Dear Lennard,
I am 6' 6", 200lbs with a 36" inseam. I currently ride a 2003 Tourmalet size 61 steel frame and was looking to upgrade to a livelier ride with an aluminum frame. I am trying to get the most out of a stock bike that costs under $1300.

I talked to the shop about putting on an Alpha Q fork and using the longest stock cranks arms I can find (180mm Rival Compact cranks only 5mm longer than the 175mm Bontrager cranks the bike comes with). (Even if I could afford to the correct crank length you recommend, I would need a custom frame with raised bottom bracket.)

First, the shop told me the longer and beefier steerer tube of the Alpha Q fork won't work (or at least won't give me any more headset height, I know there are limits to the stack height, but I found the Cane Creek Solos can be stacked to 38.8mm not much but better than the 27mm stack I have now).

Now, the shop is telling me that longer cranks would be too hard to push. Does this make sense? They are only 5mm longer and would allow me to drop my seat height and move my seat forward. Or does this sound more like a shop has no expertise or real knowledge about fitting stock frames to tall riders?
-Ben

Dear Ben,
Neither comment makes sense, but both are typical of the lack of understanding in general in the bike industry and among shop employees about the issues facing tall (and short) cyclists.

Harder to push? If you want to pull a stuck nail out of a board, which will be harder on you – pulling it with a claw hammer or with a long crowbar with a nail claw on it?

From long experience with myself and with hundreds of customers over more than a quarter century, I know that you will find those 180s to be a revelation - it was for me back when I was on national team under Eddie B.'s tutelage (he wanted me to use considerably longer, but I could not find any longer ones at that time). And longer yet than 180mm will benefit you yet more. Your legs are certainly long enough to get over that pedal on the 180mm cranks – your knee and hip angles will still be less acute than the majority of cyclists out there, since those cranks as a proportion of your leg length will be lower (around 19.7 percent, vs. 22 percent and far more on short riders on 170mm cranks) and the extension and contraction of your muscles will be relatively lower as well.
I'm your height and ride 207.5mm and would not go back – they are 21.6 percent of my inseam length. And as you know, I am constantly testing and reviewing cranks of all different lengths, so I constantly am re-checking my experience on 207.5mm, 205mm and 200mm (on both road bikes and mountain bikes) vs. the 175mm and 177.5mm cranks I usually am sent with groups for review.
According to True Temper, you can cut an Alpha Q Z-Pro fork steerer to 144mm longer than your head tube (I've included the 14mm for the bottom headset cup: 130 + 14 = 144). Here's what Bert Hull from Alpha Q has to say:

“Spacer stack height limit on the Z-pro is 130mm from frame to top of stem. With standard stems and headsets, that works out to about 90mm of spacers, which is quite a lot. There is no magic to this number, but we need to set a limit somewhere. The issue is not so much safety as it is stiffness. The steerer is not going to break because you put extra spacers above the upper bearing. As you know, the deflection of a cantilevered beam increases exponentially with distance. Adding spacers quickly adds up to a less stiff cockpit. We set recommendations on spacer stack height so that people who use our products will enjoy the performance we design them for.

Sometimes people ignore our guidelines to customize their ride, and if they can live with the compromise of performance in order to get their position more comfortable, then for them it is a situation they can live with.

As for the question about bearings not working with tall stack heights, I don't see why there would be a problem with going higher. Perhaps that bike shop owner could enlighten us all with his logic on that one.

I could run a special test if you like.

I can set up a 100000 cycle CEN test on a handlebar mounted on a stem above a ton of spacers and see if the bearings give out before the test is complete. I will take a week or so to run it.”
-Bert Hull, Product Manager, Alpha Q Components

I would do those upgrades. You won't regret it.
-Lennard


Dear Lennard,
Several photos on the cycling news website taken at RVV: http://www.cyclingnews.com/road/2008/apr08/rvv08/tech.php?id=/photos/200...
Show SRAM sponsored Astana bikes with Shimano DA cranks installed at RVV. Seeing that both bikes on top of the team car and propped up against the bus (ready to race that day) have DA cranks installed suggests that it isn't just one rider. Do you know what's going on?
-Fred

Dear Fred,
I don’t know why, but I will gladly guess while awaiting the response from SRAM. Given that clearly some of the bikes propped against each other and on the roof do have SRAM cranks, I would guess that it has to do with crank length rather than SRAM crank shortages. The bike in the photos is a tall bike (Tomas Vaitkus is 6’1”), and I would not be surprised if it equipped with 180mm cranks, which is available in Dura-Ace but is not available in SRAM Red – those only go up to 177.5mm.
-Lennard

Dear Lennard,
I've recently ordered a Crank Brothers Cobalt SL DirectSet and am wondering what changes, if noticeable, it will make to my steering. I'm on an '06 Madone, size 58, with a Cane Creek S8 at the moment.

Am I correct in assuming that a shorter lower stack height will effectively steepen my head tube? Is it possible that the ~7mm net change will make my bike “too steep” up front?
-Chris

Dear Chris,
Yes, it will steepen your head angle, but I doubt you will notice the difference. The distance from the rear tire contact patch to the bottom of your head tube is on the order of a meter, or 1,000mm. So the sine of the change in angle will be around 7/1,000 or 0.007. The angle change is thus about 0.4 degrees. It will make the steering quicker, but probably not a noticeable amount.
-Lennard


Dear Lennard,
I recently acquired a TT bike from a club mate with full Dura-Ace 10 speed. My road bike is a combination of Shimano Ultegra derailleurs with Shimano 105 shifter/levers running a 9 speed cassette. I cannot use the Dura-Ace bar end shifters on the road bike. Will the 105 shifters work with the Dura-Ace 10 speed or do I need to buy either an Ultegra or Dura-Ace shifter/levers to make the switch?
-Scott

Dear Scott,
You cannot use those levers with your 10-speed drivetrain. You would need to get Shimano 10-speed STI shifters – they could be Ultegra or Dura-Ace, and they could also be 105, but they must be 10-speed, not 9-speed.
-Lennard

Technical writer Lennard Zinn is a frame builder (zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including Zinn and the Art of Triathlon Bikes and the pair of successful maintenance guides Zinn and the Art of Mountain Bike Maintenance – now available also on DVD, and Zinn and the Art of Road Bike Maintenance, as well as Zinn's Maintenance Tips and Skill Building for Cyclists.

Zinn's regular column is devoted to addressing readers' technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions DIRECTLY TO ZINN. Zinn's column appears here each Thursday.