Wednesday, December 07, 2011

Short Stays Syndrome

Image courtesy of Singular Cycles
Ever since 29"ers hit the scene, it seems that everyone wants them to handle like 26"ers.
This is most evident in the latest movement to get the shortest chain stays possible on 29" wheeled bicycles.

Short chain stays make bikes more______. (Fill in the blank, there are a lot of things folks will put in here.) The funny thing to me about all of this is that most folks are calling these short chain stayed bikes"All Mountain Hard Tails", which is a bit of an oxymoron, really.

This new popularity for these rigs is fascinating. On one hand, you have folks clamoring for slack head angles and long forks while at the other end you have the short chain stays and rigid, efficiency of an XC racing rig. This isn't really anything new though. This was tried with 26"ers long ago.

Those bikes had geometry which was abandoned for the most part. Too sketchy on the down hills and too easily looped out on steep climbs. In many ways, I see the 29 inch versions of these bikes as being even worse than the 26 inch versions.

Yes- I have tried the sauce. I had it all from the 120mm fork to the shorter chain stays. I did not have the slacker head angle, but it wouldn't have made any difference. The problems with the 26 inch versions of this idea did crop up with the bike I set up too. But......I ended up really liking it in its final version. What was that? Well, it was a short, rigid forked version that transformed the bike into a single track ripper.

Short and Quick
The bike was the Origin 8 Scout. A heavy frame, probably about as heavy as many as these steel "All Mountain Hard Tails" are, but without the slack head angle, as I stated before. I wasn't thinking I'd ever get the bike to be fun, that is until I set it up as shown here. Then it all clicked. Lower front end, more balanced weight distribution, (ie: not all on the rear of the bike), and the shorter wheel base made getting it to giddy-up around tighter corners a breeze. I still have this frame, but I simply detest the rear drop out/brake set up. Really nasty design there.

Then I see things like the prototype Singular above which gets me thinking about how a low slung, shorter wheel base, shorter rear ended bike would make for a killer single track bike. You can keep the long forks and really slack front end. Not necessary. Really- just get a full suspension bike and be done with it. 

To my mind, this whole shorter stay thing belongs in XC/Trail hard tails with fast geometry and short wheel bases. Not in a category dominated by full suspension bikes. You know, that domination of full suspension in the AM category happens for a reason.  A really good reason!


MG said...

I agree for the most part... I love my Salsa BWNN with its 17.5" chainstays, which are about .4" shorter than a stock Ti Fargo. It's a difference you can feel immediately out on the trail and it's something I dig. Personally, for "bigger" bikes, I'm less set on the virtue of super short stays, though my good buddies in Colorado at REEB Cycles are making a compelling case for it with their gnar-terrain Gates-drive SS steel frame. If you haven't ridden one, it's an eye-opener... Definitely not a Midwestern 29er by a long shot, but in its element (gnarly, rocky, technical, mountainous singletrack), a wicked-fine handling steed. So, if kept in perspective, with overall balance in mind, I think it's possible to do an "all mountain" hard tail with short stays that rides and handles well. At least I have ridden an example of the breed that I'd deem "worthy"...

Miles said...

I have a short chainstay 29er I made myself that I really love, it's got 430mm chainstays, 72* st angle and 71* headtube angle and a rigid 50mm offset fork, oh and 70mm of bb drop. It absolutely RULES on our tight northern california single track, not sure how it'd do elsewhere, but I love it here.

That said, I don't know that I would be so quick to write off 29ers with relatively short chainstays long travel forks and slack ish head tube angles. I want to make one and try it out. It seems like the slack head tube angle would lengthen up the front center and make the bike really stable and comfortable feeling in really loose steep terrain while the short chainstays would make drops and manuals and things that having a relatively short wheelbase are rather nice for. I usually try to stay away from slack headtubes, but it seems like they go along with forks of at least 120mm of travel.

Guitar Ted said...

@MG: I think a bike with shorter chain stays, longer fork, and slacker front end could work if carefully tested and thought out, but to my mind, a lot of these bikes are going to have to make some serious compromises in drive train compatibility, climbing ability, and possibly in tire clearances.

One thing I would really want to se on a bike of this nature is a travel adjust fork to aid in keeping the front end in check during climbs. Otherwise it starts to look like a down hill only machine, and to my mind, that is not "All Mountain".

@Miles: Historically, as I pointed out, having really short chain stays was shown to be not optimal. While popping the front end up easier makes it sound like the bike may be more fun, it doesn't bode well for other necessities of what I consider "all mountain" biking to be. (See comment above)

Whether or not I am "writing them off" doesn't matter. They are here, more are coming, and riders will be making up their own minds soon enough. My concerns still remain.

I hope to get aboard one of the better examples during 2012 and report on whether I am unnecessarily concerned or not. ;-)

redstone said...

Not all bikes are built for all terrains and circumstance. As owner of mentioned REEB (5" fork, 69deg HA, 17.5 stays, belt drive, SS), I can testify that it is a completely suboptimal setup for the flats and rollers of the midwest. Been there, done that, didn't like. But...

In steep and technical rocky terrain of CO, this bike is absolutely superb. I've got a short and tall stem to boot. It climbs well (SS in CO means you're standing) and descends even better. For the terrain I ride, this is the best handling hardtail I've been on.

Next time you want to check out an AM hardtail 29er with that geometry, check it out in an environment for which it was designed. You might be surprised.

Guitar Ted said...

@redstone; Thanks for your comment. I get that you are passionate about the bike, but to be fair, 17.5 inch chain stays are not considered "short" these days, and not what I was referring to.

I think you are probably well aware that the Origin 8 Scout actually has a shorter effective chain stay.

Also, I think you are well versed enough to understand that compromises in crank set choices, front derailleur operation, and tire clearances are very real at what is considered "short" for 29 inch chain stays these days. (Typically anything 17" and less).

These are the sorts of bikes I refer to. And I have ridden in the Rockies and do understand the terrain is different. Thus my concerns.

As I stated in a comment above, I hope to catch a ride or more on one or more of these types of bikes in 2012 to further investigate the genre, but until then, my mind has not been convinced that it is a good thing in more than a few unique circumstances, which, as I say, isn't what goes for "All Mountain" in most folks minds.

MG said...

I'll vouch for Redstone's comments, as it was his bike I was riding... It's a ripper in the Rocky Mtns.

MG said...

... just read your most recent comment, G-T. Yeah, I agree with you there. My thought is that 17.5" is about the sweet spot for me. Good handling, balance, clearance and function without compromises. Get much shorter than that (than 17.3") and things start to get a bit hectic, engineering-wise, it seems.

Miles said...

I guess defining what I mean by short is probably a good idea, on the terrain that I ride I don't see a need for anything less than 16.75 or about 425mm. I've ridden and owned a few bikes with 445 or so chainstays and thought that they just weren't as much fun to ride on my terrain as bikes with shorter stays and overall wheelbases. I have a couple of bikes (26", cross, 29er) that have stays in the 425-435 range and they all do it for me. Thought It's also worth noting that the stays cannot be thought of in a vacuum, the seat tube angle angle and...uh....basically everything else, bottom bracket drop, headtube, front center, effective top tube, top tube length; all play a pretty big role in things as well.

Head Honcho said...


Karate Monkey.

cough cough.


Matt said...

I have recently switched to a 29er and the primary characteristic I have noticed is that it is really hard to get it around the sharp corners on our firetrails. In general, the bike feels very skittish on "loose over hard" conditions, which is what we have here. 29ers are everywhere here and all the owners I have spoken to have noticed the same thing. When I switch back to my 26er, I can move the back wheel with my hips, which I can't do on the 29er. My theory is that on loose over hard, the only way to control a bike is from the back wheel. Let the front over/under steer and push the back wheel around with your hips. This style of riding is impossible on my 29er (el mariachi). Having worked this much out I thought "oh - that's why people want shorter stays on their 29ers - so they can push the rear wheel around more easily".

This is not about gnarly, technical, scary trails. I am talking about big, wide, relatively smooth firetrails where (from what I have seen) 26ers are much, much easier to control.

Of course you get a benefit for this trade off, getting back _up_ those loose over hard hills is much simpler when you can just plant yourself in the saddle and grind up. On the 26er one is struggling to find the balance point which keeps the front wheel down without unweighting the back too much.

I have a 26er which strikes a wonderful balance. The back wheel is tucked in tight, the head angle is slack-ish but it only has 80mm of travel. I love that bike :) I think there is room in 29er land for this kind of bike (ragley TD:1 for example) to be done really well because the larger wheels partly make up for the short travel.

Guitar Ted said...

@Matt: With anything, there are compromises, of course. One has to decide whether the benefits outweigh those drawbacks. 29"ers are not for everyone, as I've said all along, but I do have one comment.

In your situation, I think a heavier hand on the front brake is maybe what is needed. Sounds like you've got the rest figured out.

The increase in front brake can "lighten" the rear enough to swing it around easier. That said, you would benefit from a shorter chain stay there.

Matt said...

That's a good idea for unweighting the back wheel which had not occurred to me. However, it won't work on the tracks I am thinking of because the front wheel will just wash out. I agree wholeheartedly with your point about tradeoffs. Around here we are beset with these twisty loose-over-hard tracks and yet the place is crawling with 29ers, why? They go up so darn well. The long twisty uphills are a joy on these bikes and I never need to go faster _down_ the hill :)

I am just really surprised that the discussion so far has been about steep and technical terrain. While for me, the long wheelbase is most troublesome on the most benign of trails - the big open firetrails.

chainline said...

Interesting discussion. I have this dilemma currently but with full suspension.
I am looking to build a Nicolai AC29 which Guitar Ted recently tested and enjoyed, but with the ability to use a stiffer 140mm fork with a slacker head angle, adjustable so I can find the right compromise.
My dilemma is, as G_T stated in the review, the geometry doesn't look conventional at first glance but seems to work well. The current vogue even for full suspension is to go as short as possible on the rear chainstays and it does cause complications and difficulties with travel and front mechs.
The chainstays on the AC29 are naturally 462mm, will allow a 2.5" tyre easily. Any shorter and I have to start offsetting seat tubes and compromising on tyre sizes, adding weight and gearing complexity.
The only other similar bike geometrywise is the Turner Sultan, interestingly Mr. Turner has similar views on the merits of straight tubing, stiffness etc. as Nicolai? All others have eschewed that length in favour of curvy tubes and sub 453mm chainstays.
So to my dilemma, I, personally, am not sure of the impact the extra 10mm of chainstay has on the bikes ability to negotiate tight switchbacks, they aren't on every corner to try out.
I need an 'all mountain' bike in the way described. I like to race Enduro in Europe where there are fast flowy singletrack downs with some tight switchbacks but also 2000m a day of climbing. So a compromise has to be reached.
The longer chainstay does result in a slightly more centred body position on paper with an easy ability to get weight over the front, an important element in cornering grip and the unweighting of the back as discussed earlier. The overall wheelbase is also an important factor, which in this case can still be kept lower than an equivalent 26" freeride type bike and only 10mm longer than my current 26" Helius AM bike..
It may not manual as easily, but I don't have too much call for that on the trail out of necessity, 'just because' well that's different!
Do those chainstays make it more stable at speed for a given head angle, probably, and that is important for maintaining speed whilst keeping the steering swift.

Ahh if only there was only one answer....

So what to go for, still not sure but I have to decide soon. Is designed to be able to back to standard if all else fails!

I think in summary, I agree with G_T, and I'm paraphrasing here not quoting; that it's the sum of the whole that dictates the quality of the ride not any one number..trouble is that doesn't help me pin the tail on my donkey...

'actual moutntain' biker said...

What is your all mountain experieince?? I have been riding bikes in the mountains for about 30 yrs. You do not seem to know much about what you post? How often do you ride in the mountains?? It seems like gravel roads are your specialties. Well, at least we know. All of theis e-expert internet review stuff is getting worse by the release. \rant.

Guitar Ted said...

@'actual mountain'biker:I get to ride on what you might call a mountain about twice yearly, but it doesn't take a mountain to find yourself on steep, demanding trails. However;I understand that many folks will not listen to an opinion if it doesn't come with the "proper credentials", whatever those may be for you or anyone else.

To that end, you need not bother with anything I have to say if where and how I ride doesn't "qualify" my opinions as valid to you. I am okay with that. But, you did comment, which shows.......something.