Kirk Pacenti Offers Open Source Freehub Design, Suggests Industry Moves Forward

I’d do it in an instant!

This would be good for crankarms as well. These guys are already doing it: http://groovycycleworks.com/HotRodCranks.aspx

That looks very like the proprietary polygon interface (Based on DIN 32711 P3) that e*thirteen use on their cranks.

@Jeff – My thoughts exactly.

Excellent idea. Would also make it easier to get the 9t cassette cog movement off of the ground for those of us that want to use a single ring and ultra-wide range cassette – such functionality could be designed right in.

I’ll start working on a cassette extractor tool! they can be different spline tools for each manufacturer.
this is stupid

http://en.wikipedia.org/wiki/Reuleaux_triangle

How would you broach cogs for this?

I am glad to have someone with a voice for logical change like Kirk Pacenti. There are many of us that wish for improved standards for various parts in the bicycle industry, but unfortunately we don’t have a recognized name like Kirk does – so our ideas go unnoticed. By making it open-source, it would hopefully prevent all the arguments & litigation over patents & proprietary designs. Obviously, I’m for it!

Thanks for the support. I think the idea has merit and some large companies are looking at it as we speak.

The goal is to create a new standard for the 2014/2015 model year. Hopefully it would allow for a single 10/11 speed standard with room for more cogs down the road. (you know it will happen) I also want to be able to accommodate 9t cogs if possible.

As for the shape, there is nothing proprietary about it. It has been in use since the 40’s in many different industries. This shape would likely make manufacture of free hub bodies and cogs less expensive because of the reduced complexity.

Pacenti has been “tinkering with this concept for about four years and thinks it could realistically move into production by 2014/15.” Really? Is anyone as unimpressed by that as I am?

Yes, you could replace splines with something else that you stole off a crank-maker’s website, but what are the reasons you should? Just what would this design offer that we don’t already have? It needs to be valuable enough to convert to an incompatible standard.

It would seem like 4 years of tinkering should yield more than an idea that we could do something else, but Pacenti is more demagogue than engineer.

Not sure how removal of the cassette would be much easier. The Groovy cranks use a pinch bolt design, while the e13 cranks have a self-extracting crank bolt to remove the non-drive side crank arm. Would this design require a press fit, or would the machining tolerances have to be super precise? I’m just not entirely sure how this design functions compared to other Reuleaux triangle designs. Maybe we could get a follow-up explanation from Pacenti?

Steve, if you’re having that much trouble installing a cassette onto a freehub body, you may want to drop cycling in favor of golf. golf is a sport you can do while smoking a cigar. and now the golf purists will howl. purists love to howl.

@secondtimeuser
you know if you just did sram with 11-36 cassette and a 53 tooth up front you can actually get a wider ratio than a standard 53-39 x 11-25. Also a 9 tooth cassette cog would put massive friction on the chain.
If you really want to be a weight weenie you might as well just look at specialty/custom ultra low weight parts or a lighter something else instead.

@fleche1454
The goal of a 9T cassette isn’t to use it with a 53-39 road crank as a weight weenie part. Interest in 9T cassettes is with mountain riders who want to switch to single chainring and get even wider range than 11-36. 400% is a lot more flexible than 327%. I agree with secondtimeuser, supporting 9T and 10T cogs would be a win, roadies don’t need to use small cogs if they don’t want to.

Just a quick note on the hive / e*thirteen polygon design: our BB interface is based on the DIN polygon standard, which is described in the machinery’s handbook, among other places. We don’t claim to have invented it. Our interface is proprietary because we started with the standard polygon shape and changed it to suit our application. We don’t claim to own anything to do with polygon couplings other than our own implementation of the concept.

Using a polygon for the freehub body interface is an interesting idea – we’re looking forward to seeing what develops!

I need to see tangible benefits before making such a change. Otherwise, I would do something like this simply to show it off at the trailhead.

It’s the same reason people ride Jones Bikes–no benefit whatsoever other than having a reason to strike up conversation at the trailhead. People with few friends usually get such bikes.

Terra Forma Evolution hubs also have some inovative hub ideas. They use the space under sram powerdome cassette to place the bearings wider and use a much larger engagement system than a regular hub. I’ve never tried them but they look like an interesting cocept. Very spendy though.

So Terra Firma evolution really just evolved the old shimano screw on freewheel using a sram cassette sticking more teeth in there and some cartridge bearings

How about an innovative company engineers a product that takes the design of the whole bicycle into account and not just the bits company A B or C decided to bolt to it which now BTW contain so many compromises that they are just about survivable

I hope the design of freehubs follows bottom brackets where the first the real evolution was putting a bigger axle and bearing in it it just goes to prove bicycle design is a joke and lead by marketing hype .

The only downside is that pacenti seems to genuinely want to make a better bike maybe pull out your pens and pencils and just do the whole thing would be a step change the industry needs not incremental dilutuion of every standard going

Grove used the tri-lobe design for crank spindle in 1978 for their HOT Rod cranks, the first modern two crank piece design (pre dating bullseye). Groovy had recently licensed and re-vamped the design for the new Hot rod cranks, using the same spindle interface using a pinch bolt. E13 borrowed the idea from Groove & Groovy used a modified “press-fit” version of the same idea. While Grove was the first to use it in a crank spindle application, and E13 obviously borrowed and slightly changed the fastening design, neither claimed to have invented it. Both were based on an existing DIN torque shaft interface standard used in motor/drive applications. It is an excellent torque transmitting shape with much greater surface drive contact than splines or straight sided polygons. The design is just as sound for “slip-fit” applications like cassettes. Cassettes now use slip fit splines, analogous to presfit crank splines like Isis, or Octalink. A slip fit tri lobe design, held in place with the same lockring we use now would be just as sound.

My only question woudl be how to handle the “timing” of the individual cogs. Current designs use a single larger spline to ensure all the cogs are aligned properly. would you use a notch, or single spline to “line-up” the cogs?

If it works elsewhere on a bike, why not re-apply it to another bike part? Current design has a problem. It was fine when both cogs and carriers were all steel, the notching wear was minimal. Now with so may aluminum, or titanium carriers, combined with cogs made from similar softer/lighter materials, the notching and wear of the splines is a problem that could use some addressing. This would open up more material possibilities for carriers and cogs too.
Obviously, a single piece cog/carrier (like current single speed BMX drivers) could be stronger/lighter but would be much more expensive (SRAM XO and RED casettes for example). If it does go forward, i’m sure the market will chime in with a few “better” new standards, which will just make for consumer’s, and mechanic’s frustration and marketing hype that will muddy the water, clouding the original good idea.
Doing it as an open standard is a good way to help prevent this.