I’m not a lawyer, but the patent does seem to be quite specific about flat surfaces with roller bearings between them.

Of particular importance are axially extending longitudinal flat sections or “flats” which are provided on opposing surfaces between the two tubes, along with a plurality of free floating needle bearings disposed on these flat sections to all but eliminate stiction

Linkage forks have been tried on motorbikes too. Like every solution in engineering there are pro’s and con’s and I think the cons of linkage systems simply mean the overall net benefit is not there, apart from weight, cost and complexity, a downside to linkage setups are poor feedback, which is quite important on a mountain bike to give the rider confidence.

My experience on the Lefty was that the fork was noticeably stiffer and the performance/activity of the suspension under braking – which I’d never really felt before as stiction increases with conventional bushed forks so they don’t work as well under braking. This gave me a lot more confidence under braking on choppy surfaces. Something I miss with my current Pikes.

However the Lefty did suffer a lot more braking dive than a conventional fork because of the lack of binding up of the fork action. OK you can easily compensate once you’re used to it by moving your weight rearwards when braking to use weight to counteract it, but then you’re unweighting your front end at a time you want to weight it up.

So on balance there were overall benefits to the lefty, but they do have their disadvantages too.

However the Lefty did suffer a lot more braking dive than a conventional fork because of the lack of binding up of the fork action

But that should be addressed through damping and spring rate/progression.

nickc – Member
Mountain bikes is a fashion industry. You can tell this, as it has “model years” and is driven by lifestyle images, marketing, and advertising.

Lefty forks aren’t fashionable right now. When they are fashionable, they will be on bikes.

Woohoo maybe I’ll be fashionable one day!.

Boing Boing

But that should be addressed through damping and spring rate/progression.

True, but the damper on my lefty wasn’t that clever. It was a PBR damper so couldn’t independently set up low speed and high speed compression damping. It basically had lockout and a single knob for setting rebound damping. And in anywise how would you set up your low speed compression to address brake dive? You’d want to set it high, but then that would compromise the normal suspension performance where you would want it set lower. Brake dive is too slow for high speed compression damping.

I liked the lockout though. It would automatically disengage if you forgot to unlock at the top of the trail when as soon as you got a couple of biggish hits in. Not sure why all shocks don’t have this feature. It worked well on the lefty and I really don’t use shock lockouts now because I invariably forget to unlock at the top of the climb.

I’ve always wanted a lefty

Or an AMP Research fork

I like weird designs 🙂

Been following this thread as I too have long hankered for a Lefty fork, especially for my sexy skinny Salsa A La Carte 8)

ChunkyMTB – Member

Woohoo maybe I’ll be fashionable one day!.

Boing Boing
Peng

What about the VN Revelstoke? I know its not suspension but still using the Lefty design.

I’ve got a lefty and view it as a conversation starter rather than a performance enhancer.

The suspension action is great but I find it a bit flexy when the going gets rooty and rocky.

I think the needle roller bearings are the crux of this design. Wouldn’t be surprised if they came up with that first, then found it really heavy, then realised they could do away with one leg.

I’ve not ridden one, only squished, but they are extremely sensitive to small forces.

When will we get leftys for the rear wheel?

molgrips – Member

I think the needle roller bearings are the crux of this design. Wouldn’t be surprised if they came up with that first, then found it really heavy, then realised they could do away with one leg.

You wait, come 2025, we’ll all be rocking lefty derived needle bearing dual leg single crown USD forks with oleo strut damping.

Boosh, back of the net!!

The headshock suspension systems used the ‘roller bearings on flat surfaces’ prior to the lefty. I think the headshock design was constrained to limited travel, which is why lefty was developed.

Both headshok and lefty are stiff than a conventional fork.

And don’t forget that the USE linkage design USP was antidive.

Also, I had the idea for needle roller bearings with square tubes in the early 90s. Didn’t do anything with it though 🙂

I’ve always thought there was more room in the market for leading link style forks with rear shocks allowing you to swap and change suspension but the complexity, cost and people’s inability to see past a design 20 years old seems to be a stumbling block.

It’s a few decades more than that. They’ve tried all sorts with motorbikes. The solution that works best is what we’ve got. Anything else is just a novelty (and worse).