Technical Q&A with Lennard Zinn – Questions of standards and compatibility

Dear Lennard,I'm confused about the BB30 design. How do they increase the spindle diameter from 24mm to 30mm and put the same sized bearings inside the BB shell? Is a larger diameter BB shell the design change the article mentions?James Dear James, Yes, the bottom bracket shell is larger. Here are specs: Lennard Dear Lennard,

By Lennard Zinn

Just what does the new BB30 standard change?

Just what does the new BB30 standard change?


Dear Lennard,
I’m confused about the BB30 design. How do they increase the spindle diameter from 24mm to 30mm and put the same sized bearings inside the BB shell? Is a larger diameter BB shell the design change the article mentions?

Dear James,
Yes, the bottom bracket shell is larger. Here are specs:

Dear Lennard,
As I enter the “O.F.” age of cycling, also known as “I.M.P.” (Intermittent Methane Propulsion), I’m finding that the 12-27 Ultegra cassette is a bit much. I have aching knees the day after hard climbing. I’d like to change to an XT/XTR 12-34. Before I do that, I have a few ignorant questions:

1) Can I use my Ultegra 9-speed front brake/shifter?

2) I know I need a new long-cage thingy with the little wheels, but do I need the XT/XTR derai???… (you know, that French-named thingy that shifts back there)?

3) I only have 1000 miles on the cable, should I change it also?

By the way, this might make an interesting addition to your Zinn
and the Art of Road Bike Maintenance
book, which is my first line of defense when strange noises start or pieces fall off.

Dear Tom,
Well, first of all, I’m taking a leap of faith that your Ultegra setup is 9-speed. If it is, then you can indeed use your current Ultegra STI levers with an MTB cogset on there.

While you do need a new French-named thingy, you don’t necessarily have to get an XT/XTR, although you could use one of those with good results. Instead, you could just get a 9-speed Ultegra triple rear derailleur, and it would work fine.

As for the cable, no you probably don’t need to replace it, but if the end has frayed where it was clamped to the point that there are broken strands, you will wish you had replaced it; it will be such a PITA to deal with. If I were you, I’d just get a new cable when you buy your new French-named thingy.

Dear Lennard,
I’m currently running 9-speed Dura-Ace and have no desire to upgrade. I folded up my front wheel a few months back and was looking at the 7801 SL as a possible replacement, upgrade of my wheelset, but I’ve read that it is 10-speed only, not compatible with 9-speed cassettes, is there any way to make it work? I know that the new 7850 SL is advertised as 9-speed compatible, what gives?

The other question I have regards weight limits. I typically run between 220 and 230lbs. In looking at American Classic Wheels, I did find a weight limit chart, and for just about any of their wheels, I’m at the upper end.

Dear Adam,

No, the 7801 can’t be switched to a 9-speed body, so if you want tubeless wheels, you can hold out for the 7850, which will be out in spring. I just watched them being built in Malaysia in December.

I’ve ridden the American Classic Hurricane for years in cyclocross, etc., and they have never even needed truing. I weigh 175-180.

American Classic also has the Victory, which is also rated for heavier riders.

Dear Lennard,
I ride a 57cm LeMond Zurich (all steel) with a nine-speed all-Ultegra drive train. My problem is with the front derailleur. I find that the derailleur cage has a “halfway” position when shifting from small to large front rings allowing me to use the inner 39t ring with the 13t and 14t cogs in back. But, once the chain is on the big front ring (53t), I can’t find the half way position allowing me to use the 23t in the back without chain rub. My cogset is 13-25. Is there something wrong with my derailleur?

Dear Robert,
I bet that you have too much cable tension. If you back off a hair on your left barrel adjuster, I’ll bet you can get it to work. With too much cable tension, when you shift up and jam it up against the limit screw, it won’t allow the shifter to move beyond its little internal stop to be able to operate the trim function. You may also need to back out the outer limit screw slightly, if you get chain rub on the 53X13 combo due to the lower cable tension.

Dear Lennard,
Whenever I hear talk about crankset Q-factor, it almost always concerns smaller widths being better. I ride both road and mountain bikes, and for me, the MTB with wider cranks feels more comfortable and causes less knee pain. My octalink MTB cranks also seem to have more “heel clearance” (what I am calling the distance from some standardized point on the pedal to the outer edge of the spindle end of the crankarm). Both of these factors help me because I have a large forefoot varus and I am significantly duck-footed.

Specialized Body Geometry shoes and shims or homemade forefoot shims deal well with the forefoot varus, but I would like to know what is the best way to increase the heel clearance and possibly the Q-factor on my road bike. I currently have Shimano 9-speed components on my bike. I have found little information on crankset dimensions, and my own pedal center-to-crank measurements have shown nearly identical dimensions for all of the popular systems.

I have thought of using triple cranksets (road or MTB with larger rings), a BB for a triple with my double (obvious chain line issue), adding or bonding and tapping a washer between pedal and crank, and re-drilling my shoes. What do you think is the best solution and how can I do it?

Dear Michael,
You should check out Knee Savers, which are threaded inserts that screw into the crank and accept the pedal threads, thereby spacing the pedals out another centimeter or so on either side.

Dear Lennard,
I recently bought a new frame to replace my old ’83 steel Trek. I have 9-speed Shimano components on the old bike and was moving the parts over last night to the new frame. However, the old front derailleur was 28.6mm and the new seat tube is 31.6. Can I use a new 10-speed front derailleur with the 9-speed drivetrain and shifters? It is pretty hard to find new 9-speed parts anymore and I can’t afford to upgrade the entire thing to 10-speed at the moment.

Dear Paul,
Yes, you can use a 10-speed front derailleur with a 9-speed system.