[samnation]

Hey guys,

I am having a custom frame built based around 29"wheels. The frame is going to be a long travel trail hardtail think like 140mm fork slack head angle short stays and low standover. Little backstory about me I am 6'1" and come from riding trail/freeride/downhill bikes with headangles anywhere from 65 to 67.5 i also have spent a bunch of time riding the west coast (specifically the north shore/sunshine coast) and whistler. The inspiration to do this bike is Chromag essentially I want a Chromag on 29" wheels but am way to desperate to wait for them to release it. So i need some help...

First with headangle on a 26" wheel I would want a 67-67.5 headangle what does that transfer to in a 29? bearing in mind they have to have a steeper angle.

Second with chainstays I want them short but at the same time have clearance for 2.25 mud tires. Looking at other bikes most seem to be between 435 and 450 with the specialized stumpy in at the shortest and the low end specialized in at the longest, However i have only studied carbon and aluminum frames so naturally the lengths will be slightly different...

Thanks for helping a new guy out.

 

[MMcG]

Who's going to do the building?

Some good reference point frames to look into are some of the short Chainstay 29ers that Steve Stickel has built - google ByStickel

Some production frames to use for comparison/inspiration include the last batch of Sinister Simon Bar frames, the Canfield Yelli Screamy, and the Banshee Paradox.

Another frame to look into is the Siren Bikes - John Henry model.

Also look at some of the frames built by the guy behind Wolfhound Cycles

good luck!

Mark

 

[samnation]

Thanks for the info its helped for sure.

Made me wonder though how banshee got the Paradox down to 426 when others averaged out to 440 or so..

The frame is going to be built by Marino bike. A friend had a bike built by him, the price is unbeatable for a custom frame and from his experience the frame is going well. The only issue is that Marino doesn't build 29ers often so i need to have my measurements and angles down pat.

So far
Head angle: 68*
Seat angle: ?
Chainstay: 17.3 (440mm) (was fully "committed" but the Paradox and yelli screamy chainged my mind thinking i could go shorter)
TT length: 23.5-24 (596.9mm-609.6mm)
Seat tube length: 18" (457.2mm)
Standover: 30" (762mm)
BB height:?
Headtube length: 4.3" (110mm)
BB size: 68mm
Tire size: 2.25

My seat angle and bb height will be fully set when i lock down the others. I am going to work on fitting on some 18 and 19" bikes to see exactly where my seat tube will fall. my top tube is undecided because i want to run a 50mm-60mm stem so it needs to be as long as possible another thing i will have to play some games with to see what top tube works at the risk of making it too long.

The big thing for me has become chainstays I need to figure out if i can go down to say a 430mm and still have no tire clearance issues and NOT have to have a bent seat tube, Luckily when the frame is built I will give a tire clearance i expect so i will know during the production process.

If anyone sees anything that immediately sets them off as being weirdly off let me know I am new to this and it is my first 9er.

 

[MMcG]

You might want to look at the Geometry of the Kona Unit frame as well. That might give you a good idea of what your builder could do for you. The Unit has slacker angles this year (2011) and it also can go to about 17.1" with the sliders all the way forward in back.

Good luck on your 29er custom build adventure.

 

[shiggy]

Thanks for the info its helped for sure.

Made me wonder though how banshee got the Paradox down to 426 when others averaged out to 440 or so..

The frame is going to be built by Marino bike. A friend had a bike built by him, the price is unbeatable for a custom frame and from his experience the frame is going well. The only issue is that Marino doesn't build 29ers often so i need to have my measurements and angles down pat.

So far
Head angle: 68*
Seat angle: ?
Chainstay: 17.3 (440mm) (was fully "committed" but the Paradox and yelli screamy chainged my mind thinking i could go shorter)
TT length: 23.5-24 (596.9mm-609.6mm)
Seat tube length: 18" (457.2mm)
Standover: 30" (762mm)
BB height:?
Headtube length: 4.3" (110mm)
BB size: 68mm
Tire size: 2.25

My seat angle and bb height will be fully set when i lock down the others. I am going to work on fitting on some 18 and 19" bikes to see exactly where my seat tube will fall. my top tube is undecided because i want to run a 50mm-60mm stem so it needs to be as long as possible another thing i will have to play some games with to see what top tube works at the risk of making it too long.

The big thing for me has become chainstays I need to figure out if i can go down to say a 430mm and still have no tire clearance issues and NOT have to have a bent seat tube, Luckily when the frame is built I will give a tire clearance i expect so i will know during the production process.

If anyone sees anything that immediately sets them off as being weirdly off let me know I am new to this and it is my first 9er.

A bit late to the thread--

Short stays have many clearance issues: tire to stays; tire to FD; tire to seat tube; tire to chain (low gear chainline); chainrings to stay; crankarm to stay...

The 68mm BB shell will make make things tighter.
STA affects tire to seat tube clearance, as does BB height (steeper/higher = more clearance). Note how close it is on the Paradox even with the bent ST and the Y-S uses an offset ST.

Your builder is going to need to be very creative you give you any sort of tire clearance with stays shorter than ~440mm.

And I would want more than just a few millimeters of space for a NS bike.

The fork you intend to use needs to be figured into during the design stage. Travel, A-C, and offset are important.

Need to know how you want the bike to fit. It determines the STA and the position of the bars. Even the best stem length can be more a factor of the HTA than the TT length. The final TT length ends up being what it needs to be as a result of the rest of the elements of the frame geometry.
Specing a HT length is fine but it is not the only factor for bar height. The fork A-C length and BB height (BB drop in frame terms) come into play. Given the same HT length, a longer fork raises the bar. A higher BB (less drop) lowers the bar.
Have to know what you want. The fork length, HT length and BB drop also affect standover, and what needs to be done to get it as low as wanted.
Just picking dimensions that sound right does not make a good bike.
Setting the fit/function points and then connecting the dots--even if the geometry chart numbers look odd--creates the best bike.

 

[alpine slug]

The current On-One Inbred 29" has everything you say you need but with a slightly steeper HA.

If you haven't ridden 29" bikes very much, you may be overestimating the need to slacken the HA. A lot of people assume they need slacker HA than what will give them the ride they want.

I would try to find an Inbred with 100mm travel fork on it, and ride that. That's what I ride and I can't remember a time when I thought the HA was too steep. I understand that it's 70deg with a 100mm travel fork.