Looking at Cannondales right now, the Lefty fork has for years not had any kind of conventional round stanchion tube or a seal to protect the inners from muck. Cannondale used to make a big thing about this, saying that having no conventional stanchion or dirt seals made the fork a whole lot more reactive to small bumps as it suffered from minimal stiction once the needle bearings had bedded in. I’ve ridden a few Lefty’s over the years, and can say I’ve always thought just how reactive they were to small bumps.

So why for the 2013 model range have Cannondale ditched the rubber boot approach, and changed the fork so it has a round stanchion and a dirt seal? I know it’s an upside down design so should be better than a conventional fork in terms of stiction, but why did they do it?

Hybrid Needle Bearing Technology

The new sealed Hybrid Bearing Technology allows Cannondale to get rid of their lower shock boot, which has been a trademark of the Lefty design since its introduction.

Because it’s impossible to seal a square structure, Cannondale have made the new Lefty’s Teflon-impregnated, hard-anodized lower leg round. This means they can incorporate a wiper seal at the bottom of the upper structure. Just above the seal you find what Cannondale are calling a ‘slide bearing’, which is what we commonly refer to as a bushing.

Because the bushing sits in a fixed position on the outer leg and the needle bearings roll into the fork with the inner leg, Cannondale can make a legitimate claim that their fork gets stiffer as the fork gets deeper into its travel. Unlike traditional forks, where the bushing spacing is a constant, in the Lefty the distance between the lower bushing and upper needle bearings increases as the fork moves through its travel. This adds stiffness. Cannondale say it’s this feature that allowed them to bring Lefty to the longer-travel Over Mountain category.

Cannondale also take advantage of the Lefty’s inverted design and new lower seal to incorporate an oil bath, which lubricates both the bushing and needle bearings as the fork moves through its travel.

“Our system takes advantage of the inverted design and fills the cavity [between the inner and outer legs] to create a lubricating oil bath,” said Hanna. “In traditional forks, gravity is taking the oil away from you at all times, and with our system it keeps the oil in place. Essentially, it’s completely encased [submerged] throughout its riding life.”

Setting sag is easier too, as Cannondale now place an O-ring on the lower leg so that sag can be set visually, as with any other fork. Previously, riders needed another person to manually take the measurement.

from Here

How are people finding living with the 2013 Lefty? Is it still a bit demanding of attention or pretty much like any other fork in terms of maintenance now?

not done much with mine and still feels good although its only done 450miles, its probably due a fiddle soon though

I’m actually slightly disappointed with the new design…I’m sure it’s stiffer but one of the great things with the older version was that the wearing surfaces were needle bearings and shim strips – cheap to replace when they wear and as a result, Lefty’s seem to stick around forever… With this new bushing are we not going to get into the same situation with Foxes and stanchion wear, where the whole lower leg needs to be replaced and it’s half the price of the fork?

Fox stanchion wear is dirt getting through the seals and not enough lubrication fluid/ dry foam o-rings inside. It would destroy any stanchion- it is more that you need to keep an eye on the level of lubrication fluid within Fox Forks a bit more than most.

I don’t think stanction wear will be an issue will it? I would have thought that the needle bearings don’t actually act on the stanction itself and that internally they’ll still have a square secion that the needle bearings act on. Surely the circular stanction will simply be part of the sealing system that the lower bushing acts on to seal the system and not take any of the primay load??

If only they made it at 140mm travel for a 29er.

I had the old lefty and didnt so much as look at it in 5yrs and thousands of miles use until the damper popped a o-ring.
Recently got a new 2013 lefty still a lovely responsive fork and the book service intervals are 50hrs bearing reset. 100hrs clean and lube lower gubbins. 200hrs full service and oil change.

Having looked at the parts diagrams they have travel spacers fitted its just wether the wheel will hit the frame that would limit how many you could take out.

Parkesie, I assume you’re talking about the ‘normal’ lefty and not the new Supermax lefty? The new Supermax lefty no longer needs bearing resets. I reset the bearing after every ride on my 2012 ‘normal’ lefty. It’s only a 3 minute job so may as well. To increase travel on the Normal Lefty you don’t remove the travel reducers as you’re taking the travel out of the top of the fork and risk running the wheel into the downtube. To do it properly you take out the damper and cut the bottom spacer to remove the travel from the bottom of the fork. I’m not sure if you can increase the travel on the SuperMax Lefty in the same way. I would love a 140mm 29er Supermax on my Covert 29. It’s a great fork.

Unlike traditional forks, where the bushing spacing is a constant…

Is this true ?
I thought all conventional forks had a bush fixed to the bottom of the inner and the top of the outer, so that as the fork compresses, they get further apart.

To increase travel on the Normal Lefty you don’t remove the travel reducers as you’re taking the travel out of the top of the fork and risk running the wheel into the downtube. To do it properly you take out the damper and cut the bottom spacer to remove the travel from the bottom of the fork

I don’t understand this either.
There’s Axle to Crown measurement and there’s travel.
Removing the travel reducers, not surprisingly, increases the travel, without altering the AtoC.
What does “cutting the bottom spacer to remove the travel from the bottom of the fork” do ?

The travel reducers at the top of the fork are only installed on the 29er leftys and effectively sets the upper bump stop. The lower spacer effectively sets the travel and the length of this is the only difference between the different travel lefty models, apart from the addition of a volume reducer on the shorter travel models. So to increase travel on a lefty you remove the damper assembly, remove the lower spacer and shorten it by the increase in travel you want. I’d have to take a look at an exploded view again to refresh my memory of exactly how it works, but I went around this a few months ago over on the Cannondale section of MTBR Forum. When it comes to Leftys those guys have been there, done it and got the T-shirt.

New 90mm 29er still details reset procedure in the destructions.

I still don’t get this, wobbliscott.
Travel is travel, whether you increase it at the top or bottom.
Do you mean you are increasing the AtoC measurement ?
That will reduce the amount of overlap between the inner and outer tubes when the fork is at full extension, which doesn’t sound like a good idea to me.

Reducing the amount of overlap between inner and outer tubes is not necessarily an issue if the amount of initial overlap at the lower travel setting was in excess of what is required (if that makes sense!)

This is an updside down fork. The lower spacer is about 100mm long. So as the suspension compresses this spacer determines the stop and hence the full travel. If you cut 10mm off this spacer, then the fork will ‘bottom out’ 10 mm further up. This is exactly how Cannondale adjust travel across their Lefy’s, by utilising different length lower spacers.

On 29ers they insert 3 10mm spacers at the top to prevent the wheel clashing with the crown – like an additional upper stop, but compensate with this loss of travel with a shorter lower spacer to achieve the desired travel. My 29er Lefy has 90mm travel and I looked at getting either 110 or 120mm travel but I didn’t go through with it in the end as I didn’t have sufficient clearance with the crown.

I’m not sure if the new SuperMax fork travel can be adjusted in the same way as the PBR Lefty. These are great All-Mountain forcs as they have the lower bushing and are waterproof, don’t need bearing resets (not an issue really but an improvement) and are more like a conventional fork, and are far stiffer than conventional forks.

I meant that I didn’t increase the travel on my fork as I didn’t have sufficent clearance with the frame downtube, not the crown. The tyre would have clashed with the frame downtube before the fork bottomed out if I would have increased travel to 120mm. At 110mm the clearance would have been tiny, so I didn’t bother.

DanW: Yes, that’s what great about Leftys in comparison – the wearing surfaces are easily replaceable.

Wobbliscott: Of course, the needle bearings and shims are still there, so they will be fine. I’m pretty sure that lower seal is also a bushing though (that’s what makes it stiffer as it goes through the travel) – the lower leg is running through that so any wear would likely mean a new lower leg presumably.

DanW, yeah, I know what you mean. The manufacturers must allow a certain safety margin. Like the minimum insertion depth line on a seat post though, if you’re light enough, you can probably get away with a smaller safety margin.

wobbliscott, so you are talking about increasing the AtoC measurement then.
Although you say “If you cut 10mm off this spacer, then the fork will ‘bottom out’ 10 mm further up“
If you change that to “If you cut 10mm off this spacer, then the fork will ‘top out’ 10 mm further down” then it all makes sense.