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· Failboat Captian
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Discussion Starter · #1 ·
As of about 8 months ago, I now have 2 road bikes. My 1st is a nice Klein Q Carbon Race, and last November, I bought a dedicated commuter; a ChrMo steel, cheap single speed with bullhorns.

As I talk about geometry here, I'm referring to steering geometry, not fit.

The geometry of the SS seems a lot more stable. Slack HTA, lots of rake. Typical old school steel frame looking geometry.

The Klein is very upright, with a steep HTA and straight forks with dropouts in the center of the forks. Very typical race looking geometry.

The Klein, which is intended as a "race" bike, and therefore, one would surmise, built for speed. Yet this bike is orders of magnitude more twitchy than the slack steel frame. Now, don't get me wrong, the Klein can get up to speed. I've had it up to 59.9mph once and 50 a couple of times, and it handles pretty well, although I have had one serious case of the wobbles when pulling a pack at about 28mph once (pretty scary, but my fault, as I was resting my arms on the tops of the bars).

Although I've never had the steel bike up to those speeds due to the fact that it's a SS, and I haven't been on a hill capable of pulling me down it at 50mph, it seems it would be a lot more stable at those speeds.

So why is it that "race" bike geometry is so much less stable at speed than classic geometry? It's not like the steel bike couldn't slalom any less quickly, so it doesn't seem that actual quickness to make a turn or avoid an obstacle or someone else's bars or rear wheel would be a problem. And when I get out of the saddle to hammer the SS up a hill, it's a lot more compliant than the Klein. Hell, now, every time I get out on the Klein, it takes me a half hour or more, just to be able to get out of the saddle at all, without having the bike feel like it's going to get flung sideways from under me. I also find myself pulling wheelies when starting from a stop due to the shorter chainstays.

It just doesn't seem to make logical sense to me. Can someone 'splain the thought process behind the handling geometry?
 

· yup
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Sounds more like a crit geometry, standard race geometry isn't usually that twitchy like you describe. My old Cannondale Crit. 3.0 is just like that, but my colnago road race geo. is much more what you might expect. Also if it is shimmying at 28 mph, that is a concern regardless. something might be out of alignment.
 

· Failboat Captian
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Discussion Starter · #3 ·
tferris said:
Also if it is shimmying at 28 mph, that is a concern regardless. something might be out of alignment.
That was a one-time event in the 5+ years and 4000+ miles I've owned the bike. I was resting my arms on the tops, and starting to come out of that position due to whatever I was approaching. As I took my arms off, I guess I didn't take the pressure off both arms evenly and didn't have enough weight on the front wheel. I got it back under control in 1-2 seconds.
 

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I don't believe it's all geometry. My steel Colnago is a race bike and has never been anything but stable at any speed or road condition. I have had speed wobble with my old steel Raleigh Super Course MKII. It is a more relaxed geometry than the Colnago. That is just the opposite of what you have experienced. I think frame material and construction have a lot to do with stability along with geometry. But I'm far fron an expert on the subject.
 

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JohnnyTooBad said:
That was a one-time event in the 5+ years and 4000+ miles I've owned the bike. I was resting my arms on the tops, and starting to come out of that position due to whatever I was approaching. As I took my arms off, I guess I didn't take the pressure off both arms evenly and didn't have enough weight on the front wheel. I got it back under control in 1-2 seconds.
PIO = pilot induced oscillation. Some sort of control input which caused a harmonic oscillation.
 

· Failboat Captian
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Discussion Starter · #7 ·
It's not the one-time wobble that I'm focused on. It's the fact that when I get on the Klein and get out of the saddle to hammer, it seems to want to turn all over the place. It's just twitchy. (edit - this is low speed stuff I'm talking about - under 20 mph)

Looking at the photos I provided, it seems like it's more a product of the rake in the fork than the HTA, as the HTAs don't seem to be that hugely different, but the bend in the steel fork pushes the front wheel in front of the line of the head tube much more.
 

· Banned
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Very weird- my Klein Q-pro is insanely stable and balanced- I've never found it twitchy at all.

Is your stem to short/long?
 

· Failboat Captian
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Discussion Starter · #9 ·
Interesting thought. I've gone to a couple different length stems. Just before I bought the commuter last fall, I put a 90mm stem on it, to replace a 120mm stem. Didn't notice any stability issues at the time, and like I said, after a while of riding it, I get used to the geometry, and it's less of an issue. I really notice it when I get out of the saddle, because on the commuter, I can push or pull on the bars, depending on where my weight it, and it doesn't affect my trajectory. But on the Klein, if I'm not really careful about keeping weight on the bars, such as if I start to pull on them for power, the bike wants to turn hard. I think I have always (even with the 120mm stem) had to pressure the bars when climbing, or at least stay neutral on them. I don't think I ever attempted to pull, because I could tell what would happen.
 

· Banned forever.....or not
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What are the actual numbers for the bikes. The words "race geometry" means little.
 

· waterproof*
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Yep, there's more to it than labels or fork measurements. BB height, chainstay length, center of gravity, wheelbase, stem length, yada yada.

But I agree with the OP that a "twitchier" bike is not better, though a lot of cycling lore would have riders believe that. I think it's related to equating a parking lot test ride with real world performance; which it's not.
 

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I have often wondered the same thing. Let me pose the question a little differently.

My rainy day bike is an old (25 yrs?) lugged steel bike and has a longer wheelbase than my regular ride (2003 steel Lemond). The new bike definitely feels more solid but it is quicker in steering. In some respects the straight line stability of the old bike makes a more comfortable ride than the new bike; so why do new (better) bikes have quicker steering?
 

· Gruntled
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Creakyknees said:
... I think it's related to equating a parking lot test ride with real world performance; which it's not.
I think you might be right. Or, it's a flawed analogy with cars: a Porsche 911 has quick steering, a Cadillac Eldorado has slow steering, so quick steering must be faster. As the OP pointed out, the additional effort required to steer a bike with more stable geometry isn't that much. I can't imagine losing a race because my bike's handling was too slow - maybe a track sprint, but not a road race.

Further, I think the manufacturers are catching on: notice the popularity of the Specialized Roubaix and the Cervelo RS, both of which have longer wheelbases than "traditional" racing bikes.
 

· Failboat Captian
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Discussion Starter · #16 ·
tferris said:
Off topic but how do you like the bullhorns?
I like 'em. Very comfortable. More comfortable than being on the hoods of drop bars, with better braking power from that position. But I have to admit, sometimes I'd like to be down in the drops when there is a headwind. But this bike is stable enough that I am very comfortable being on the virtual aerobars (resting my forearms on the tops), which I won't do on the Klein anymore. Another thing I like about the bullhorns is that they have a bit of an ergo bend as the bars come away from the stem, they bend down. It's very comfortable. Better than if you took regular drop bars and flipped/chopped them. And because they used a full length of bar tape when they built the bike, the tape is thicker, and therefore more comfortable.
 

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Gut instinct... I have a feeling that part of it might be in the choice of bull bars. Like a longer stem, they'll have your hands farther out from the axis of rotation for your fork. If the drop bars had been mounted in a similar position, hands-position wise, it might feel more stable. Closer to the steer tube makes for a twitchier ride, says the guy who used to have a 50mm stem on his mtb...

That's just me talking from the other end of the intestinal tract, I'm sure there's probably more to it than that...
 

· Failboat Captian
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Discussion Starter · #18 · (Edited)
As far as actual geometry, I was unable to get the numbers for the Klein. They have a tech manual for the '03 bike, but nothing that gives the specs. MAJOR EDIT - I found the specs for the Klien

Commuter ('07 SE Lager) 61cm:
TT = 570
HTA = 72
STA = 74
Chainstay = 409
BB height = 282

Klein '03 Q Carbon race
TT = 605 (effective)
HTA = 73.5
STA = 72.5
Chainstay = 414
BB = 265
Wheelbase = 1025
rake = 43
trail = 56

The Klien actually has lower BB, much longer TT, longer chainstays, but more laid back seat tube angle. But the commuter has a more slack HTA. The SE web site doesn't list trail and rake.

I guess, what it all boils down to, is that the Klein was my first road bike, and now I've had the opportunity to ride some significantly different handling bikes. If/when I ever decide to get a new geared road bike (I still like my Klein a LOT), at least I'll know what sort of feeling I like better, and how to test ride. Unfortunately, I won't be able to simply look at the numbers and be able to instantly know what I would or would not like, which means I'll have to be able to test ride. And what I found in the searches I've done for bikes in the past, is that finiding a model that I want, in a 61cm frame, to test ride, is pretty close to impossible. (another reason it sucks to be tall)
 

· Failboat Captian
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6,559 Posts
Discussion Starter · #19 ·
uber-stupid said:
Gut instinct... I have a feeling that part of it might be in the choice of bull bars. Like a longer stem, they'll have your hands farther out from the axis of rotation for your fork. If the drop bars had been mounted in a similar position, hands-position wise, it might feel more stable. Closer to the steer tube makes for a twitchier ride, says the guy who used to have a 50mm stem on his mtb...

That's just me talking from the other end of the intestinal tract, I'm sure there's probably more to it than that...
I might swap back to the 120mm stem, just for a test ride, to see how it feels, but when I'm out of the saddle, I'm almost always at the ends of the tops, where they bend forward, on both bikes.
 

· your text here
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it takes you that long to re-adjust your riding when switching bikes?

i used to think people were making it up when they said frames felt "quick," "stiff," and "responsive." that all changed the first time i got on my AL build. i about decked it when i tried to Uturn at a place i could always Uturn on my old bridgestone. that was when i really understood that different bikes have different characteristics. the AL bike is light, quick, stiff, smooth in the corners, and sometimes twitchy/"responsive" if im not watching it. the bridgestone is heavy, compliant, wants to go straight, takes a bit to get rolling and very comfortable. my new steel salsa is somewhat light, not too stiff or compliant, not too quick, and i can ride it all day. kinda my goldilocks.

the AL bike is good for quick neighborhood crits. the salsa is good for longer weekend rides. the bridgestone is now a fixie with a rack and saddlebags, so its good for anything.
 
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