Proprietary Geometry? Dec 18, 2009

Dropout graphic by All-City

Funny how discussions and the internet overlap. I was just talking to Jeff from All-City about the Dropout‘s geometry. As I was finishing up my email to him, I hopped onto my RSS and caught today’s post on Tears for Gears; vintage catalogs? SURE!

Catalog scan by Tears for Gears

As I’m reading his post, I scrolled down to the Eddy Merckx catalog. I read through most of it and then I came to the specifications table. Eddy Merckx considered their head tube angles proprietary and kept them a “secret”. It’s kind of silly to think about, but recent events have proven that bicycle geometry, especially with regards to the fixed gear freestyle bikes, can be somewhat proprietary.

Bruiser Geo

The All-City Dropout has a 73.5° HTA, the Milwaukee Bruiser has a 74.5°, the Leader 729TRK is a 74° the Charge Scissor‘s geo is still a mystery, with their site stating “71.5°?”. For the most part, the chainstays, top tubes and other dimensions are roughly the same. Are the head tube angles of these bikes proprietary? Are they the signature encoding that makes the bike unique? The seat-tube-angles are generally around the same and can be adjusted based on saddle-rail clamp, so I don’t see them as being as important to fixed gear freestyle bicycle geometry.

It’s an interesting concept. Geometry is what makes a bike and for various riders, the HTA is one of the deciding factors. Sure, street bmx bikes are steep as hell and bmx cruisers are more slack, where do 700c bikes fall on this sliding scale? Their predecessors’ angles were all over the place. What exactly is a “true track geometry” anyway? Some track bikes have a 72° HTA and others have a 77°. Bikes were designed around the events. A match sprint bike would have a steeper STA and HTA and the bikes used in longer track events had more relaxed angles. That’s just in reference to track bikes. Road geometry is also another one of those quagmires.

It’s something that all the “top” riders are usually discussing. Now that fixed gear freestyle riders have input on frame design (See the Volume Thrasher as a reference), we’re all getting the chance to study the great bicycle-design books and manuals of the ages. When we were working on the Bruiser. I tried to research frame design as much as possible and I’m sure Nick from Charge picked Super Ted and Tom’s brains on their preference. GOrilla had Wonka thrash their Kilroy prototypes around and give them feedback. Leader bikes polls riders on Trick Track and just about any company making a frame has people riding prototypes with different geometries. I’m not advocating one company or another, just making an observation. All this stuff is so nerdy to me and I’m glad to have had a part in this whole movement. I can’t wait to see more bikes come out and see where these manufacturers take their geometry.

In the end, special details like curved tubes, gussets, cleaves, clamps, track-end and fork tapers will mark the individuality of each of the frames. Much like modern-day BMXs. Who would have thought, two years ago, that we would be engaging in such a discussion?

Not me, that’s for sure…

  • Todd

    The lawyers can make a fortune enforcing bicycle geometry …no one else can. Pointless.

    No one cares if your frame’s geometry has an iron clad patent, or if its distinguishing feature is a 0.0000000000001″ steeper top tube!

    It’s *build quality* that distinguishes a frame! The material used, the welds, and the people who do the work.

  • prolly

    Tell that to Lemond, Merckx, Colnago and Cinelli. All those companies made their names by marketing their frames as having unique geometries and yes, details. Lemond loved longer top tubes, so his frames had longer top tube. Colnago had straight blade forks, De Rosas had specialized chainstays, etc.

    Details and geometry makes the bike. Sure, materials and construction does as well, but geometry takes hold.

  • matthartless

    John I truly enjoy reading your posts like these. They make my day. I’m glad I can be a part of this movement as well

  • andy

    there are only so many design options for each type of bike it would be ridiculous if someone patented the geometry.

  • sean milnes

    its pointless if youre commuting. if youre riding these bikes like we do, its not. if my plug could barspin without so much toe overlap id love it. geometry is everything to me. my next frame will be based solely on its geo…

  • Simon

    I’m no pro here but are we assuming that all these bikes have the same fork rake and will all run the same wheel and tire size? Wouldn’t a more valuable comparison for determining how your bike will handle be the trail measurement, the combination of the headtube angle wheel diameter and fork rake – ie the small Bruiser here looks to indicate a trail of 61.1mm which is pretty much a good average set up, not too quick not too slow at the front end. vs. the drop out with a trail of 72.6mm right on the outer limits (based on a 29c tire). No info on the others.
    I suppose also avoiding toe overlap is an issue as much as possible, this would depend also on the crank length, the pedal to toeclip end length (i.e your shoe size) to see if your front and centre is long enough. ie the Bruiser is 593.8mm which is sort of longer than some peoples suggested average probably to help with clip and the potential of bar spins.
    Speaking of bar spins the clearance, is effected by more measurements like headtube length, crown height head set stack height, fork length, HT and DT intersection point, DT angle our friend rake again.

    We could look at alot of other things like chain stay length effecting wheel base, the BB drop and so on which all determine subtly how a frame set will ride but I am coming to a few points.

    A) No one angle on a bike is going to make one better than the next bike, it is the harmony of these lengths of metal and angles of pipe that make one bike ride better to one person.
    B) How do these specs measure up to your specs? if we tick the boxes of bar spins, solid handling, and what ever else you want out of a street track bike which we assume to be taken care of on most these frames (don’t know all the fork specs on them to get trail etc) then which one is actually going to work best under your monkey arms or little girl legs? Your slightly longer or shorter or like the bike longer and shorter in areas you might carry weight up top or be all legs so need to compensate on these things by looking at the fine details in the lengths and angles (you cant always compensate with long or short stems long seat posts and slid forward saddles).

    Try them all out if possible or think how your current ride is set up comparatively and where you want this frame to take your riding and decide from there on your short list then think about which ones are actually made well- John your on the money, it is all in the details.

    Sorry about the essay!

  • Ronsta

    John, great post.

    Bottom line, you can’t patent frame geometry. You can brand it like Gary Fisher and a number of others, but you can’t sue someone for doing a similar design. Go back through history far enough and you’ll find its all been done before at some point.

    Still that doesn’t mean you can’t have fun exploring it. The double-diamond bicycle frame frame still offers a seemingly elusive array of options for finding that “perfect ride”. People are quick to point out a single angle or length, but these affect other aspects of the bike. A HT angle is fine but what is the fork rake, and the trail your looking for? A skilled builder/designer knows how these numbers all affect each other and how to use them. It’s looking at the combination as a whole.

    I know of some small ‘made to measure’ builders who prefer to keep their geometry confidential. But if it’s custom, who cares, it’s only designed for one person. As for design, as any form of riding evolves, bike geometry changes with it, so enjoy the journey!

    Dig this discussion man, keep it up!

  • burrito_pack

    74.5, it’s the shit, been riding for a long time and frames that go 75 or 74 just don’t feel like home. the bruiser will be mine if rent and work will figure it out.