Technical FAQ with Lennard Zinn: More on the legality of Lance's tires, Di2 brake compatibility, stack & reach and more

Published March 1, 2011 02:59PM

Here’s the answer I promised from Hutchinson regarding the UCI-legality of the Armstrong tubulars:

Dear Lennard,
Since this tire is made for us by another company that sells a very similar tire to the public, this is seen as a production item. Much the same as Radio Shack uses Lightweight disc wheels with Bontrager labels on them. Our tire is made to our exacting specs, but is similar in construction to the tires that the facility we use in Italy produces under their own brand. The thing about these tires is the ability to ride something limited and exclusive with a lot of history and wins behind it.
— Levi Olsen
National Sales and Marketing Manager
Hutchinson Tire North America

Q.Lennard,
Why not just abandon trying to find good nomenclature for ‘effective top tube length’ and just stick with the terms “stack” and “reach” – I’m pretty sure you’ve used them previously, and companies like Trek and Cervelo explicitly use them.

Whether a consumer uses your “effective top tube length” or “Reach” is irrelevant as both concepts allow you to accurately compare different frames’ sizing.
— Jordan

Q.Dear Lennard,
I had been calling the TT fit “functional top tube length” until I found this article on Slowtwitch.

Many companies, including Salsa, Specialized, Planet X, On-One and Turner, have been including the reach and stack in their geometry charts.
— Shiggy

I love this! This is what I had intended in the first place — namely for people, in understanding the limitations of seat tube and top tube length dimensions for frame sizing, to embrace stack and reach. When a reader didn’t understand how to use it, the whole discussion became mired in the morass about top tube length and how it relates to the seat angle – exactly what stack and reach avoids. When both illustrations I had made to elucidate it and a deleted paragraph were added back in, the flood of emails not understanding it finally ceased. The posting had glitches and didn’t appear correctly until Friday of last week, so check it out if you only saw it early in the week.

I’m very pleased to see others suggesting getting out of the morass by using stack and reach!
— Lennard

The steeper 74 ST angle moves the BB rearward relative to the 72 ST position, and, to maintain the saddle-BB distance, requires moving the saddle rearward. The rearward movement of the BB and the saddle will produce an INCREASE in the distance from the saddle to the bar.

So the rider would notice that the reach to the bar is greater, as would be the case with the 72 ST and a longer TT.

Q.Dear Lennard,
Thanks for that very interesting piece. I use a device called ‘FitStik,’ which has many of the same ideas, but includes reach, stack saddle, saddle height and saddle angle into one. I can adjust any bike in 2 minutes. It was so simple that I cannot imagine life without mine. Whatever happened to it?
— Geoffrey

A.
Dear Geoffrey,
I have a FitStik myself and love it. Check out the videos on how to use it. I haven’t heard from the company in 10 years or so. I’m not sure what happened after the company’s 2002 move to Portland, but I know as early as 2005 people were telling me that it is no longer available. I’m assuming that’s the case, but I don’t know. Anybody know?
— Lennard

Q.Dear Lennard,
I was hoping for your opinion on cyclocross v-brakes, specifically short-pull vs. long-pull options.

I currently have a single-speed ‘cross bike set up as a commuter, and wanted to upgrade to v-brakes (I’m a big man, and could use the extra stopping power). As it’s a commuter, mud clearance is not a primary concern. My options are:

Upgrade to Cane Creek long pull/v-brake levers, and use a traditional mountain bike v-brake (of which I have spares)
Upgrade to the MRP CX9 “short pull” cyclocross v-brakes, use my existing road brake levers

Given your recent article, I see you’ve spent time on both setups. Which did you like best? The cost difference here (new levers vs. new calipers) wouldn’t be a big issue for me, as I’m really just looking for the best setup.
— Sean

A.Dear Sean,
In my experience, it will make little difference either way, except that the second option will be lighter and a bit grabbier and more powerful.
— Lennard

Q.Dear Lennard,
I am planning on building a Shimano Di2 bike. I have been told that 7800 brakes won’t work effectively because there is a different pull ratio. Will braking performance be significantly compromised if 7900 brakes are not used? What about other manufacturer’s brakes?
— Mike

A. Dear Mike,
Indeed, Di2 and Dura-Ace 7900 brake levers have reduced leverage and increased cable pull by virtue of having the cable hook further from the pivot; they are matched to a higher-leverage 7900 brake. So you’d have weaker braking with those levers and 7800 brakes.

Prior to the advent of Dura-Ace 7900, Campagnolo, Shimano, and SRAM all had similar road-lever cable pull, so swapping in brakes from Campy or SRAM will not make a significant difference. Some aftermarket brakes, like from The Hive (there was a recent recall on these, but I believe all is now well with them), have specific adaptations for 7900 (and Di2) levers. The Hive brakes have an interchangeable link to vary the leverage. The eeBrake is also supposed to work with both, and I have been riding those with 7900 levers for over a year and am quite happy with the performance.
— Lennard

Q.Dear Lennard,
I like your efforts to impose the stack and reach measurements for bicycle frames, but can you also apply these kinds of measurements to helmets and shoes? It would take the guesswork out of shopping for round or oval shaped helmets if we just had cross-section measurements. The same goes for shoes. If we could only get a longest point and widest point measurement (and the point on the length where that occurs) then we could more accurately size our feet for each manufacturer. Why don’t companies do things like this? Is it all in support of forcing you to the dealers where you can try things on?

A.Dear Michael,
I have no idea why that is, but yours is a good idea. That tool they used to put your foot in when you’d go buy shoes certainly is capable of providing the numbers; the question is whether the shoe companies would publish sizing based on those numbers. It could happen, though. For instance, when alpine ski bindings appeared in which the toe and heel were mounted to a plate rather than were screwed straight into the ski, boot sizing adapted. The binding plate allowed the toe and heel to moved fore-aft on the ski to fit different boot shells, and the boot manufacturers started engraving the shell size on the boot, which could be different from brand to brand for the same shoe size. It made binding adjustment a snap, and it just made sense.

Given that purchasing of all consumer goods is inexorably moving more toward online and away from brick and mortar, the need for more universal sizing parameters exists. So I hold out hope that change can come in bike sizing as well as sizing of other items like shoes and helmets.
— Lennard

Q.Dear Lennard,
Regarding the reader (Dan) that asked the question regarding his broken Campagnolo shifter.

He could indeed mate Shimano shifters with Campagnolo cassettes by using products from JTek.
— Chris

A.Dear Chris,
That’s true, and JTek is back up and running now after the unfortunate death of the founder due to cancer. His son is doing a great job and is getting parts back in stock.
— Lennard