# Descending a C-50



## ciclisto (Nov 8, 2005)

I just got some new Mavic elite wheels for my C-50 question is, on descent i notice a lightness to the front and the wind takes it easily to the side. I descend on my steel bike with no fear perfect stability. is there any opinion to what may be set up incorrectly, I am 5.11" using a 57 frame traditional. bar has a three inch drop but am using spacers. Any ideas would be appreciated. Is this too light for me?


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## filtersweep (Feb 4, 2004)

I highly doubt it is the weight that it is a problem--- your distribution shouldn't be that radically different.

I notice a big difference between wide bladed spokes, and standard spokes in a crosswind--- and deep rims also make a difference.



ciclisto said:


> I just got some new Mavic elite wheels for my C-50 question is, on descent i notice a lightness to the front and the wind takes it easily to the side. I descend on my steel bike with no fear perfect stability. is there any opinion to what may be set up incorrectly, I am 5.11" using a 57 frame traditional. bar has a three inch drop but am using spacers. Any ideas would be appreciated. Is this too light for me?


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## tmluk (Sep 19, 2005)

*Similar curiosity*

I have a similar question myself. Not from experience (not a ww) but more of academic curiosity. I plan to ask this question in the weightweenies forumn. My question is ...

The science of why the bike stays up ... Is it partly due to the centrifugal force/momentum of the wheel spinning? Force/Momentum equations involves mass, recalling from my university days. So if one takes the limit of mass approaching zero, how would the bike stays up.

I am curious more from the science perspective, as the cycling industry continues to lower the weight of the bicycle. How an ultra-light (weightless) bike would handle ... stability, momentum, steerability, center-of-gravity, etc.


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## ciclisto (Nov 8, 2005)

my thoughts have been similar, when on a time trial course that is perfectly flat it seems my old steel once rolling really keeps up the steam. i.e. a body in motion tends to stay in motion. (newton law #?) but light wheels definitely help in climbing. But then drag etc enters, I really would like to study an informed opinion on this also. Some older lbs guys have mentioned in the past, in passing, you do not want too light it decends poorly , this is the basis of my question, are they correct?..................thanks, by the way the new wheels are for climbing but you have to come down!


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## C-40 (Feb 4, 2004)

*no such thing...*

The bike is a very small part of the total bike and rider weight. Whether the bike weighs 17 or 15 pounds makes no signficant difference in descending stability. Wheels with bladed spokes may catch a bit more wind, but the spokes on the Elites have far less cross section than aluminum spokes on the SSC SL or ES models that I use.

The steering geometry on a Colnago tends to be slow and stable. In this size, the head tube angle is only about 72 degrees and the steering trail is a generous 65mm. A Colnago will have more resistance to turning at high speed than most other racing bikes.

Your problem is probably two fold. You're used to your old bike, which may have even more steering trail and slower steering, so the bike feels less stable than you're used to. You may also have the new bike setup with too little weight on the front. Has the saddle been carefully positioned to place you in the same position, relative to the BB as the old bike? There are several common methods of adjusting saddle position that will at least get you in the ballpark. www.coloradocyclist.com/bikefit

Is there really a handling problem, descending down a straight road, or does the bike feel strange in a high speed corner? Not feeling planted is a vague complaint. Perhaps it's just the much stiffer frame's response to bumps in the road that has you spooked. 

I owned a 54cm Colnago C-40 when I first moved to Colorado and started riding mountain descents with hairpin and S curves, that I negotiate at 30-45 mph. I found the bike very stable, but the steering was too slow and resistant to change direction for my taste. FWIW, the bike, with me on it only weighed 152 lbs, so lack of wieght did not cause instability.


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## ciclisto (Nov 8, 2005)

I will attempt a more specific symptomatic discription. My old steel is a slx/sp probably 21+lbs with new mavic open pros. when I started with the c-50 I had open pro mavic on dura ace also. then I put the elites on a month ago. The decending I do is on practically perfect smooth new pavement. very fast downhill with some slow sweeper type corners. It is the straight line decending when i just want to let it go that the front seems too light as if not weighted enough and the wind does take it sideways easily. As for position I am pretty much spot on both bikes although they are very different, I even had a fit session on the C-50. maybe my not being on the drops at all times is a factor? It just may be my being used to the old cadillac. Although I had a litespeed for a while and it was worse.


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## C-40 (Feb 4, 2004)

*ride in the drops...*

If you put a scale under the front wheel, you'll find that two things have the greatest affect on the weight placed on the front wheel. One is saddle position and the other is torso angle. Moving the saddle forward increases weight on the front and so does riding in the drops. You'll also have better steering control in the drops. Another thing that I learned quickly from negotiating hairpins is how to steer a bike accurately. Most of us do it with little thought to what makes a bike turn, until we get into trouble and make the wrong move. At high speed, a bike turns to the right by pushing on the right side of the handlebar. The bike then leans right and turns right. Just like a motorcycle, a bike is NOT steered with body english or weight shifting. I learned the hard way when my bike kept drifitng toward the centerline that I had to push harder on the right side to sharpen my turn. Now it's intuitive after a few hundred trips down the mountain (haven't crashed yet). I took a motorcyle training course a couple of years ago and it's the first thing you learn. If you fail to push hard enough on the proper side of the handlebars, a motorcyle will go in a straight line. Many accidents are caused when a rider panics and quits pushing on the bars in a corner. The result is a bike over the centerline or off the shoulder.

I always stay in the drops during a serious descent with lots of corners, or if I have the potential to be exposed to substantial side winds. I rode yesterday in very windy conditions and got front wheel sway in some extreme gusts, so I didn't even think about venturing into the mountains. Some days it's just better to avoid high speed descents. 

I doubt your Elite wheels are the problem. They're not that much different than a common open-pro hand built.


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