Looking at getting a 4-banger
Am looking at getting a 4-banger for social XC, and endurance racing as I've just offloaded my Specialized Epic.
What are your thoughts on them? I love the Lawwill linkage and have a 98 Homegrown Straight 6 and 99 Straight 8 (and used to own an 00 straight 8)
Anyone have one available in a 17"?
Prefer a complete one, but would consider a frame only.
There is a 17 on Craigslist if you search nationally (San Juan Capistrano, CA). I LOVE my '99 Homegrown 4-Banger, and I loved my 2000 non-Homegrown 4-Banger. You'll find plenty of details here about them. If you already know the Lawwill from the S6 and S8, you'll be happy with the Banger. Plush as all hell, and very fun.
Know that there are multiple versions of the bike. The Homegrowns are their own animal, and the 2000 is its own animal, having a SID rear shock, lighter rear dropouts, etc. Don't expect a super-light bike and you'll be fine. Mine is just a tick under 30 lb with modern bits on it. Look for my posts about my bike, and you'll find info from guys like Bad Mechanic, Joemamad (who just got rid of his Banger stuff), shwinn8, etc.
For social XC, it's a great bike. I never plan on getting rid of mine. For endurance, it's a bit heavy, IMO.
Thanks for your thoughts CTB.
I've seen some posts with yours and others about and am very keen on one.
Would love the lighter one, but I would love a homegrown one with the bassboat paintwork even more!
My 08 Specialized Epic was about 13-14kg (26-28pounds??) so if I can build a 4-Banger to around that weight I'll be happy!
I'm a bit torn though. I'd love to run period spec parts on it, but for function and weight, and parts availability reasons I'm leaning towards modern parts.
I dont think it'd be all that hard to make a mount to run any type of air shock on the rear either. I am a fitter/machinist, and my brother is a toolmaker/CNC machinist/CNC programer so getting parts made is no problem.
I'm thinking a set of Rockshox Reba's and an XTR or Sram X0/X9 groupset with some carbon bars/cranks and a nice light wheelset.
High spec, period parts would probably be equivelent cost I reckon, but take much longer to source in good condition.
I'm looking at a blue/silver 4-banger this weekend hopefully, so once I have a frame I can start focusing on a build kit for endurance racing. Hello eBay!
Bellsy, any chance you need a 19? My 19 is a bit too large for me, and I haven't been able to find a blue/silver 17 to replace it. I'm hoping to find a 17" blue/silver frame, even if it is just a front triangle, and move all my parts over.
Doing the math on mine, 28 should be possible, but it'll cost a lot for a light wheelset and light crankset.
You may find it is harder than you think to design something that works for the shock. The eye-to-eye is very short at 5.5" average; simply making something that allows even a 6" shock with normal eyes to mount on there will raise the bottom bracket and steepen the head angle far too much, I've found. What the bike needs is a new upper swingarm design. I've been noodling alternate shock mounts for quite some time, and other than the one I had made for mine, I haven't come up with a better solution. If you do, definitely share!
PS: Period parts are cool for a resto bike, but IMO certain new parts work much better. My fork is a 2008, and the rear shock is a 2004. Off the cuff, I haven't found any modern brakes to be much lighter (if at all) than the simple Hayes brakes the bike came with, so I'm still running those. I'd like the adjustments of the new stuff, but the cost and weight have kept me where I am.
Yeah the one I'm looking at is a 17".
I've always run 17"-18" (Med) frames for my XC bikes. And all of my downhill bikes have been Med also except my first 00 Straight 8 which was a small. That thing was a weapon to ride on fast open courses. Although it was a small frame size, it was longer than most large sized bikes at the time, and had a lower stand-over height and low centre of gravity.
That bike took me to 2nd in C grade national series 2002, 2nd in B grade national series 2003 and multiple top 20 A grade finishes in 04 National series here in Aus.
Was so upset when it was stolen last year though.
So yeah, unfortunatelly for you I will be looking to keep the 17" frame size. Or a 16" Straight 6 if 1 pops up before hand.
The one I'm looking at has a very rough build of parts on it, so I'll probably replace everything bar the frame anyways, so using eBay, CRC, Wiggle, Aspirevelotech etc for parts, aswell as good 2nd hand items will keep the costs down.
As far as shock mounting goes... I'm quite confident that providing the body of the shock is roughly the same dia as the SID version, I can make any shock fit, regardless of eye-to-eye.
I'll machine up a trunion style mount, but instead of it clamping around the shock body as with the SID, I'll make the mount longer (like lowering the trunion mounting holes in the current clamping mount) so that the longer eye-to-eye shock can be clamped (or bolted via the bushing as per usual) higher up.
Sounds confusing I know, but I have the design in my head. And when I machine it up, I'll more than likely get a few done to sell to offset the costs a bit.
So, if you could run any air shock in your 4-Banger, what would it be?
Mounts could be made to accomodate 4/5/6" travel shocks no problems with this design.
(actually, I might post this up as a seperate thread)
I'm positive I've seen a couple 16" Straight 6's out there (the yellow 4-Banger based ones) in the last couple days, if that's something you'd want. I can check. EDIT: Ah, nuts. A nice 16" S6 frame just sold on Ebay with a Buy It Now. I knew I had seen one. You have better luck than I do - please find a second 17" frame and sell it to me. I've been looking for one for over a year now. I found one complete bike, but the insane owner wanted $2000 for it.
I've thought of your idea on the alternate trunnion design, but I haven't been able to convince myself that it will correctly restrain the shock in rebound, or that it won't lock up in compression. You end up having three pivot points in the design I'm picturing, and I don't think they'll all move in compatible ways through the shock stroke. I might try modeling that sometime, but I haven't convinced myself yet that it would work. Also, with the 4B frame, keeping a reasonable BB height means you really can't utilize more than a 1.75" shock without bottoming out. That's what I have on mine, and unless I run the head angle very steep and twitchy and the BB significantly higher than I have it now, it crashes (tire against upper arm and/or cable stay on the seat tube) as it is. I'm really not sure how the S6 got more travel, unless it was purely a product of the small 1.95 tires that they used back then and that the frames really did have different head angles than the 4B frames to compensate. (The tire moves into the carbon upper arm as you go into compression, and that hits on mine at full-jounce, but I'm running a huge Conti Race King 2.2.)
So if I could run any air shock on mine, it would be an RP23, but none of the lengths are compatible or can match what I have on my bike now. I'd either have to revert back to the original rear wheel travel (6.5 x 1.5 shock) or run into the geometry problems I mentioned above with one of the 2.0-stroke shocks. I definitely want to see what you come up with.
EDIT: I need to do some calcs with sag on the bike. Quite possibly, the sagged BB height with a longer-travel shock would end up the same as where I am now, even with the static ride height adjusted higher to accommodate. I'll have to math that out later, also looking at 120 v 100mm forks.
Last edited by CTB; 11-11-2009 at 06:49 AM.