Losing my grip
Dear Lennard,
I am having a problem with the removal of the drive-side bottom bracketcup. It is a Shimano UN 72 and it has been removed so many times that thesplines are now gone. The bottom bracket itself works fine and I can leaveit in, but eventually it will need to be replaced.

The splines are so rounded off that when pressure is applied in an attemptto remove the cup, the bottom bracket tool spins and further chews up thesplines. I am turning the tool clockwise for removal.
Jeff

Dear Jeff,
The first thing to try would be to get your hands on a Tacx BB cupremover, since it screws into the end of the axle and puts a lot more inwardpressure to stay in the splines than you can. And, as you probably know,the drive side is only left-hand threaded (for clockwise removal as youhave been attempting) on English-threaded bikes. If you have an Italianbike (36mm X 24threads-per-inch), you have to turn it counterclockwise.

If the Tacx tool does not work, someone with a higher end bottom bracketthan a UN72 but with the same problem could, with some reluctance, takea big hammer and smack on the drive-side end of the BB spindle, assumingit is the type with two separate cups, rather than the less expensive typein which the drive-side cup is integral with the cartridge. This will breakthe bond holding the cartridge into the cup. This won’t work with yourbottom bracket, though, because the drive side cup and the BB cartridge are onesolid piece of steel.

Once the cartridge is out, you grind through the cup along a line to create a split in it so that you can fold it inward and remove it. I have done this before (with a steel cup even) and I managed not to damage many of the threads in the BB shell, so it can be done. I used an air-powered die grinder with a flame-shaped carbide bit. It will be much easier if you have an aluminum cup. You may be able to just use a hacksaw in that case.
Lennard

Gimme a brake!
Dear Lennard,
I've been happy with the performance of my Shimano 7800 caliper brakesover the season. Now the time has come to replace the pads and I wonderwhether I succumbed to a Shimano-engineered “placebo effect.”

According to information I have obtained from various retailers there is no distinctionbetween 7700 and 7800 brake pads (only one part number). Does this meanthe 7800s (also called the 10-speed system brakes) are really no differentthan the 9-speed pad technology? If so, has Shimano misled consumers? Iwould think so, since the marketing copy used to sell the 7800 brakes emphasizesthe improved performance of the new pads:

"Increased rigidity, tighter tolerances and the striking reductionin flex are a big part of the BR-7800 story, but the new multi-conditionbrake pad compound has also made race-winning advancements. In developmentfor over a year, the new pads are more powerful and durable in dry conditions,with outstanding durability in the wet as well. The powerful braking andendurance in the wet, with no compromise to the power and durability youneed in the dry, has been recognized as a significant racing advantage."

I really thought I felt the new pads were better. Now I'm not so sure andam starting to hate Shimano. Maybe Shimano has an inventory of 7700 padsto get rid of? I am frustrated that I cannot get a straight answer on thismatter.
John

Dear John,
I was curious, so I ordered a couple sets of both the 7700 pads andthe 7800 pads directly from Shimano, and they arrived yesterday. They aredefinitely different. The packaging is different, the 7700 pads are blackerand shinier than the slightly grayish 7800 pads, and the numbers on theback are different. The 7700 pads say R55C on the back. I cannot read thenumber molded into the 7800 pads, but it clearly ends in a “2” and notin a “C”. Perhaps the retailers you dealt with were buying old stock fromdistributors who had not yet restocked with 7800 pads.

The pad shape is the same and are interchangeable into each other’spad holders. Anyway, here is what Shimano says about it:

Dear Lennard,
Our Dura-Ace 7800 brakes have an improved pad made with the R55C2 compoundthat has improved resistance to wear in wet conditions. The Dura-Ace 7700brakes utilized pads made with the R55C compound that had a much shorterservice life than the R55C2 when used in wet conditions.Here are the corresponding part #’s;
R55C2 (BR-7800) replacement pads- Y8A098020
R55C (BR-7700) replacement pads- Y8FA98020Jason W. Leith
Bicycle Components Division
SHIMANO AMERICAN CORPORATION

Big guys on bikes
Dear Lennard,
As the specialist in bicycles for tall people, I wonder if you have any thoughts about how to tame an unruly front end on a 64cm frame?

I am 6 foot 4 and ride a Colnago Master Olympic with a straight steel fork, an ITM Goccia quill. The quill diameter is 22.2mm, length is 120mm with 76 deg rise. When climbing, I like to sit up and ride with my hands on the tops of the bars. When I do, the front end gets squirrelly, as if the bike wants to pull a wheelie. No problems when I am riding on the hooks or in the drops.

I've tried riding with my hands spread wide apart, but the front end still feels "light." What can I do to address this problem?
David

Dear David,
Tall bikes under tall riders have a tendency to feel light on the front end, especially if the top tube is too short. It is a weight distribution problem, and I can explain why it happens more to taller riders. In general, road frames from a given company tend to have the same chainstay length for all sizes of a given model. Furthermore, the seat tube on the bigger frames is not only longer, but it is usually also tilted back at a shallower angle.

This means that your butt is higher and further back over the rear wheel,effectively placing your center of gravity further back relative to thewheels than a shorter rider. Combine this with insufficient reach to thebars for the taller rider relative to the shorter one, and you have a bikethat will pull wheelies when you climb holding onto the bar tops.

With this bike, I suggest deeply bending your elbows and lowering yourchest when climbing to put more weight on the bars. It's not ideal to beforced to do this, but you actually will work your glutes more as a benefit.

You might also try the free frame fit calculator on my Web site: www.zinncycles.com,to see if you have a relatively short top tube and stem, in which caseyou could increase your stem length and help it a bit.

Lowering your stem will also help, but that may not be ideal, sincetall riders on stock frames generally have relatively more drop to thebars from the saddle than shorter riders.
Lennard

Cleat position and leg length
Dear Lennard,
I had a few questions about cleat placement relative to somethings I read in your CyclingPrimer. You wrote that for people who have an upper leg length differencethat the cleats should be adjusted fore (short leg) and aft (long leg).I'm told my right leg is about 1/8-inch shorter than the left. I'm notsure if the difference is in the upper or lower leg but I also have slightlydifferent feet. Normally when a shop puts cleats on shoes (in my experience),they line the center up (fore and aft) with the second metatarsal bone,more or less right at the ball of the foot. I read in your cleat fittingsection that shoes larger than size 42 (I wear 47s) are a bit too longto do this and that the cleats should be moved behind the ball of the footto compensate.

So, my longer left foot is longer in part because it is flatter. Ina resting / unweighted position this difference is noticeable (like 1/4-inch)but when I stand, the difference is really slight (like 1/16-inch). I'mcurious which position I should pay attention to (weighted or not). Thelong foot is on the long leg (left leg) and the shorter foot is on theshorter leg. How might the long leg-long foot / short leg-short foot differenceact in combination? In the past, I've never had problems but since tryingto change equipment I've had foot and knee problems that are co-related(if that's a word). When I've ridden with the cleats in different fore-aftpositions, I notice that the apparent leg length difference feels exaggerated.

I guess I'm wondering what adjustments to the neutral (ball of foot)position of the cleat I should make to try and even all this out? Thanksso much for your help.
John

Dear John,
The weighted foot length difference is more appropriate to be concernedwith, and given that it is also on the longer leg, this cleat should comeaft a bit more yet, so that the foot extends further out over the pedal.The further back your cleats come, the lower the saddle you need, so witha longer left leg and foot, you can make the lower seat height appropriatefor the right leg also work for the left.
Lennard

Another spline question
Dear Lennard,
I routinely change my Dura-Ace 9-speed cassette ratios depending onthe type of race or ride that I’m doing. Unfortunately what used to bea quick easy change has become more difficult due to the fact that theribs/splines on the aluminum cassette bodies on my wheels have become damaged.The cogs appear to have dug into and deformed the splines making it verydifficult to remove the cogs. I assumed that it was just a result of thepedal forces on the cassette body overcoming the hardness of the metalbrought on by hours and hours of riding. I called the manufacturer of mywheels to inquire about why this may have happened and if I could purchasea replacement cassette body.

They said that the damage was actually caused by placing the chain whipon one of the smaller (individual) cogs when changing the cassette andthat a replacement cassette was $100! I was surprised on two fronts, firstthat an aluminum cassette body would cost $100 and second that the damagewas caused by a chain whip and not pedal force. It seems that the forcesapplied while pedaling would be much higher than those caused by a chainwhip. Is the chain whip really the problem? Also, do you have any tipson how to fix the splines on a damaged cassette body?
Sean

Dear Sean,
It's not caused by the chain whip. Yes, this is a problem, andit is one reason for the deeper splines on Campy and Shimano 10-speed bodies,as well as for putting the larger cogs (which have higher torque) on aluminumcarriers with thick splines to prevent this, at least under the large cogs.Separate steel or titanium cogs will ruin an aluminum body over its entirelength.
Lennard

Follow-up from last week
Dear Lennard,
I have a quick comment on the Tufo clincher tubular. You note thatthe rim grip comes from the tire inflation flattening the arch of the hookfooting. Do you know if there is a guideline for maximum rim width?

I've noticed a problem among CX buddies rolling these tires (particularlysince everyone wants to run them as soft as the glued on tubs) and thereis anecdotal evidence the rim width correlates to the risk of rolling.It makes sense to me, since that footing has a fixed width so a wider rimwouldn't be as tight. Or maybe it's just a tire pressure issue. I couldn'tfind any info on this at the Tufo site. Do you or the folks at Tufo haveany guidance?
Dave

From Tufo North America

Dear Lennard,
The inner rim lip distance has to be 13-14mm; it is marked on everytire label. The carbon wheel you saw at Interbike was a tubular MTB wheel,and we have tubular MTB tires available for next season.
Vladimir Juhas
www.tufonorthamerica.com

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Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides " Zinn & the Art of Mountain Bike Maintenance" and "Zinn & the Art of Road Bike Maintenance."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 Tuesday.