Technical FAQ: Cranks, bottom brackets, and big helmets

This week, Lennard Zinn answers multiple questions about cranks, bottom brackets, and oversized helmets

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Changing an old Campy compact crank

Dear Lennard,
I have been looking to change my full size Campagnolo crankset to a compact crank, but I am getting confused with what parts are available.

My gruppo is full Campy Record 10, circa 2003. This pairs a full sized Record crankset to a square taper bottom bracket/spindle. I have searched for a square taper compact crankset to swap to but can’t find one. This is where the confusion begins.

Are there any other cranksets that I can swap into my existing gruppo? If not, how many different components am I going to have to change? What type of bottom bracket will be compatible with my frame? What kind of crankset will work with my front derailleur? Will alternative cranks like Rotor Q rings work?
— Bob

Dear Bob,
At the beginning of the Age of Compact Cranks (which we’re still in), Campy made a square-taper compact (i.e., 110mm bolt circle diameter) crankset. In fact, my wife still has a carbon Campagnolo Record CT crank on her lugged steel road bike I built a zillion years ago for her. And we (Zinn Cycles) still offer custom compact square-taper cranks in any length, from 100mm to 250mm. That said, they require a different spindle length than yours probably is as well as a Shimano taper to the spindle, not a Campagnolo taper.

Otherwise, you can upgrade to a modern compact crank; you simply need to get a compact crankset with a bottom bracket threaded the same as your bike (it’s either BSA or Italian thread, I imagine). It wouldn’t hurt to upgrade your 10-year-old bottom bracket anyway. There are plenty of those available from Campagnolo, Shimano, SRAM, and FSA, among others. Your other parts can stay the same. And yes, you can run Rotor chainrings on them.
― Lennard

Loctite necessary to fix bearing movement?

Dear Lennard,
I have a 2012 Trek Madone 6.9 SSL 58-inch H1 frame fitted with a Campagnolo Record 11S gruppo.

The fitting for the left bearing seems out of [whack]. My technician states that Trek has a problem with Campy cranksets and that other cranksets fit “properly,” and that the solution (which is available in the Trek manual) is to [use] Loctite [on] the bearing to eliminate the movement of the bearing. We are talking small but noticeable movement.

The technician states that if he Loctites it, the possibility is that the frame gets damaged or that the bearing cannot be removed. The Trek manual is from 2010, but Trek is not really answering this question.

I love my campy and my Trek; what to do, and how?
— Michel

From Campagnolo:

It seems that this gentleman’s shop is not following the Trek instructions. The Trek BB shell works perfectly with Campagnolo Ultra Torque. There is no need to Loctite the bearing into the frame. Trek uses a two-part sleeve retainer to loctite two spacers into the shell, then they also supply the spacers with several shims to adjust the tolerance of the system. We have built many Treks with this system and have not had any problems.
Daniel Large

North America Technical Service
Campagnolo North America Inc.

From Trek:

We build hundreds of Project One Domane’s, Madone’s and Speed Concept’s with Campagnolo drivetrains every year without issue.

Our service instructions detail the installation process of Campagnolo Ultra Torque cranks to our BB90 format frames (when opened, skip ahead to Page 18). This also notes the specific Loctite required for proper installation.

To further assist, listed below are Trek’s part numbers for the Trek/Campy BB90 kit and Loctite; each can be ordered through any authorized Trek retailer.

Campy BB90 kit: P/N 407383
Loctite 638 (10 ml): P/N 408082
Loctite 7649 Primer: P/N 408083

Eric Maves
Trek Bicycle
Project One Guru

Longer cranks for long climbs

Dear Lennard,
I am 6-foot-4 and weigh 200 pounds, and have a 36-inch inseam. I currently ride a 21.5-sized frame Trek full suspension mountain bike. I have been riding 175mm cranks the entire time, but feel as if sometimes I don’t have enough leverage to push up those really long climbs. I was wondering what your thoughts are on a longer crank, say 180mm? Do you think that extra 5mm will [make] a significant difference? Will I even notice it?
— Brian

Dear Brian,
Yes, I’m confident that you will feel a difference on long climbs. Whether it is significant will be for you to decide. Back in 1979 when I switched from 177.5mm to 180mm cranks, I was amazed at the difference 2.5mm made. I was suddenly dropping guys on the climbs that always had kept up with me before. As with anything, there is a psychological part too; I believed I would be faster and when I was, it gave me more confidence.

The closest hard road climb to me here in Boulder is Flagstaff Mountain (“Superflag”), and I’ve done decades of crank-length testing there, mostly on myself, but sometimes with other riders as well. I have a 38-inch inseam and ride 205mm cranks on my road and cyclocross bikes, because I find that, over years of testing, that I’m consistently two minutes faster over this 30-ish-minute climb on that length than on 180mm. Other riders of my height who tested with me also were faster with each increasing length from 180mm to 205mm.

That doesn’t guarantee you’ll be faster. Some people are natural spinners and could produce great power on a short crank, and others are gear mashers who tend to benefit from the greater leverage of a longer crank. You won’t know until you try it. And you want to make sure that the extra 5mm doesn’t result in frequent pedal strikes as well. If you already hit your pedals frequently, I wouldn’t recommend the switch.
― Lennard

Oversized helmets

Dear Lennard,
Just saw your piece on XL helmets and wanted you to know that Giro does make several models with their Universal XL fit that fit up to a 65cm head. The Venti comes in the Universal XL, which fits 58-65, Xar and Savant come in S, M, L, and XL, with XL fitting 61-65cm.
— Peter Nicholson and Mark Riedy
True Communications (represents Giro)

Dear Lennard,
In response to Brendan’s question about big helmets, I thought I’d share a few that have worked for me. I also have a 7 3/4-sized head and while there are plenty of helmets that claim a maximum diameter of 62cm (the right metric for that hat size), I find most of them are too round and get pinched at the forehead. Having recently crashed out of my Bell Volt, I went on a shopping trip to find a replacement. Bontrager, Bell, and Specialized all offer a truly big “L.” Bontrager maxes out at 64cm, Bell at 62, and Specialized at 63. Lazer has recently introduced an XL/XXL size of their O2, which is a 61-64cm size. I’m presently riding a Bontrager Oracle with a Specialized Echelon II as a backup/around town helmet. There are some options around for the pumpkin-headed cyclist!
— Peter

Dear Lennard,
Like Brandon, I wear a 7-3/4 hat (at least in a sized New Era baseball cap). Before my present helmet, I have always gone straight to the largest size available. When trying out the Giro Aeon last summer, I was delighted to find out that I could fit into the medium — I can even fit a skullcap underneath for cold rides. The large adjusted to fit me just fine also, but I went with the medium to save grams (while not a weight weenie in general, on the head I find it desirable to reduce mass). I am wondering, though, what the experts might have to say about protection; for example, the medium is of course smaller on my head, and perhaps I am more exposed in some crash scenarios. If you find this interesting, perhaps you could pass this question along to industry folks — for someone who overlaps sizes, should they go up or down from a safety perspective?
— Paul

Answer from Giro agent:

All that I can really say is that each size in all of our helmets passes the designated safety standards.

We don’t promote one helmet as being safer than another.
Mark Riedy
True Communications

Dear Lennard,
In regards to big helmets, I consider myself a bit of a connoisseur. I wear a size 8 fitted hat and have trouble finding helmets that are not only big enough at the band, but deep enough so that they come down far enough on my head. Luckily, the options are not as bad as one might think. The only brand I know of that doesn’t make anything to fit me is Giro. Some great options are the Bell Volt, Lazer Helium, and the Specialized Prevail. All three of these are big enough to fit my head with room left, so they should be good for anyone that can wear a fitted baseball cap.
— Matt

Dear all,
Here’s a hat sizing chart.
― Lennard

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