Design The SOMA 29"er

somacisco said:

Hello 29inch gurus and fans:

I work for Soma Fabrications and we are finally getting around to producing a 29" wheel steel frame. Already settled on some specs: 631 Reynolds air hardening steel, 34.9mm OD downtube with headtube gusset, clearance for 2.35 tires, and 48/36/26 chainrings. We are not building your dream frame. The main goal is a quality steel 29er frame at under $399.99 that can be used for XC, trail riding and even touring and commuting.Something affordable for the (niche-seeking) masses.

Where we are locking horns with eachother is whether to:
1. Make it just a geared frame... vertical dropouts, disc mounts. If someone wants to do SS, they have to ENO hub it or Singleate it. But it is simpler, cleaner, least problematic but still versatile.

2. Make it ss & geared... horizontal dropout with a gear hanger... similar to the KM and Dambala. Highly versatile but possibly problematic.

3. Make it ss & geared by adding an EBB. This is cool, but would be the costliest solution. And also adds more weight. (Must give props to the GF Rig, very nice)

I've been checking out this forum for over a year now. Fun and informative to say the least.
Any input to help break up the stalemate would be much appreciated.

-stan

Click to expand...

Glad to hear you all are at it....more is better. We have to boot-strap this 29er economy, and it sounds like we're making progress.

I think to start off, you need to decide what your market strategy is:
*do it all, totally versatile bike (going after the Monkey)j
*low cost leader
*SS
*geared
*SS and geared
*etc

IE, what market are you going after...think of what you want the exagerated image of your frame will be....

Once you decide that, most of the options will take care of themselves.

My vote(s):
*a straight up competitor to the monkey would be nice, maybe lighten it up a bit, give us better standover clearance
*there is room in the market for a low-cost leader - geared/SS/both, focus everything on leading the cost war, and you may win on that...I used to work at Proctor & Gamble, specifically on the Crest brand. We introduced the SpinBrush, a battery operated toothbrush for 7 bucks, when the closest thing was around $40. Margins were razor thin (I don't know exact info), but it KILLED, and the rest is history...if you go low cost, you want to be the Model A of 29er frames....of course does that fit into your overall strategy?
*that modular dropout option is pretty cool, ala the Van Dessel Buzz Bomb...the Voodoo's sliding dropout doesn't look as solid to me, needs to be only 1 slot there...better yet, forget sliding dropout, just go Mutant dropouts, where you either bolt in a geared dropout, or a Track Dropout....

Probably didn't solve it for you...

Why the gusset?

Are you building a hucking bike? Even in an XL, I don't think you need to gusset a steel frame, unless you're really worried about the QC over in Taiwan and want some insurance (which, having been a Soma dealer at one point, I could understand - we saw all kinds of minor screwups on those frames - brake bridges not brazed on completely, dropouts misaligned, etc, etc. Eventually gave up on it because of that kind of thing).

I'd steer clear of the "do everything" model - the KM has that territory pretty much covered, and it sounds like you're not going to be coming in much lighter/better/cheaper, so avoid the competition there, I'd say. People like Surly, they like the Surly image, and they like the proven geometry of the KM. Even if the Soma is a pound lighter (the "Groove" was running around 4.5 pounds in a 21", last I checked, so a little over 5 pounds is a reasonable goal, unless you go the EBB route) a lot of people will take the proven option, or choose based on image. (I like the KM, but it mystifies me that some people think they're being independent/cool/sticking it to the man because they ride a Surly - do they not understand it's just QBP?)

In any case, I digress. Forget the 26/36/46 chainring clearance idea - nobody runs those kinds of gears anymore, especially not on a 29er. Forget the gusset unless you don't trust your fabricators to do a decent job. Forget the do-everything bike. Do a basic XC bike with a disc mount, canti bosses, and vertical dropouts, and let the SS people and various others modify as needed. There are plenty of people that just want to ride a regular old geared XC rig, they just aren't as vocal as us SS people...

Good luck.

-Walt

Hey Stan, great to hear there's another manufacturer ripe enough to join the 29" movement. I'm with Ibis-SS, very mature of you to come over here and ask opinions rather than try to figure it all out by yourself.
48t rings, those are not REALLY necessary. Perhaps if you were to build a Hybrid bike out of it, and you're the type of guy that only wears out the 11t on his cassette, because of his ultra-slow flatland riding style. I hope that only occurs here in Holland, though. Making the maximum 44t, you win a little bit in the chainstaylength/tire clearance department.

Definately be disc-ready. Make the bike look disc-only by using the optional Cantimounts VooDoo uses, which simply bolt on there. I like the look of that, some DJ bikes have it too. Sell the cantimounts opional, if that helps to cut down the basic price.
The Eno is quickly gaining acceptance. One thing you could do if you're making the bike geared-specific, is to make some popular Eno setups work out nicely, with a chainstaylength that works well with various gears in eno-mode.
If you want to do well in the magazines, a KM-like geometry, minus 2" of seattube, is bound to get great reviews. Right now, 29" bikes are still competing with 26" bikes, so they have to be a like steep on the headtube (no slacker than 71,5º headtube unless for a really small size to avoid toe overlap). If people want a more relaxed steering bike, they can just add a 100mm travel fork.
There's room in the market for an aftermarket ridig fork for sure. The KM set the standard in rigid fork geometry for 29"ers, and is liked by everyone, but curses by everyone for it's harshnes, and by some for it's weight. If you can make an affordable, around 2 lbs , 468-470mm rigid fork that doesn't try to brake the rider's hands, many will get one aftermarket or along with their Soma frame.
No more than 68mm of BB drop, on the KM that's been okay for the vast mayority, but Fishers that passed the 70mm barriers, got bad reviews for it. Stay between 55-68mm accroding to your beliefs, and you're ok. Personally, I'd keep them pretty low, stability is one of the main traits of 29", why take that away?
Definately make sure there's a full pound between your own offering and the KM. It's doable, and the psychological diffference of a full pound could persuade many riders to give your offering a closer look.
If you need loooong chainstays to make the 2.35" tire fit, slacken out the seatttube angles on the larger sizes a bit to compensate. People coming into the 29" sport probably like short wheelbase figures because they think shorter is better, and 29" bikes don't need superlong chainstays anyway, as the higher placed axles help a lot for steep climbing.

Ddi you ever see the adjustable chainstay length frame posted on the SS forum? If looked to be a cheaper solution than an EBB, and really simple, too. Not sure if there's a patent on it. Some bolts in grooves allowed for chainstaylength adjustment under the BB. Very long shot, but it could be an option for a SS-ready bike that doesn't require the Eno.

Many tall riders around now, see if you can make the largest size a 21.5" or 22". Riders for that size won't have much standover problems anyway. Only being 20.8" is the main problem with my Fisher.

Hope any of this helps, good luck!!

J

Another opinion...or maybe just another vote of the same

Running a 48t chainring is OK but 44X11 on the big wheel is all anybody really needs-wanna go faster? Just ride the road bike, right? My chart doesn't go to 44X11 but a 44X14 will get you to almost 30mph at 120rpm and most XC riding is 15 (or less).

I have an ebb and it's great! The problem is hitting the price point. If you can do it, that would be super. If not, maybe a regular vertical drop would be easier. ENO/Singulator are OK options. EBB/Vertical drops/disk and canti mounts would be excellent for everybody. A lot of people like the horizontal drops but for me they are really not good.

You probably only have to make 2-3 sizes-18/20/22 or whatever.

5# in these bigger frames is probably light enough to satisfy and be heavy enough to last. On top of most of us, 1# in extra frame weight is not a big deal but psychologically it's hard to warm up to the idea of a 6 1/2 pound frame like the KM.

Hey thanks for asking around about what people want in a 29" bike. That is cool! Good luck!

Soma

You mentioned touring as one of the uses and if it's supposed to be versatile, then it should be a good tourer. My vote:

It HAS to be able to run gears. (I singlespeed all the time on singletrack and love it, but if I want to run on the road, I have to change my gear, and for touring SS is just dumb IMHO.)
Eno is THE solution for the SSers. IT is great for tweaking your geometry as well!

Must have canti mounts (remove the studs if you don't like em.) Canti's are still the most universal, dependable, most common and easy to fix/replace system around.

Make a nice (sus corrected) fork to go along (lighter than KM)

Make sure you have drillings for racks/etc.

Shorter TT is ok, especially if you want to run road bars/dirt drops. However, don't make it too (hybrid) short.

Make it able to handle 48T - learn from FISHER DUAL SPORT! If you want to tour/commute it is a must. Off road, you only need the middle/small ring. Just give us MORE clearance than the DS (ie: less bb drop)