Cafe' Racers - Ride Quality

[Chuey]

I wondered which forum this subject would fit and decided it would go here best.

On my thread about rear drive shock mounts, I've seen some really cool Cafe' Racer pictures. In looking at those pics, I've noticed that some of them have forks from other models of BMWs or even from some other bikes. That led to my wondering how those bikes ride. I would imagine some of the modifications end up not working so well, no matter how cool they look.

The Cafe' Racer that I have made at this point has the favorite riding qualities of any motorcycle I've ridden. It isn't as powerful as some but ergonomically, it is just about perfect for me! It started out as a styling exercise and ended up to be a real pleasure. I didn't really change the engine much and the frame is all the same geometry as stock, which is what I'm used to so it feels fine to me. Laying down a bit more on the bike is the main functional change I've made.

Some of the Cafe' Racers I see do not have rear set pegs. That is something I can be sure I wouldn't like. Once you lean forward, it rotates your position so that the pegs need to be further back. Also, this allows the rider to resist the backward thrust during acceleration with his legs. Similarly, when I see a Cafe' bike that has the bump way back, as if to carry a passenger, it looks like it wouldn't work so well, as that bump is also part of the staying in position when accelerating.

Front end geometry is something that I suspect will be changed on many of the bikes that have different fork/wheel combinations. That could be a can of worms. To some degree, you can get used to some variation in steering feel but I'm curious as to how some of the bikes pictured will handle.

I guess that's just some rambling thoughts on the subject. Anyone else have some?

Chuey

[Zombie Master]

I consider what you are doing as molestation. If you wanted a high performance bike, why don't you just buy one, they are cheap and effective. You westerners have no respect.

[Duane Ausherman]

I feel differently about this than ZM. It is "your bike" and you can/should do what you want, even destroy it.

I have ridden a few cafe bikes many years ago and most are messed up. Very few of the owners knew enough about mechanics, geometry, handling, reliability, comfort, safety or structure to be able to do a half decent job of it. However, it is their bike and that is that. Usually they brought them in because they knew that something wasn't right. Our test ride would reveal that a whole lot wasn't right and they had no clue. I have even had a couple of mechanics return very quickly from a test ride and refuse to ride it.

Of course in those intervening 30 years I suppose that human nature changed and all is well today.

[Rev Light]

I have both a 1979 R65 Cafe Racer and a 1982 R100.

I have often though about transposing the front forks of an R65 onto the R100. I prefer the firmer set-up that my R65 has and I cannot ignore the alloy upper yoke set-up. Interestingly enough, I did measure the ride height of both bikes I own with my weight on them. I measured (well my helpers did) from the floor to the centre rocker nuts and we actually found that my R65 cylinders were slightly higher than those on the R100 with a rider's weight on them - and yes my hands were on the handlebars. Just goes to show that even though the R65 forks are shorter, they have less travel and are stiffer - so in the real world the ride heights are very similar. It also puts paid to the rumour that you should not fit an R100 engine in a R65 frame - infact it might well be a better home for it.

Of course to complete the job, you could fit an R65 swing arm and shocks as well - thus creating the short wheel base of an R65 and keeping everything else from an R100. Of course its a lot more complicated than that - with all the electrics from an R100 being in the headlight shell......Oh, the only reason the R65 shocks are shorter is to accomodate the shorter swing arm.

If I ever had to go down to one bike, I might combine the pair........

Rev. Light

[Frog]

I have seen photos of Chuey's cafe bike and understand that he takes a lot of time to sort and do things right. I think it is great that he is going that route.

I have a stock looking 1973 R75/5, but the more I ride it the more I want to modify it. In reality, it has been modified plenty, as I have custom fork internals, top triple, modern rear shocks, modern braking material, bored to 800cc, raised compression to 10:1, dual plugged, dyna boost ignition and who knows what else I am forgetting. Now I am trying to further improve the braking.

I recently had a chance to ride a 1966 Velocette Thruxton for a day. For those who do not know this bike, it was Velocette's hot rod bike of the era. The stock set up uses non aggressive clip ons and rear sets. While it was not the best set up for long freeway rides, it was absolutely wonderful on all sorts of country roads that I love to ride. When I returned to my euro bared slash five, it felt like such a clumsy position.

I am not going to convert my slash five, as I will continue to keep it looking stock. But I do understand the appeal of a cafe'ed airhead. In my case, I am building a velocette instead:)

[Major Softie]

I believe ZM was at least partially speaking tongue-in-cheek.

My first hint was when he said "you westerners," as he lives at least a few hundred miles further west than Chuey.

[Garnet]

I believe ZM was at least partially speaking tongue-in-cheek.

My first hint was when he said "you westerners," as he lives at least a few hundred miles further west than Chuey.

Do you mean that ZM really is all wet?

[Garnet]

Well Chuey, as Duane said it is your bike, and you should build it to suit your needs/wants. The fork changes that we see in most pics where done to stiffen up the front end and to make use of bigger/better brake systems. By stiffening I am reffering to the lack of flex rather than the firming of ride.

I can certainly feel the need for a less flexible chassis on my airheads, but I lack the expertize to do much about it. You would have to ride a fork swapped airhead to really know if that is the route you wish to go. You have the knowledge to be able to do the math as far as geometry goes on a fork swap, but there is almost no way of knowing how a set of forks designed for a totally different bike are going to "feel" to you.

In the end I may end up on a different ride if I want a lighter, nimbler, better braked bike. For me it will be much less expensive although much less rewarding.

[mattcfish]

Rear sets are a must with clip-ons or low bars. Very comfortable. K forks would be nice.

[tagordon]

Chuey,
The 39mm forks on my R100 Cafe are fine for me, with the mods and adjustments I have made.
Billet top clamp is big improvement over the stamped steel stock clamp.
Solid clamp ons work great, no need for end weights.
Progressive spring with 5/8" pre-load works for my 165lbs.
I'd have to check the records for the exact volume, but I use the maximum recommended volume of 7.5w fork oil.
I like the compression to have minimal reserve when cornering. Just in case there's a bump to deal with while leaning.
The seat bump is most helpful to me when I am shifting my body side to side when setting for a turn. My thigh hits and I can feel where I need to be for the proper lean angle. I don't feel any hard push into the bump during acceleration. Because of my long arms, I am against the bump normally.