Flexy front end: does it matter on the street?

[Syscrush]

Hey gang.

The more I look at my bike as it is now, the less I want to change the looks. But the more I ride it, the more I want to sort out the suspension. I had heard warnings of flex in the forks and triples due to the aluminum lower and the skinny forks on a 600 lbs bike. I have to say, though, that while I hate the damping (rough over bumps, dives on brakes - just the same as any other damping rod setup), I haven't had any problems that I'd attribute to flex in the front end or the frame. I'm a pretty conservative rider on the street, so my interest in upgrading the suspension is more about comfort & safety than about trying to keep up with modern tackle (or braver riders). I want to know that if I need to, I can trail brake on rough pavement without upsetting the bike too much.

Originally I thought that the bulk of the motor & tank would be well complemented by USD forks from a similarly porky bike like a ZX14 or 'Busa - and then I'd get nice 4-pot radial calipers as part of the bargain. But as much as I'd like the more powerful brakes and the better damping, I don't want to cover up my gold boomies with huge rotors, or change the front end geometry. So I'm thinking about having the fork internals replaced with a modern cartridge setup and just doing a re&re instead of engineering a whole new front end (custom triples, axle, wheel spacers, rotor spacers/adapters, etc.)

A buddy of mine is a suspension guru who set up the 35mm front end on a vintage racer BMW (swapped in cartridge internals, custom valved & sprung) that went on to win a championship. I know that he can do the swap, but I'm worried that I'll hurt myself down the line with a half-measure rather than just going with a whole new setup. My concern is that with the damping improved, I'll be up against front end flex as the next weak link in the chain.

What say you? Is this a real problem for a street-ridden bike, or just a bunch of hype?

[EMS]

Hype. !!
But if you want to do something and still keep the original look, you can always consider changing to a period set-up, like a 39mm Prolink front end or a 39mm CB1100F fork or even a VR1000 41mm fork. These changes make the front end stiffer and changes to the geometry are minimal.
But always remember: You are not going to win a Moto GP race with a CBX no matter what you do.
Rider skill may outdo most changes you make on a CBX suspension. What are yo trying to do? Outrun a modern replica racer with a 30 year old bike?? I guess not.

[Syscrush]

Thanks EMS.

I don't want to swap parts just for the sake of swapping them. However, I do want to switch to handlebars and I don't like the looks Randakk's top triple cover (although I do like the idea a lot). So I may well end up having a custom top triple made anyhow, so it's hard to not consider more extensive surgery.

If I were going to swap to another RSU fork, I'd go with something like the Bandit 1200 forks, since they're stiffer still (43mm), readily available, came stock with both 4 and 6-piston calipers (although I prefer 4-pots), and are a cartridge fork that only needs a set of Gold Valves to work quite well.

On one hand: that would be no less work or money than a USD setup, so USD makes more sense. On the other hand: it would work just as well for someone who rides like I do.

So if I do a swap, it'll be a choice between slightly out of place bling vs. a more subtle and period-correct look. I think I can get the damping I want from the stock setup, and my twin-piston CB1100F calipers with EBC HH pads work OK, so despite the appeal of a complete swap, I think that an internals swap is the most likely route for me to take.

Thanks again for the insight & info.

[Syscrush]

I think that this pic shows that a USD setup with radial 4-pots can look pretty good on a vintage bike with old-school wheels:



But a Superbrace, new cartridge internals, stainless brake lines, and some handlebars would make such massive functional improvements vs what I have now, without any of the hassles/expense of getting a mishmash of parts to fit & work together.

[Jeff Bennetts]

But a Superbrace, new cartridge internals, stainless brake lines, and some handlebars would make such massive functional improvements vs what I have now, without any of the hassles/expense of getting a mishmash of parts to fit & work together.

The Superbrace will do nothing but add weight to the frt end, in 30 yrs of being around CBX's I have never heard or seen any benefits that they have provided to an early model CBX.

If you want handlebars, get a USA spec CB1100F top triple and use 81/82 39mm forks with a RaceTech or similar emulator.

[NobleHops]

But a Superbrace, new cartridge internals, stainless brake lines, and some handlebars would make such massive functional improvements vs what I have now, without any of the hassles/expense of getting a mishmash of parts to fit & work together.

The Superbrace will do nothing but add weight to the frt end, in 30 yrs of being around CBX's I have never heard or seen any benefits that they have provided to an early model CBX.

If you want handlebars, get a USA spec CB1100F top triple and use 81/82 39mm forks with a RaceTech or similar emulator.

Nice. The amount of knowledge you and some of the other veterans have between your ears frankly blows me away Jeff.

[Syscrush]

Thanks Jeff. I appreciate the insight on the fork brace. I was warned off of one for my old SV650 as it had 41mm forks which were not particularly prone to flex (although the triples are supposedly a bit flexy). I thought that for a 35mm setup it might make more sense.

I thought about going with CB1100F parts, since I have CB1100F wheels and expect that everything would fit nice & easy that way.

I agree that emulators are a huge improvement over damping rods, but as far as I'm concerned doing a fork swap (even a relatively simple one like the CB1100F triple with with ProLink forks) without also getting good cartridge internals & 4-pot brakes is not a good value proposition. I'd get slightly stiffer forks, and a mount for handlebars. Getting to something with a high-quality cartridge internals is my first priority.

For someone else interested in going that route, there's a set of ProLink forks on ebay now for $45 + shipping.

At that price, it has to be considered. The extra forks and the replacement triples would be cheaper than a custom handlebar mount solution, plus I could have the internals swapped on the '82 forks without taking my bike out of commission.

Some questions about this setup:

1. Do the CB1100F triples have the same spacing and offset as the twin shock CBX? My guess is that it's the same spacing but different offset.
2. What's the length difference between the early and late CBX forks?
3. Are there differences in the fender mounts between early and late CBX forks?
4. How about the gauge panel? I assume I'd need to fab up some mounts to make it work with the CB1100F triple.

Thanks again. I don't think this is the way I want to go, but it would be foolish to rule it out without learning a bit more.

[EMS]

Well, opinions differ. Dismissing a fork brace as having aboslutely no benefit on an early CBX is a bold statement. The handling quirks and shortfalls of a 79/80 CBX are manifold and will not be cured with a fork brace, that's for sure. But a fork brace will stiffen the front end, no doubt. It is definitely the easiest and cheapest way to have at least some improvement in the 35mm front end. If fork braces wouldn't work, they would have been a fade in the market, but they have been around for many years and are still being bought and I know several CBX owners who have them on their CBXes and they confirm some improvement. Me included.

[Syscrush]

I haven't decided for sure yet which way I'm going to go with this, but my god I am looking forward to having SOMETHING done. The garbage aftermarket shocks I picked up with the bike are so awful that they make the stock front end feel pretty good by comparison. Every time I ride the bike, I daydream about taking it out in the spring after it's had its suspension 100% sorted out. :)

[NobleHops]

I haven't decided for sure yet which way I'm going to go with this, but my god I am looking forward to having SOMETHING done. The garbage aftermarket shocks I picked up with the bike are so awful that they make the stock front end feel pretty good by comparison. Every time I ride the bike, I daydream about taking it out in the spring after it's had its suspension 100% sorted out. :)

Our pal FalldownPhil sold me some Works ProRacer shocks that I put on my '80 and the difference was astounding. I had a pair of Progressive emulsion shocks on it prior, with uprated springs and the spring/damping combo in concert with the simple primitive shock design was gruesome. The bike kicked and bump-steered like mad. Good shocks are not cheap but IMO very worth it for the riding experience.

N.

[Syscrush]

Thanks Nils.

I'm still deciding between Ohlins and YSS. I'm looking for something with rebound, compression, and preload adjustment - ride height would be bonus but not required. I'll coordinate with my suspension guy when I've decided which way I'm going with the forks (internals, RSU swap, or USD swap), because he'll definitely be involved in that, too - and he sells both types.

YSS seems to come in at a slightly lower price point for the same features, and the black/chrome look would be a better fit for the looks of my bike than the Ohlins gold. But Ohlins didn't build their reputation out of thin air, and I'm tempted to go with the more proven performer.

[Randakk]

Thanks EMS.

SNIP However, I do want to switch to handlebars and I don't like the looks Randakk's top triple cover (although I do like the idea a lot). SNIP.

What's not to like! :)

[Syscrush]

What's not to like! :)

Sorry brother, looks like I've been caught red-handed! :)

Like I said in the post, I really like the idea, but I don't really care for the look of a doubled-up top triple from the side, or the rounded shape as seen from the top. I think it's a great product, just not what I want for this bike.

I've decided to go with Pro-Link 39mm forks with the internals replaced with a good modern cartridge setup. I'll use a Pro-Link bottom triple and a custom made top triple.

Anyhow, keep up the awesome work, Randakk. I hope to have a chance to ride out to your shop sometime next year so you can give me a hard time about how my custom triple isn't as nice as yours and/or how my Brembo 4-pots look puny next to your Fishhead setup.

[Randakk]

Syscrush:

Funny, I actually sought this product out for the aesthetics as much as the function :)

The polished aluminum looks bitchin' on a silver/black bike like mine. A typical comment I get from people when I show my bike is that the handlebar conversion looks better in person than in pix.

I'm a big fan of "Superbike" bend bars. They work great for positioning me on a CBX for spirited yet comfortable riding.

Anyway, I'm glad you commented on my brakes. That's probably the best single feature on the whole bike! Putting car brakes on a bike (literally!) may not be for everyone, but I'm addicted to the power and "feel" these deliver.

[Rick Pope]

I think that kit looks great. But I may be a bit prejudiced.