustment although that is less likely.
USD forks might be shorter too. Ohlins sells a Retro RSU fork of very good quality and features if you have deep pockets, they are larger in the stanchion tubes so new triple clamps would be part of that equation.

I plan to compete on trials bike or sidecar to at least 80, they have race classes for senior citizens

Tires are everything, what do you hope to run for tires? Radials kick ass if you can fit them. Good tires is what will test for frame flex, test your suspension and make you go fast around corners or on the wet..

TrialsRider said:

Tires are everything, what do you hope to run for tires? Radials kick ass if you can fit them. Good tires is what will test for frame flex, test your suspension and make you go fast around corners or on the wet..

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I appreciate the tire issue , I love the look of the retro Shinko 270's. having the same diameter front and rear is important to the visual and the tall profile gives it the look. Compromising the railing in corners.

Around here we call those clown shoes, great tire choice if you never plan to ride it and want it to look oddly old. You won't need to spend money on all the engine performance upgrades if you can't put that power to the ground.
Are you building a cafe racer or a bobber chopper?

TrialsRider said:

Around here we call those clown shoes, great tire choice if you never plan to ride it and want it to look oddly old. You won't need to spend money on all the engine performance upgrades if you can't put that power to the ground.
Are you building a cafe racer or a bobber chopper?

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Thanks for the straight shot. I'm going for a cafe. Tires can always be changed, I like the heft of the clown shoe

Is it going to have fenders ?

TrialsRider said:

Is it going to have fenders ?

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Yep. I've always want to try and lay up some carbon fiber, so this is my shot. I'm planning on using the original small tank.

Small tank nothing on a BMW is small.
Is it a toaster tank? ya you would want to keep that or sell it for crazy money.

There was a touring 7.? gal and a towner at 4.? with the SS side inserts.

lol in 1970 when I looked at them in the Sonic motorcycle showroom I thought BMW motorcycles were built for giant people.

oldguy205 said:

Thanks for the straight shot. I'm going for a cafe. Tires can always be changed, I like the heft of the clown shoe

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I'm kind of in agreeance with the tyre comment. They do look retro, but really are not practical unless you are going to be doing straight road riding.

Doing a lot of engine work and then frame work for better handling will pretty much be negated by the tyres - just my opinion.

The tiny 2 square inch area of your bike that connects you to the ground is the last area you should compromise for looks

4.00 is also too wide for the front rim, your rim is 1.85 and you need a minimum 2.15 rim to fit the 15 pound fat tire. You will add about 6 pounds of spinning rubber to the front wheel, & that will make her head shake more going over bumps.

TrialsRider said:

You will add about 6 pounds of spinning rubber to the front wheel, & that will make her head shake more going over bumps.

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It also increases your unsprung weight and can impact brake performance/increase stopping distance. This is not even considering the impact that the non-performance rubber compound will have on the stopping distance.

Also, keep in mind that the dimensions of the tire change at speed and can rub against the frame/accessories if there's not enough clearance. I've got firsthand experience with that.

Are you sure your ride is perfect for the racing? Check the engine thoroughly and don’t forget the tires that made your vehicle a better ride so choose the best one.