top tubes -Level?
 

I have a Pinarello Montello about 1987 with a replacement fork-Tomassini-about the same era.I took a level today to see if the top tube is level and it's not.about 3-4 millimeter sloping upwards towards the front.Were top tubes level on these italian steel racing bikes?Should I have a fork with a longer rake?

Out of curiosity, does it look as if the tube is sloping? I'm not sure I'd be able to visually detect a 3-4 mm slope in a top tube. I don't have answers to your questions.

I have the same era Pinarello, a 57 center to top, I can measure it for you. rake and length.

There were no standard lengths. Builders did what they felt worked in their minds and this was before "forks-R-us" buyout carbon forks encouraged some uniformity.

In general bikes were designed with a level top tube in mind, but I have a few and seen many examples with factory components that did not have a level top tube.
A 3 to 4 mm difference will probably translate to .25° change in head angle as a rough guess.

yes it looks level.I put a level on it and if I lift the level a couple of mm on one side the bubble goes between the lines,signifying exact level.I was thinking however that since there is some play for the wheel in the back dropout,true level would be very rare.

Uhmmm..IIRC, some steel bikes in their smallest sizes tend to have backward sloping tubes because there's no head tube left to shorten to get the TT level..
What size is the Pinarello you are looking at??

I would really like that so I would know how close to original is my fork.Also if you could measure the closest distance between the front tire and the down tube,I'd be interested.Mine is exceedingly close.About 1 centimeter.Slightly less at the back wheel!Does your toes hit the tire sometimes?

make sure the floor is level too!

Mine is 54cm.That's C-C.

A headset that is 1mm thicker on the bottom cup than the builder designed the frame for could cause this even. And since you have a replacement fork I would say that that is likely responsible. The height on the fork is likely different by a mm or two. Different fork crowns are different thicknesses, which means different height forks and the frame was built according to that particular fork... So I am not surprised. You should be pleased that the difference is so minuscule and you have such a closely matching fork.

If you gotta have it level, face the headset flat on the fork down a few mm.

Smallish...but not enough for a top tube to go sloping funny. I might expect such on maybe a 48CM and smaller size frame...., so small size is most likely off the list of possible causes.......I think I agree that it might have something to do with the possible replacement fork on the frame then....or the headset configuration/design.....

There's about 6mm of height variability in a horizontal dropout too.

Fork's bent!

(Just speculation. Pictures would help.)

P.s. You may get a more accurate measurement by taking the distance from top of the top tube at the head lug to the floor and again at the top of the top tube at the seat cluster to the floor than by lifting the bike to match the level.

Excellent point also.

I'm glad for your sake it appears I was wrong. Looks straight enough, though it's not easy to tell from the slight angle of the photo. Shorter bikes do tend to have more issues with toe overlap. Hopefully someone who owns or is more familiar with this model can show an example of an original fork for rake comparison.

1989ish 54cm Montello. This may help.... And no, the fork's not bent.

http://i257.photobucket.com/albums/h...10kevin007.jpg

I doubt "level" meant 0.00 degrees of variance from true level.
If it rides fine, I wouldn't worry about it.

It's not like it means you have a climbing angle of attack or anything.
If it sloped down, you wouldn't be going any faster, either.

Run a 700x20 at the front and a 700x23 rear, and you should be fine.

But if you do this, be aware the top of the steer tube will sit up higher above the top of the head tube - could need more spacer for the top half of the headset.

My Pinarello front dimensions:

585 mm direct measure BB center to front axle center.
46 mm rake.
360 mm front axle to crown race seat as measured parallel to the steering axis.
43 mm tubular rim to down tube at the tangent (closest distance) I chose the rim vs the tire as tire size varies much more than rim diameters.

hehe.. Devil's advocate. I am sure Wulf suggested this tongue in cheek, because this would be insane.

Let me ask you forum member... when was the last time you checked to see if your top tube was perfectly level on a perfectly level surface plate? I would be very surprised if any of my top tube are perfectly level given all the variables that go into it.. tire variation, pressure, headset type. position of rear wheel in drop outs... small variations in the construction that are inconsequential... etc.

I use the axle centers. Most are. A number are not. Some rise as much as 8 mm between the seat lug and the head tube. These are for the most part middle size range frames.
Note that if the frame was designed with a "Nuovo Record" steel headset and one exchanges it for a Super Record, you will be off.
I set in almost all cases the rear wheel at the forward most adjustment of the rear dropouts.

Thank you for your efforts!!My measurements are less all around but the bike is also smaller so probably that's the reason.Thanks to all who contributed to the subject.