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Technical FAQ with Lennard Zinn: Living by the rules

  • By Lennard Zinn
  • Published Feb. 23, 2011
  • Updated Feb. 24, 2011 at 10:00 AM EDT

Q.Dear Lennard,
For the first time this year they’ll be available to consumers everywhere.”

So how does this revelation of $250 tires that were only available to Lance reconcile with the UCI rule that’s been on the books since at least 1999 that says all bicycle equipment used by professionals must be available to the general public?

This is just one of dozens of examples of a rule the UCI doesn’t enforce because of either incompetence or corruption.

2000 – 2011 UCI rules
1.3.007
Bicycles and their accessories shall be of a type that is sold for use by anyone practising cycling as a
sport. The use of equipment designed especially for the attainment of a particular performance
(record or other) shall be not authorised.

1999 UCI rules
1.3.004
Bicycles shall be of a type that is or could be sold for use by anyone practising cycling as a sport. The use of a bicycle designed especially for the attainment of a particular performance (record or other) shall be not authorised.

—Phil

A.Dear Phil,
Judging by this press release from last November, it appears to be in conflict with the UCI rules, as it is a new offering from Hutchinson for 2011.

However, VeloFlex makes those tires and has similar (maybe even the same?) models under its own brand.

I’m waiting to hear from Hutchinson France on this issue.
—Lennard

Q.Dear Lennard,
There seem to be a lot of tubular questions popping up at the moment, and here’s another bunch. Do you see any merit in using the ”Belgian taping method“ on road tubulars?

I understand that road tires don’t get anywhere near the same abuse as `cross tires, and the pressures are higher with less lateral forces, but can it hurt to get them on there really well?

What would the disadvantages be? More weight?
—Chris

A.Dear Chris,
I wouldn’t do it. The smaller diameter (for better fit in the rim bed) and the higher pressures of road tires add a lot to the strength of the bond that holds the tire on the rim. And the smaller tire diameter means less leverage yanking them off. I also think that the extra weight and extra energy loss from all of that stuff under the tire is not worthwhile on a road tire. I stick to the old school method of gluing road tires.
— Lennard

Q.Dear Lennard,
One of my juniors crashed his bike at Valley of the Sun – he runs 2002 Campy Chorus 10-speed.

The right shifter lever broke the pin that works as the quick release. Easy fix would the replacement part but none seem to exist…

As an alternative, we have a set of 7800 DA shift levers & rear derailleur, but are not sure if that set-up is compatible with the 10-speed cassette from his chorus stuff? We are willing to give him the Shimano shift package, but would we also now need to swap out his wheels?
— Dan

A.Dear Dan,
All he really needs is the quick release pin. Unfortunately, you have to get the entire lever blade assembly, and the quick release pin is part of it. Unfortunately, you can’t get a Chorus blade assembly. In the QBP catalog, the closest he can do is LD9041, which is an 2001-’03 Record right lever assembly and will set him back at least $100, maybe $150.

Failing that, lots of shops have broken Campy levers sitting around; I’d look for one of those to rob that part from. I know my nearby shop, Louisville Cyclery, often has some old Ergopower levers in a box I can cannibalize.

The Shimano stuff would not be compatible without switching to a Shimano or SRAM cogset, thus requiring a different wheel or freehub body.
— Lennard

Feedback on Feb. 15 column:

RE:Dear Lennard,
Hey in your response to Angus you say “A 56cm frame with a 56cm top tube and a 74-degree seat angle has a much longer effective top tube than does a 56cm frame with a 56cm top tube and a 72-degree seat angle.”

Okay, so unless I am mistaken, for the same seatpost height from the center of the bottom bracket, and the same stem length, how can a 74-degree seat tube produce a longer effective top tube if they are measured on the horizontal intersection of the seat tube extension to a line in the center of the head tube?

Any seat post/height beyond this measuring point will push the seat further away from the head tube on a 72-degree angle seat tube post versus a 74 angle. When you have the same seat tube length, but a slacker seat tube angle, you are increasing the effective top tube length compared to a steeper seat tube angle (which would place the extended seat post closer to the head tube). Are we just talking about different concepts?
—Scott

A.Dear Scott,
The answer to your first question is yes if you mean “horizontal top tube length” when you say “effective top tube length.” But that’s not what I meant, so the answer to your second question is also yes, we are talking about different concepts.

Our sample bike with a 74-degree seat tube.

Judging by the flood of emails I received on this subject, I’d say that there are three issues to address: one of nomenclature, one of concept, and one of looking at frame geometry from a different perspective than I do. Certainly in your question, the definition of “effective top tube length” is an issue. And it’s hard to tell from your question, but definitely from some of the other ones about this, there is widespread misunderstanding about what changing the seat angle does to bike fit.

In talking to others around the office, they have a hard time understanding my reasoning as they seem to think of the bottom bracket in the same position relative to the head tube, as if the head tube/down tube/bottom bracket is a single unit and can only see that a slacker seat angle requires a longer top tube, even though I said the top tube length was fixed. But I think of the top tube length as fixed and envision swinging the bottom bracket forward or back by the angle changing up at the seat tube/top tube intersection. It is from that perspective that in my response to Augis I was describing two bikes with the same top tube length but two different seat angles. I wrote: “A 56cm frame with a 56cm top tube and a 74-degree seat angle has a much longer effective top tube than does a 56cm frame with a 56cm top tube and a 72-degree seat angle.”

Here is the same bike, but with a 72-degree seat tube.

So first, to define terms. By “effective top tube length,” I was referring to how it fits the rider, NOT to what you measure with a tape measure on the frame. I’ve been using this term since before up-sloping top tubes, which brought with them the requirement for more definition of “top tube length.” The top tube itself in a “compact” or “sloping” frame is shorter than the “horizontal top tube length” measured from the head tube/top tube intersect to the center of the seatpost. Since the actual top tube length measured along a sloping top tube is meaningless, I mean “horizontal top tube length” when I say “top tube length,” no matter whether the tube slopes or not. However, plenty of other people mean “horizontal top tube length” when they say “effective top tube length;” here is one example. So, clearly, I had better come up with a better way to describe what I meant in my answer last week. First, let’s now make sure we all are in agreement about the concept.

I responded to Augis the way I did because the bottom bracket is further back relative to the top tube/seat tube intersection with a 74-degree seat angle. The bottom bracket being further back means that you have to push the saddle further back on the seatpost to achieve the same position of the saddle relative to the bottom bracket center as you would on a 72-degree seat angle. So the reach from the saddle to handlebar is effectively LONGER with the steeper seat angle, thus making the top tube length equivalent to a longer one on the 74-degree (or to a shorter one on the 72-degree, however you choose to look at it).

Look at the two drawings. I drew one frame with a 74-degree seat angle and a 56cm (measured horizontally) sloping top tube that has the same head tube length as a 56cm frame with a level (non-sloping, traditional) top tube (also 56cm). You can see that with a 75.5mm saddle setback, the reach from saddle nose to bar is 575.5mm. I drew another frame, this one with a 72-degree seat angle and a 56cm (measured horizontally) sloping top tube that has the same head tube length as a 56cm frame with a level (non-sloping, traditional) top tube (also 56cm). You can see that with the same 75.5mm saddle setback (requiring pushing the saddle much further forward in the seatpost cradle), the reach from saddle nose to bar is now only 557.2mm – 18.3mm shorter. So what I was trying to express in my answer to Augis last week is that it is as if the 56/56 frame with the 74-degree seat angle has a longer top tube (by almost two cm – 18mm) than the 56/56 frame with the 72-degree seat angle. Capisce?

As for the terminology, I’m not sure where to go from here. I assume that we can all agree that making the seat angle steeper on a frame (without changing its seat tube length or horizontal top tube length) effectively increases the rider’s reach to the bar (as long as the saddle maintains its position relative to the bottom bracket). Since the angle is built into the frame, this has the same effect as increasing the top tube length and leaving the seat angle the way it was. This is why I call it “effective top tube length,” but since others in the industry simply mean “horizontal top tube length” by that, then we need to call it something else. “Effective reach” doesn’t do it, because it involves components as well as the frame. At this point, I don’t know what to call it to avoid confusion. Maybe “equivalent top tube length?” Any other ideas?
— Lennard

FILED UNDER: Bikes and Tech / Technical FAQ TAGS: / / /

Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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