|HEY C40!!!!||the bull|
Apr 8, 2003 1:23 PM
|Got a friend that I am going to build up a dream plus for.
I read this article once (probally 3 times) that says you should buy colnagos a little smaller then normal.The stem was to end up being 130mm or so!Normally I like to see a stem around 110mm or 115mm.But I am going to post the website with this interesting article.Please tell me what you think Because I trust your opinion.
|read it before, total BS....||C-40|
Apr 8, 2003 3:40 PM
|This has been posted before. The article is quite humerous. The person who wrote it doesn't know squat about fitting a bike.
He compares frames of completely different materials and comes to the conclusion that 1cm in size made a big difference in the performance of the bike. Quite a wild conclusion.
If you take a look at the true difference in the fit of the two frames sizes, you will find that there is no justification for a significant change in stem length.
The idea that stem length makes a big difference in weight balance is also misguided. For the most part a longer stem just moves your hands forward. Weight still has to be transferred to the frame through the steering tube. Weight balance is affected more by the saddle position, chainstay length and wheelbase.
I've compared sizes 52 through 54 and can make any of them fit the same with a change in stem length and angle. The smallest size will have a little shorter wheelbase and more weight on the front wheel. I've owned a 54 and a 55, but I could ride as small as a 52. The 52 would require a 10mm longer stem flipped at a 96 degree angle to get the bars to the same position as the 54. If 2cm of spacers were used under stem, then a 5mm longer stem would produce the same fit on the 52 as the 54. I'm not wild about high rise stems or spacers, so I see no point of buying a 52 instead of my 54.
I pay attention to the head tube length to be sure that I can get the bar height that I need without an ugly stem setup. Calculating the change in reach must take into account any changes in the seat tube angle. On midsized frames, it quite common to find two sizes that have slightly different STA and the same effective TT length, once the difference in saddle position is calculated.
A common example is a 55cm Colnago with a 74 STA and 54.3 TT. It will fit the same a 55cm Litespeed with a 73 STA and 55.5 TT.
|Thanks again C !||the bull|
Apr 8, 2003 4:22 PM
|I will pretend like I never saw it.
He seemed like he know what he was talking about with all his experience but it did not really make sense to me.
Apr 8, 2003 6:58 PM
|How does Tom "not know squat?"
I'm not attacking, which is worth mentioning given some posts of late. Nonetheless, Tom is a reputabable road and tri dealer in the upper tier. His experience speaks for itself even though some might not agree with this evaluation of the 'Nago in question.
Likewise, based only (and admittedly) on pictures of him, I'd guess that's he's got more height in his torso than his legs. That said, it makes sense that he'd favor a longer stem.
I think this article speaks to the nuances of the ideosynchrocies of fitting a Colnago. Frankly, I wouldn't dream of realying on Wrenchscience's or CC's fit paradigms's for 'Nago's frames. Their/his frames are simply too different to rely on simple fit equations.
Still, Tom harldy qualifies as somebody who "knows squat." Rather, I think he wrote the article based upon his experiences. I'd wager to guess that a client in his shop would be fit according to the customer's dimensions.
I'd really appreciate your comments....
Apr 9, 2003 6:30 AM
|I was sized on a serrotta size cycle.
I have also done the wicecycle fit on computer.
I think they are using the same formula.
because the recomended size was the same.
They seem to work good in my opinion.
the one thing that still makes me wonder is the STA(seat tube angle).
I use a seatpost has no setback.
The guy who fit me on the serrota said that I would benifit from a a 74.5 STA.
But I have been on a 73(Litespeed classic)and my plum line falls just behind the axle (the seat is right in the middle)
and I dont think I have a problem.
They also wanted to give me a TT of of 58cm with the stem being 115.So when the Litespeed I ordered had a TT of 57.5 I put on a 115 cm stem.
Anyways I think you can use the size formula and get your
overall length then get a frame and proper size stem and this should work pretty damn good.
I should post a pic of me riding my bike and see what you guys think.
|One word about professional fittings...||Fez|
Apr 9, 2003 8:27 AM
|They are obviously only as good as the person who does them. And even if the fitter is proficient, the fit is just a guide for you, not the gospel. You will know what is best for you.
I think arguably the most important and difficult part of the fitting is the saddle fore/aft position.
The fitter has to set up everything correctly and take the reading accurately. If he is looking at a wrong angle or does just one thing wrong, it can throw the reading off.
Also, it depends on so many other little things - like proper saddle height, cleat positioning, and the slightest shifting of position on the saddle. And even then, neutral KOPS is still just a guide - there is no "optimal" position - it could be +/- a few cm either way.
I went to get my fit looked at by the store owner. He is a Serotta dealer and is Serotta certified. Everything was OK until we got to saddle fore/aft and he was just dead wrong in getting an accurate measurement. He told me my current ride (standard 73 STA) was so inadequate and I needed a special custom 75 degree seat tube angle.
He was either 1)dead wrong or 2)just trying to scare me into ordering a custom Serotta. Either way, it was bad news because I would still be messed up if I listened to him.
As it turns out, my 73 degree seat angle with saddle centered on the rails produces neutral KOPS and I could easily go further back if I wanted to, but I prefer a little easier spin. His recommendation of 75 degrees would totally be f'd up. Six months later I would be arguing with him and Serotta to build me a new frame. There have been other stories (like the toe overlap one) where people try to reinvent the wheel when going custom and basically create new problems when they think they are solving one.
Fit has to evolve over time to see whats comfortable. People who order a custom frame without knowing this, or people who place too much trust in the fitter are setting themselves up for a problem.
|correction I am using a 110mm stem om 57.5 TT.nm||the bull|
Apr 9, 2003 9:14 AM
Apr 9, 2003 7:15 AM
|If you read this article in it's entirety, it's clearly just an advertisement, intended to convince you that owning a Colnago will produce a riding experience unlike any another brand. I currently ride a 54cm C-40 and agree that it's a fine bike, but there is nothing magical about the geometry that makes it's fit or weight balance significantly different from many others. There is not a single word in the article that mentions how the saddle was adjusted, why the stem length was increased or values listed for the "magical" the front to rear weight balance.
After 23 years of bike fitting, you would think that a person would be interested enough to learn a little geometry and trigonometry, but apparently not. The author blindly accepts the ideas of the Trialtir representative, who's just another salesman. The faulty assumptions and misconceptions in this article are numerous.
"Colnagos are tricky to fit. They seem to have shortish top tubes and their seat tube measurement methodology is a little odd. It takes experience with Colnagos to fit Colnagos. I have learned a lot about fitting Colnagos by fitting my own Colnagos and mostly from Dave Koesel of Trialtir USA."
The statement above indicates that the author can't interpret a simple geometry table that is readily available from Trialtir. The table clearly shows both the center to top and center to center frames sizes. The center to center measurement method is as traditional as it gets. The entire frame design is reduced to nothing but lines and points. I don't see the mystery. It's extremely simple to compare Colnago geometry to any other brand. The idea that the top tubes are short is also incorrect. Short is a relative term that must include a comparison to the geometry of other frames. The TT length of Colnago frames is long in the smaller sizes and short in the larger sizes, compared to some other brands.
"What might fit a person correctly, may not be built with geometry that will interface with the road correctly."
The statement above is actually fairly accurate, although it would be more accurate if correctly was replaced with optimally. I'm not sure that there is a single correct or optimal interface with road. The optimal geometry for a flat criterium race would not necessarily be optimal for a long stage race with lots of mountain climbing and high-speed descents. If the author had noted a particular front to rear weight balance that he considered "correct", I would have had more respect for the article.
"Colnagos are designed to use an offset seatpost and a long stem that hangs the rider's weight over the wheels, not over the frame, which results in a short wheelbase and fast handling. The bike is planted. They just handle, like a Ferrari. The weight bias is perfect. That is how Ernesto Colnago intended them to be ridden."
The statement above is a mixture of fact and fantasy. The seat tube angle on the smallest Colnagos tends to be steeper than some other brands, and they do supply a seatpost with the C-40 that has a bit more setback than some others, but the larger sizes use the same 73 degree STA found on a dozen other brands. A long stem can only be used if the rider can tolerate the total reach produced, once the saddle is adjusted to the optimum fore/aft position. The total reach from the saddle to the bars can be proven to be no different than many other brands. The idea that using a longer stem applies a significantly larger amount of weight over the front wheels can easily be shown to be false. A properly positioned rider applies very little weight to the stem and a small change to a small weight is negligible. The statement about "hanging the rider's weight over the wheels, not the frame" just makes no sense whatsoever. As for "fast handling", Colnago steering geometry results in a greater amount of trail and slower steering than many other brands. It's great for long road races. The slack head tu
|keep goin!||the bull|
Apr 9, 2003 7:36 AM
|I think it cut off but this is good stuff.
By the way here are somd pics.Its hard for me to get a
in a postion I am happy posting because the camera shoots "when ever it wants".
|pic 2||the bull|
Apr 9, 2003 7:39 AM
|picture of me spinning||the bull|
Apr 9, 2003 7:41 AM
|What do you think of my riding position.nm||the bull|
Apr 9, 2003 9:21 AM
|What do you think of my riding position.nm||morency|
Apr 9, 2003 11:20 PM
|I'd try two things:
-moving your shoecleats to the front
but, the feel is more important than the look
I'd say no sore, no change...
|this pic is the best for plum line.||the bull|
Apr 10, 2003 3:43 AM
|oops, the rest....||C-40|
Apr 9, 2003 8:32 AM
|The slack head tube angle produces a larger front-center dimension and a wheelbase that is just as long if not longer than many other brands.
"With my new, lower standover height and lower center of gravity, withering attacks on uphills are possible."
Now here's pure fantasy. 52 and 53cm Colnago's have exactly the same BB height, so the only difference in the center of gravity would be due to the 1cm lower position of the top tube. This probably amounts to 1% or less and has no impact on climbing ability. Perhaps the author is experiencing a stiffer BB or just the general increase in stiffness that one would expect from an aluminum frame.
"The top tube of the bike was 4mm (that's millimeters) shorter. On the CT1 53cm I was using a 120 stem with no spacers underneath and had trouble getting a really good, low position in the drops (not that I use it that much anymore, nice to have though when you're struggling to not get dropped). On my new 52cm. Dream Plus I used a 130mm stem also with no spacers under the stem."
This changes noted above don't make a lot of sense if you review the geometry of the two frames. Although the TT length of the 52cm frame is 4mm shorter, the STA is also .5 degree steeper. If the author maintained the same position relative the to the BB as the 53cm frame, he would have moved his saddle back by 6mm. This would increase the reach by 2mm, not shorten it. No change in stem length would be justified. He doesn't even mention what was done to the saddle position. To maintain the same reach with the longer stem, the saddle would be moved forward 12mm. What happened to "hanging the weight over the wheels"? He also states that the larger frame did not allow him to get the stem low enough. Now there's a rare problem. I guess he doesn't realize that there are other brands of stems with less angle and shorter steering tube clamp heights that would lower the stem by the 1cm that was achieved with the smaller frame. From the picture, it looks like he has a saddle to bar height difference in the 10-12cm range. Darn few riders of a 52cm frame want more than 10cm of drop to the bars.
|That's a great rebuttal||sn69|
Apr 10, 2003 5:20 PM
|Lemme ask you this. Do you think Tom was writing this to speak "road" to triathletes? Dunno. I speak "tri" fluently and I believe Tom knows this stuff in that regard.
Anyhow, thanks for the well-thought-out response.
|not a technical writer....||C-40|
Apr 10, 2003 7:07 PM
|The author may be knowledgeable on some subjects, but he's obviously not versed on geometry or any technical subject as far as I can tell.
It just seems like an infomercial to me. These two guys togther wrote more baloney than I've ever read in an article without one shred of explanation of the "fitting" process.
I also liked the picture of the "stainless steel" dropouts on an aluminum frame! No way, the whole thing is aluminum.
I'm sure I could find more jewels of wisdom is I read some more.
|main differences in feel:||colker|
Apr 9, 2003 8:52 AM
|feel, not fit. a bike may fit the same as another and the later will feel better or worse. why? imho, front end length first, cs length second, bb height third. |
just saw a picture of mercxx sitting by his road bike before a tour stage... his front wheel is very close to down tube. almost straight fork, steep angle head tube, short front center. that bike will feel totally different from another with a longer front end.
|130mm looks nice to me||morency|
Apr 10, 2003 6:49 AM
|My bike setup has also a 130mm stem, looks nice to me.
I know here in Belgium when you buy a Merckx custom made, the stem is almost always 110mm.