Ibis Ripley 29er

by Brian Mullin on August 31, 2011

Overview

We are excited and proud to announce the Ibis Ripley 29.

Features of the Ripley 29:

  • 29″ wheels
  • 120mm rear wheel dw-link travel
  • Twin angular contact composite bearing eccentric linkages
  • Full carbon fiber monocoque with sacrifical core molding
  • Tapered head tube (Cane Creek AngleSet & Chris King InSet compatible)
  • Kashima coated Fox Float RP23 with Adaptive Logic Boost Valve technology
  • Clean cable routing with molded carbon cable stops and provisions for cable-actuated adjustable seat posts
  • BB92/Press GXP style integrated BB is lighter and stiffer and better for molding
  • 142mm Maxle rear axle provides high axle stiffness with QR ease of wheel removal and installation
  • 160mm carbon fiber post mount rear brake mounts
  • High direct front derailleur, mounted to swingarm
  • Geometry designed to work with 120-140mm forks
  • 34mm fork stanchion approved
  • 4 Sizes (S, M, L, XL)
  • Weight TBD
  • Price TBD but in line with our other frames
  • Delivery TBD, but not in 2011

 

The Story of the Ripley

The Ripley 29 project started in 2008. The Mojo and Mojo SL were already in production and well received, we were ripping around on our Tranny prototypes, and the Mojo HD was designed and getting readied for production. In other words, it was finally time for us to get our first 29er project moving in earnest.

We approached Dave Weagle (suspension guru, inventor of the dw-link who has never let us down on a suspension design) and told him we needed a bike that had the versatility of the Mojo SL. It needed to be efficient for racing but not so focused on it that that’s all it was good for. We asked for 100mm of travel and told him we wanted to be able to build the bike to be the lightest and stiffest in class. What he came back with surprised us: He had figured out how to shrink the whole DW link system down to two tiny and durable eccentric links (more on that later).

During the same time we were riding other 29ers and realized how we were spoiled by the 140mm of front and rear travel found on the Mojo. The big wheels certainly mitigate the shorter travel, but 100mm forks to us felt like we were going back in time (not in a good way). We’re were sure a 100mm bike would make a World Cup fire road racer happy but it wouldn’t really make us happy. Back to Dave. Can you make the eccentric bike have 120mm of travel and still be just as efficient? No problem he said, so we got to work.

Designing around 29″ wheels presented a new set of engineering challenges. How do you make the geometry feel snappy, but maintain toe clearance in the front and an ample tire clearance in the back? How do you keep the front derailleur from hitting the rear wheel? Where do you fit the suspension linkages and shock (while maintaining a short wheelbase, low weight and high frame stiffness)? Can you design the frame to be light and stiff, but still accommodate water bottles? What is the optimal amount of travel for a 29″ bike that will be as versatile as the Mojo SL? How do you accommodate the different gearing needs of a 29er whether using a 1X, 2X or 3X drivetrain? Where do you put the head tube with a fork that tall and keep the bars in the same place?

These were some of the questions we asked ourselves as we started the design process. Now, three plus years later, here’s how we tackled those issues.

Prototype
To prove to ourselves that the short coupled eccentric links would actually work as well as we thought, we built a single prototype, using a Tranny as the starting point. It’s definitely not be the prettiest bike we’ve built, but it proved a point. The eccentrics worked, extremely well it turns out. This gave us the confidence to move forward full speed ahead on the Ripley 29 project. To read more about ‘The Mule’, our prototype project, click here or on the picture below.


Eccentric Links
The all new linkage technology warranted it’s own page, so you can read about it in detail in the ‘Tech’ tab.

Molding Technology
The Ripley 29 uses similar molding technology to the Mojo SL-R. We start by molding a sacrificial mandrel in exactly the shape that we want the inside of the frame to be. That becomes the 3D template for the bladder that holds all the carbon preform before it’s laid into the mold. This allows the lay-up to be done in one piece, with no joints anywhere. The result is a more precise lay-up that eliminates the need for additional foam or filler to mold the complex shapes. What that means for you is a lighter and stronger frame, critical factors in hitting our targets for weight and stiffness.

Headset
We like the tapered headset found on the Mojo HD and Mojo SL-R, so we’re using it on the Ripley 29 as well. It’s light and very stiff. The 1.5″ lower provides an exceptionally rigid front-end platform. Combined with the through-axle fork and our very stiff front-end layup, you’ll be amazed at the precision steering feedback you get, particularly when pushing hard.

You may use several different Cane Creek headsets or the Chris King InSet headset.

Two Bottles
We’ve made a provision on the Ripley 29 for 2 water bottles, one above and one below the down tube.

Cable Routing
Cable routing is provided for cable actuated adjustable seatposts. An optional polycarbonate cable guard is available that bolts under the down tube, under the second water bottle.

High Direct Front Derailleur
The swingarm mounted front derailleur is always in the right place in relation to the chain and chainrings so front shifting is more consistent throughout the travel.

This mounting system provides increased compatibility with 2 x 10 drivetrains and less chain slap since the chainstay can be located further from the chain. Also since the derailleur is moving with the chain there will be no chain rub at the extreme ends of the travel.

Single Rings and Chain Guides
If you want to run a 1X10, we’ve got great news. In June 2011, Shimano began shipping a new rear derailleur call the XTR Shadow Plus. It uses heavier chain tension plus a friction stabilizer to dampen the cage and thus chain movement (chain slap). It also dramatically reduces derailing of chains. Combined with either an e*thirteen XCX-ST D-Type or an MRP 1X, the Shadow Plus virtually eliminates the need for the lower half of your chain guide, plus makes your bike nearly silent.

142 x 12mm Maxle
The 142mm Maxle rear through axle provides gobs of extra rear wheel stiffness in an extremely lightweight package.

Bottom Bracket
The bottom bracket is the new press fit integrated style called the BB92, also known as PressGXP. Once again, it provides you with a lighter, stiffer bike, and is compatible with most popular cranksets.

And Finally, Why Ripley?
Contrary to what some might be thinking, the name didn’t evolve from “Ibis has a 29er, believe it or not!”.

The real reason is that at Ibis, we think recycling is a good thing to do. But why limit it to cans and bottles? You may have noticed that we’ve recycled a couple of names recently. The Mojo, now a carbon fiber dual suspension bike, was originally a steel hardtail. The Hakkalügi was our original steel cross bike. The Silk Ti was a softtail and now the Silk SL is our road bike. The Tranny? Well, that was just a questionable encounter at one of the Vegas trade shows.

The Ripley was an aluminum softtail, very innovative and lightweight. You can see it in an archived web page here.

And for giggles, here’s a picture of the original Ripley, a couple hundred yards from Chuck’s house. Yes, that’s Robert Ripley’s actual grave, believe it or not.

Tech

“We’ve been working on this bike for what seems like forever. Far before it was fashionable or even heard of to have a shock clevis, and one of the first bikes since the I-Drive and Decathlon to use any type of eccentric link. Obviously more is better so we have two of them!” Dave Weagle

All new dw-link from the eccentric mind of Dave Weagle
As we mentioned on the details page, when confronted with the design challenge of building a dw-link that was able to withstand the larger forces of the bigger wheel AND be as light or lighter than the current dw-link bikes, Dave Weagle came up with yet another innovative idea: eccentrics. Plural. As in 2Xentrics. The dw-link suspension on the Ripley 29 consists of two short-coupled links in the form of two rotating eccentrics, an idea he’s been batting around in his brain since 2005. He knew immediately that this was the right application for this new design. Read on for an explanation of the eccentric technology. To get a visual explanation of the eccentrics, head on over to the ‘Photos + Videos’ tab above – we’ll soon have a short video we’ve created showing the eccentrics in motion. Check out the picture below with the two eccentrics sitting next to what they replace on a Mojo SL or SL-R. They’re also 130g lighter.

Eccentrics: two short-coupled links in the form of two rotating eccentrics. 130 grams lighter.

The eccentric world of eccentrics:
When Dave suggested using eccentrics it sounded like a good idea. Eccentrics as an engineering solution are slick and elegant. We’ve always liked the quote attributed to Einstein that says: “Everything should be made as simple as possible, but no simpler”. As it turns out it’s pretty hard to keep this simple idea simple. The picture of the eccentrics above represent the 20th iteration of the design, and each time the design got simpler. We like where it is now.

The thing about dw-link is that it’s based on physics and math. Dave can’t just put the links where ever he wants and slap his name on it. They have to go where the equations that he’s derived tell him to put them. Unfortunately this means that as he shrunk the links they had to get closer together. In order for things to get small enough to use eccentrics the links got so close that we ran out of room for ball bearings. In order to make the eccentrics work we started looking at bushings because of how thin they are. Also, bushings are actually better than bearings at oscillating motion so when designed right they’ll last longer. We set some pretty high standards though: no play, friction comparable to ball bearings, no special tools, lighter than our current link and bearing system, and perhaps most important, field adjustable with standard tools.

As mentioned, as we were beginning the Ripley 29 development, we were finishing up the Mojo HD. During that project we figured out that the first couple of mm of deflection during a stiffness test is actually from play in the ball bearings. The way we solved it on the HD was to use dual row angular contact bearings on the main pivot. There was no way those were going to fit between the eccentrics or be light enough. So we had the idea of angular contact bushings? And then we thought what if we made them adjustable so that as they eventually wore you could take the lash back out? We got in contact with the guys at Norglide and they started showing us some very slippery and durable composite bearing materials. We did some proof of concept experiments and were impressed so we started working out our eccentric design.

It took a while but what we came up with was a sealed, fully adjustable, angular contact composite bearing eccentric linkage system that is field adjustable. As mentioned, the eccentric system weighs 130 grams less than the Mojo linkage system.

We did some durability calculations and we predict that the eccentrics will outlast the bearings in our linkages considerably. We designed them with extra load capacity which provides increased life. The system is sheltered from direct spray by the design of the frame and also fully sealed. When you do go to replace the bearing material it is easier than pressing bearings out and less wasteful and expensive than replacing the entire link. It’s just the cone shaped bushing material that needs to be replaced. Not that you’ll need them in your lifetime, but they will be reasonably priced.

What’s a Norglide?
Norglide is the trade name of the composite bearing material we use. It’s made of a new material (It’s only been around since 1938) called Poly Tetra Fluoro Ethylene. Fluoropolymers have been used as bearing materials for over 50 years and continuously improved.

Norglide has a bunch of features we are looking for. It’s maintenance free, strong (has a metal support structure) is durable due to its wear-resistant PTFE compound and it can also have high load capabilities. So far so good. The coefficient of friction of a composite material is not a constant. It is dictated by the material of the mating contact surfaces and by the roughness of the harder one. With combinations that have very different strength values (like ours does, aluminum and polymer) the coefficient of friction also depends on the load, speed and ambient temperature. What we found out from all of this is super good news: the coefficient of friction drops as load increases and as speed decreases. That’s the exact mix of properties we were looking for in this bearing.

An exploded view of the eccentric, part numbers 4 and 10 are the bearings.

Super Duper Long Lasting
Our engineering staff (his name is Colin) did a whole bunch of calculations on the longevity of the bearing. The number that the equation spit out was that you can ride the bike for two hours a day for years before you need to replace the bearing. Colin checked the calcs with the manufacturer’s engineers and they gave his math a thumbs up.

If you haven’t done so already, we recommend you check back soon for a look at the little video we’ve prepared that shows the various features of the bike, including the eccentrics in action. Click on the ‘Photos + Videos’ tab above to get edumacated.

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