Technical FAQ: Shifting troubleshooting, CX worlds flats follow-up

Lennard Zinn addresses questions about shifting, compatibility, and brakes, and includes more about the myriad flats at cyclocross worlds.

Solving a shifting problem

Dear Lennard,
I use Ultegra 6700 on my cyclocross bike as a commuter bike. The right shifter seemed to try to pull the cable when shifting to larger cogs, yet it would fail to fully catch the cable. I found if I put the lever forward slightly while pushing it to the left to shift to the larger cog that usually works, but now shifting in the other direction is a similar problem.

I use TRP CX9 brakes.

1. Is it worth buying just the right Ultegra 6700 shifter?

2. Would 6800 “brifters” work with existing derailleurs? If not, would it work with the TRP brakes? Or would I need the newer 8.4 brakes?
— Michael

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Dear Michael,
Sure, you can buy just a right Ultegra 6700 lever. But your problem sounds to me like a sticky lever. I’ll bet that if you squirt WD-40 into that lever repeatedly from the top and bottom, it will both free it up and make it engage better. If that works, then follow it up by squirting in some oil without solvent to gain some durability; Pedro’s Syn Lube, motor oil, etc. should displace enough of the WD-40 hold up for a while.

A 6800 (11-speed) lever would not work with your derailleur. When Shimano went from 10-speed to 11-speed with road groups, it changed the shift actuation ratio on the rear derailleur from 1.7 to 1.4. Otherwise, all indexed Shimano rear derailleurs (other than 7-speed and 8-speed Dura-Ace) from 6-speed through 10-speed road and 9-speed mountain had had a 1.7 shift activation ratio. [This differs from the answer I originally posted that ran Tuesday and Wednesday, even though I have all of this information written down in table 5.2 on page 116 of the “5th edition of Zinn and the Art of Road Bike Maintenance.”]

And as for braking, the 6800 levers would work the same as the 6700 ones did with those TRP CX9 V-brakes.
― Lennard

Compatibility between cassettes and shifters

Dear Lennard,
I’m guessing you’ve answered this one before, although I haven’t found the exact answer while searching so pardon any redundancy. 

I have a CX bike with Ultegra 10-speed shifters/derailleurs and an 11-28 cassette. 

I want to make it a better climber with at least a 32 cassette, but ideally a 34 or 36. I’ve seen chatter that some SRAM cassettes with 34 or 36 can work, if I use it in conjunction with an older XT 9-speed/long cage derailleur. Is that true? If not, is the best option a 32 Ultegra cassette with an Ultegra 10-speed, medium-cage derailleur? I’m hoping I don’t have to scrap my existing shifters. I’m running FSA SLK cranks with 46 and 36 rings.
— Neil

Dear Neil,
Yes, a Shimano 10-speed road shifter will work with a 9-speed Shimano mountain-bike rear derailleur. Your second option also will work.
― Lennard

Swapping brakes?

Dear Lennard,
Have you read any research indicating that having a left brake that’s connected to the rear wheel may help avoid a type of endo accident?

Recently, I spent three weeks in a hospital in Siena because I rode into a very deep pothole; the last thing I remember was braking with my left hand. My working notion is that had the left brake been the rear brake, perhaps I would have suffered less damage.

Dear Greg,
I know of no such research, and it obviously depends on how hard you pull with the hand that’s hooked to the front brake. Motorcycle riders and European cyclists tend to have a left-hand rear brake, and I don’t know the reasons other than tradition. If it’s not your dominant hand, perhaps you won’t pull as hard. Or vice versa. Hard to say. And, of course, if you switch it around and are not used to it, you could easily get confused in an emergency-stop situation and pull the wrong brake lever. I did that on my second mountain-bike ride ever, on Tom Ritchey’s personal bike when I had just started working for him in 1981. His bike was set up moto-style and, while I knew that consciously, when I got out of control down a steep, bumpy dropoff, I couldn’t remember which was which when it really counted; I pulled the wrong lever, went flying over the bar, knocked the wind out of myself, and barely managed to roll over on my back and kick the bike with my feet to pop it over me and prevent it from slamming into me.

There are definitely some instances where you can avoid endos by having a left-hand rear brake by the very nature of the cycling event, but those don’t tend to be catastrophic crashes when they do happen because they’re at low speed. I’m talking about entering a triathlon cycling-to-run transition zone and approaching a barrier in cyclocross. In either case, the rider is approaching with the right leg swung off of the bike and dangling to the left of the bike while the rider supports his or her weight primarily on the left pedal and left side of the handlebar. If the rider then brakes with a left-hand front brake, the bike will endo easily, as it has so little weight on the rear wheel. In that situation, where the rider is suspended on the left side of the bike, the right hand is so unweighted that it can’t really pull the lever hard, so if the right hand were instead controlling the front brake, the tendency for the bike to endo would be reduced.

To prevent going over the bars from grabbing too much front brake, a much more foolproof thing to do is to spend the 20 bucks for an Ultra Cycle Brake Safe and put it on your front brake cable. You don’t want this accident again, and you will probably always otherwise be wondering if you might over-brake unconsciously if the same situation were to arise again. This thing really works.
― Lennard

Follow-up on bike geometry and bike stability

Dear Lennard,
Fantastic Rake and Trail etc. write up. It may be worth mentioning that as we all start running wider tires on our existing bikes, the wider tires are also a bit taller, which changes the radius of the wheel. We all marvel at how much more solid the bike feels cornering with more rubber in contact with the road, but we also may be sensing a bit of slacker geometry that could be perceived as increased stability as well.
— Davo

Follow-up on cyclocross worlds flats

From Stephen Hyde’s mechanic:

Stephen Hyde rode the course for a pre-ride on Sunday after the U23 race. The conditions were changing rapidly. Temps went up, slight rain, even a spot of sun for a minute or two. All the small stones (3/4 inch to 2 inches in size) that had been frozen in the ground were coming to the surface. The worst sections were some of the “drop ins.” The stones came loose as a result of braking and the thaw. The thing that made it worse was that they all rolled to the bottom of the drop. To top that off, they were hidden in the puddles at the bottom. So the rider drops in and compresses at the bottom on a pile of sharp, small stones. That’s my understanding of it. Perhaps with a bit more pressure some of that would be lessened, but tires were also just getting cut. Pressure doesn’t always alleviate that.
— Stu Thorne, Cyclocrossworld, Inc.

From François Marie, maker of FMB (François Marie Boyaux) tubulars:

It is a circuit that is entirely made, not a natural ground. I think that the ground is made of construction materials (rubble) and then covered with a thin layer of earth. After the thaw the ground became very muddy, the tires rolled below the layer of soil, directly on the rubble. Punctures are caused by cuts with sharp rubble, and punctures are caused by pinching on non-visible rubble.

The riders could not see under the mud, so it was not possible to lighten the bike by passing on the stones. There has never been a race on this terrain. With this experience, it was possible to envisage tires better adapted to these conditions to avoid cuts. Admittedly a few grams complementary, but decreasing the risks of puncture while rolling with a pressure not too low.

I would like to say a few words about the choice of tires in Luxembourg.

The majority of our riders used the Super Mud; Ellen Noble used The Super Mud in PRO version. The choice was correct to obtain a very low pressure without taking risk of pinching. On this model we have very wide folds and make a damping to decrease the pinch with the rim with the low pressures.

We have a Sprint 2 profile that is excellent (especially at the front) for frozen terrain. This profile grips in traction on the snow and the ice and during taking the angle on the side or in turn the high buttons of the sides provide a good security. This profile is not used enough by riders who have too much reflex to use tires for mud when the terrain slips.
— François Marie, FMB

From Dugast tubulars:

The cause was mainly sharp stones and probably also pieces of metal that cut the tubulars — these were most flats and happened on a part of like 100 meters on the course. Of course, there were other flats as well, like snakebites or stones on other places. But most flats happened in one particular part of the course. Most tubulars had a cut in the sidewall or in the tread.

Then there was the temperature that was increasing, so that the upper layer on the track was gone by the end of the U23 race on Sunday morning. Usually when you have a course with a lot of stones, you see flats in the first laps (that usually happens at the Namur World Cup) and while riding, the riders turn the stones or push the stones again deeper in the ground. But in Luxembourg, the ground was still frozen, except for the upper layer.
—Tamara Willems, A. Dugast BV

From Challenge tubulars:

The winners of the race were rightly Wout Van Aert, his father, who works for him in the pit, and his coach, Niels Albert. They could see that pinch flats and cuts were going to be an issue when the course got muddy and sharp rocks came up from the fill dirt out of which the course had been built. So they dusted off those tires made out of Dugast casings with green Michelin Mud tread glued on. They’re heavier, but they have more puncture resistance. And they upped the pressure in the tires after Van Aert got a puncture himself.
— Morgan Nicol, Challenge Handmade Tires