# Trials Geometry



## Clockwork Bikes (Jun 17, 2006)

Does anybody have some links to where I can read up on 26" wheel trials geometry?

Thanks, Joel


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## HomeGrownSS (Jan 18, 2006)

https://www.trials-online.com/images/geometry.jpg


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## Clockwork Bikes (Jun 17, 2006)

I found that pic but was hoping for a little more detail, explanation, discussion.

Thanks, Joel


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## pvd (Jan 4, 2006)

I wouldn't reference a bike built by Seven for understanding trials. It's not their specialty. Honestly, I don't know what is.

Anyway....

The echo stuff is sick. I love looking at their stuff. Here's some info on one of their bikes: http://www.echobike.com/bike20.html

Danny McAskill is killing lately. I belive he's using 24" wheels. He rides the Inspired product. That's probably where I'd really start. I'd shop around for geo for his setup since it's about the most progressive $hit going.

http://www.dannymacaskill.co.uk/
http://www.inspiredbicycles.com/inspired_fourplay_pro_bike_p12.php


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## Linnaeus (May 17, 2009)

pvd said:


> ... Honestly, I don't know what is.


Making $ is what they are all about. Not so much about craftsmanship or unique details, they are as "production" as you can get while doing custom frames. Not that there's anything wrong with having $ as your bottom-line-determine-everything factor, but it's certainly a lot different from the Walts/Garro/Rody/Sachs line of people. I've never seen one that really caught my eye. It's like a Bikes Direct ti frame w/ some custom geo and externally butted tubes.


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## pvd (Jan 4, 2006)

I really wouldn't put Sachs on that list. Nothing about his bikes are special. 40 years of the same junk.


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## Linnaeus (May 17, 2009)

...and oh yea, MacAskill _is_ killing it. I was blown away when I first saw the video where he throws a flare off a tree. (!)


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## Linnaeus (May 17, 2009)

Yea Sachs are all traditional for sure -- but my point was more about a passion for building, not a 'get-rich' enterprise. I'd toss Sachs in with the passionate guys.


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## pvd (Jan 4, 2006)

I'd give you that.

And, yeah, the flair off the tree was utterly inspired. The guy is sick.


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## Clockwork Bikes (Jun 17, 2006)

*Seven Trials Bike*

Thanks for the links, PVD.

I snapped these spy shots in the Seven shop 8 or 10 years ago (pre-digital).

-Joel


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## DWF (Jan 12, 2004)

pvd said:


> I really wouldn't put Sachs on that list. Nothing about his bikes are special. 40 years of the same junk.


Peter, it's impossible to take you seriously as a builder or a craftsman when you say **** like this.


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## smudge (Jan 12, 2004)

Clockwork Bikes said:


> I found that pic but was hoping for a little more detail, explanation, discussion.
> 
> Thanks, Joel


Joel,

There are several schools of thought on this and the answer you get will probably vary highly depending on the era in which the "topic expert" rode or competed.

Are you thinking about "pure" trials as in competition trials or trials in the better known sense which now includes a great deal of street riding?

The best stock bike I ever rode was a Crescent Ilions. Going from memory, 74° HTA, 13.5" BB height with 2.3" tires, 380mm chainstay length ctr-ctr. STA was steep but irrelavent. I don't know the F-C length but back then I figured out that the ETT was 24" if the STA was normalized at 73°. I used a standard Cannondale Pepperoni fork, I don't know the specs off the top of my head but my guess is that it was about 400mm a-c and 38mm offset.

more modern stock bikes feel crazy to me. the BB is usually + 30-50mm, they still have 375-385mm stay lengths but the F-C is in the 715 range. I don't know what current HTA's are but they feel slightly slacker than my old Crescent, I'd guess at 72°. The bikes are wonderful for "pure" natural trials riding but they're weird to manual because the front end is crazy long.

If you need any more info, let me know. If I can't answer it directly, I can probably get you in touch with a builder who can.


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## scooter916 (Jan 2, 2006)

http://www.observedtrials.net/vb/index.php

http://www.sinisterbikes.com/wtf.php


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## BeatAFool (Jan 14, 2008)

If all you want is # look at Tartybikes.com. If you want info on the # look on observedtrials.net but you'll have to plow through alot of horseapples to get it.


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## smudge (Jan 12, 2004)

Overall, the users at observedtrials are very young, uninformed and lack objectivity. There are several people there that started riding in the early 90's (as I did) and have seen the evolution of the bikes. Tarty definitely has a depth of knowledge that most others don't.


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## dr.welby (Jan 6, 2004)

Last time I looked into 26" trials bikes, bottom brackets were at about +50 but the trend was moving back down. For front ends the trend was getting longer, probably due to the popularity of those gap-to-front-wheel moves.

Lately with the explosion of Danny MacAskill my guess is that the trend is going to revert back to more like DJ bikes. I'd have to agree with other posters that you won't find much beard-stroking over the numbers - it appears CNC wizardry is more important.


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## Francis Buxton (Apr 2, 2004)

One of these days, I am going to build a trials bike instead of merely looking at them on webcyclery.


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## Clockwork Bikes (Jun 17, 2006)

*Thanks*



smudge said:


> Joel,
> 
> There are several schools of thought on this and the answer you get will probably vary highly depending on the era in which the "topic expert" rode or competed.
> 
> ...


Thanks, Sean and others. This will not be a pure trials bike, it'll see plenty of downtown riding. I have an interesting idea for a trials drivetrain I'd like to try out and want to build a general trials/street frame around it. I'll post when I start building in a few months.

Thanks, Joel


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## smudge (Jan 12, 2004)

Clockwork Bikes said:


> Thanks, Sean and others. This will not be a pure trials bike, it'll see plenty of downtown riding. I have an interesting idea for a trials drivetrain I'd like to try out and want to build a general trials/street frame around it. I'll post when I start building in a few months.
> 
> Thanks, Joel


No sweat. FWIW, my favorite 26" streety trials frame had a BB with zero rise/drop, stays a tad under 16", F-C about 685ish and a 72° HTA.


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## BeatAFool (Jan 14, 2008)

> bottom brackets were at about +50 but the trend was moving back down


some as high as +80, its great if you're on the rear alot but makes anything on 2 wheels hell for a novice

I sold my 26" Zoo, to buy a Triumph, boohoo..... I've been working out the details on my frame here's some of the numbers.

ha 72
cs 385
wb1090
bb +20
ht 101
fork 408
off 45

it's pretty standard for a urban/natural trials rig these days, if you want more urban/street shorten the wb

Trials is dead anyway, so who cares


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## Smokebikes (Feb 2, 2008)

"*Trials is dead anyway, so who cares*"................... Our trials bike experience consisted of only one frame....with the idea of building a "yard bike".......we quickly found that a bike does not make up for a lack of skill.........we sucked on that bike. Don't know what ever happened to that frame or who ended up with it..........it's probably hanging in somebody's garage..........maybe someday some kid will discover it. :thumbsup:


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## Marinobike (Aug 23, 2009)

*frames gemetry and built procces.*



Clockwork Bikes said:


> Does anybody have some links to where I can read up on 26" wheel trials geometry?
> 
> Thanks, Joel


please look my jobs:
picasaweb.google.com/marinobike
picasaweb.google.com/marinobikes
www.marinobike.blogspot.com

look all albums, have much informations. 
Thanks

Marino


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## toyota200x (Sep 9, 2005)

I am glad to see this thread pop up. I have been riding trials for the past 5yrs and have reached the expert level. [The following info is about stock 26" competition frames] In 2003 the first seatless bikes started to show up from Europe. They had BB rise that was neutral or a little negative. In 2006 there was a lot of really high BB bikes that came onto the market. Mostly from Echo and it's various other brands. Koxx [the high end frames from france] was also part of this phase. These bikes died out for a few years because the high BB rode amazing on the back wheel as a result of the +50mm or more BB and 375cs but made the bike feel weird for 2 wheel moves. Some people loved them and some hated them. In 2007 bikes had lower BB for the most part and this is what people wanted. Over the past couple years the high BB competition frames have started to make a comeback. These bike have a wheelbase of 1080mm or longer. The main difference from the earlier years of high BB comp bikes is that the chainstays are around 380mm. Not much of a difference but people seem to be in love with these new frames.

For an all around trials frame I would recommend something with a 1060mm wheel base, 380mm CS, 72 HA, and around 15mm on BB rise[this is with a std 400mm 45 offset fork]. This type of geometry will allow manuals and streety moves but could still be ridden in a comp. An all around good bike.


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## Clockwork Bikes (Jun 17, 2006)

Thanks, Marino and Toyota200x. Here's what I've got so far, it has 0 BB drop. It'll really just be ridden on the street.

Thanks, Joel


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## 3wfab (Aug 1, 2010)

are you looking for quote unquote bmx street style riding ie tear ***** up, or are you wanting more technical feel a la rear wheel moves?

More flickable in a 380 rear (especially with zero bb drop and running 26) and stiffening up the head angle to 73 or a tad more. Seat angle for me (I never sit and ride but I do build with seats, pivotal style) is damn near vert but I typically am around 35 BB rise. Help stiffens the top tube which you seem to be in the 23 inch range?

7/8 CS in the 049 area and if running 2.1 or bigger, use 83mm BB.

I can't figure out why trials peeps are using 68 wide shells and trying to jamb a 2.5 tire on it! I guess thats why you see all these fancy machined yokes......

just some thoughts-


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## Clockwork Bikes (Jun 17, 2006)

3wtab, thanks for the info. I guess I want everything. I haven't ridden in 6 years but when I did friends and I would head to downtown Minneapolis and drop off ledges, get up stone walls, boulders, pedal kick gaps, etc. but also tear down stairs and derby. At the time I was riding a Specialized P bike.

I left the CS length at 390 but will be making it as short as possible. This will be more clear to me when I get things mocked up in the jig. I'll be using a 73mm BB shell and I do have a simple yoke plane. The chainstays will be 7/8" x .035 and 3/4" x .035" seatstays. I'll be sure to post pics when I start in a month or so.

Thanks, Joel


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## smudge (Jan 12, 2004)

3wfab said:


> are you looking for quote unquote bmx street style riding ie tear ***** up, or are you wanting more technical feel a la rear wheel moves?
> 
> More flickable in a 380 rear (especially with zero bb drop and running 26) and stiffening up the head angle to 73 or a tad more. Seat angle for me (I never sit and ride but I do build with seats, pivotal style) is damn near vert but I typically am around 35 BB rise. Help stiffens the top tube which you seem to be in the 23 inch range?
> 
> ...


Most of the cranks made for the trials market only work with 68/73mm shells. Obviously it offers more component flexibility as there are only a small handful of manufacturers that build cranks for 83mm shells and even fewer (or perhaps none) that build for 83mm shells and chainrings smaller than 20t. With the shift from BIU to UCI style riding over the past ten years, running smaller chainrings seems to have become the preference for most trials riders.


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