Forks swap-- ATE's to Brembo's---can I do this?

[p2squared]

Here's what I'm wanting to do on my '74 R90S Cafe Bike--
Currently have the forks from a /7 Dual Disc ATE calipers & wire spoke wheel.

I'd like to switch over to the forks from my parts bike, '83 R100CS with Brembo
Brakes. It was fitted with the Snow Flake wheels (believe replaced in recall w/
good ones).

My questions:
-can I just pull the forks from the upper & lower tripple clamps
and slide in the ones from the CS? Or if the upper/inner/chrome
part of the forks that go in the triple clamps are the same size,
would it be better to just replace the lowers with the ones with the Brembo tabs?

-wondering if the axle is same size for Snow Flakes vs. Spokes?

And if not, I could be in the mood to switch wheels as well, and like the 'Flakes
in that they're tubeless.

But---in trying to keep things as light as feasable, I had checked the
weight of my spokes front wheel w/tube & tire vs. the Snow Flake w/a tubeless
tire mounted, and spoke wheel was still a few lbs. lighter, which is why I'd lean
toward keeping spoke wheel.

Any body with experience or thoughts on this?

Thanks in advance.

p2

[khittner1]

P2---Yes, the later fork assembly can be transplanted to an older bike. No, your '74 spoke wheel/axle won't work with a later Brembo-equipped fork---you'll need a '75 or later spoked wheel with the larger axle. And snowflakes were not originally intended to be run tubeless---BMW put inner tubes into those wheels at the factory. This latter topic has been extensively discussed for years, though, and some "experts" disagree on the need for inner tubes. I run tubes in my '84 RT's snowflakes and I can't be cajoled into doing otherwise. Opinions will probably differ, though.

[melville]

Is it too early to call dibs on your dual disc ATE forks? I'm looking to upgrade from a single ATE.

If you are using later forks and not 1974 originals, your axle will be compatible at 17mm. You'll need another wheel if I'm remembering the compatibilities, something with a narrower hub if it's a spoked wheel.

[Duane Ausherman]

Did you weigh the 74 spoked wheel with the discs installed? They are very heavy and really mess up the handling of the "S" bikes.

[bbelk]

Is it too early to call dibs on your dual disc ATE forks? I'm looking to upgrade from a single ATE

I am willing to share with Melville. Give him the left side and I will take the right.

[khittner1]

Sorry, P2---I overlooked the "/7 forks already on the bike" note in your original posting. There won't be axle size issue in that case. Dunno about the hub width issue raised by Melville.

Similarly, I don't know whether Duane is suggesting that the drilled dual rotors of the '75 and later bikes are better/substantially lighter than the '74's original solid disks, or whether its the weight of the second brake rotor, drilled or solid, that he thinks is problematic. I've had two dual-rotor 90S-es, and a single-rotor 90/6, and I don't remember there being much handling difference between them, though I wasn't pressing the handling envelope with any of them.

[Major Softie]

Sorry, P2---I overlooked the "/7 forks already on the bike" note in your original posting. There won't be axle size issue in that case. Dunno about the hub width issue raised by Melville.

Similarly, I don't know whether Duane is suggesting that the drilled dual rotors of the '75 and later bikes are better/substantially lighter than the '74's original solid disks, or whether its the weight of the second brake rotor, drilled or solid, that he thinks is problematic. I've had two dual-rotor 90S-es, and a single-rotor 90/6, and I don't remember there being much handling difference between them, though I wasn't pressing the handling envelope with any of them.

It's the weight of the cast wheel he's talking about.

[khittner1]

If so, I haven't experienced handling problems with my snowflake-shod RT that I would attribute to the somewhat greater weight of the cast wheels. But I must be going way too slow---the OE fork springs and Nivomats do let my old steed float along like a mid-80s Cadillac . . .

[p2squared]

Thanks for all the feed back and info.

So, yeah, got the later model spoke wheel that fits already on it (w/the /7 forks mentioned above).

Measured the width between discs and exactly same as on Snow Flakes & my spoke wheel. So far, so good.

Now, 2 more questions:
-inspecting the forks from my '83 parts bike, notice some pitting in the chrome upper part of the fork,
so hoping can swap out the ones from my /7 forks, you suppose?

-go with the rubber gator accordion style fork protectors vs. the small hard rubber ones that are on the
CS forks now? Seems I recall they do a better job keeping dirt out, right?

And, I do in fact have 2 sets like new, forks for the dual disc set up ATE brakes I need to sell. Make a fair
offer. Located in Monterey, CA. drop an e-mail if you're interested.

And thanks for all the good input.

p2
pvp1@mindspring.com

[Major Softie]

Yes, fork gaitors do 100's times better a job of protecting the fork legs. Along with being much better at keeping out dirt, they also protect the fork tubes from bits of gravel and such thrown up by vehicles in front of you, which often will cause a nick that makes a fork seal start to leak.