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Technical Q&A with Lennard Zinn – Can I soften that ride?

  • By Lennard Zinn
  • Published Jan. 11, 2005
  • Updated Aug. 29, 2010 at 10:39 PM EST

By Lennard Zinn

Technical Q&A with Lennard Zinn – Can I soften that ride?

Photo:

Oh my achin’ back
Dear Lennard,
My bones are getting stiff and achy, and I am looking for a way tosoften my every day/training bike, a Cannondale CAAD 5 with the stock all-carbonfork. The bike fits me like a glove and is very responsive.Would a carbon bar and stem combination damp the ride and add comfort,or are carbon bars just as stiff and noncompliant as alloy bars?Are any carbon bars “softer” than others? Have you ridden Specialized’sRoubaix? Is there a significant improvement in the ride? Isthere a real tradeoff in performance? My 59-year-old neck, arms andback thank you!
Bill

Dear Bill,
I have not ridden a Roubaix, especially on a rough surface, so I cannotsay whether it works or not. My concern about it has to do with my experiencewith shimmy, which we have so often addressed here. I am sure the elastomerinserts on this bike and on other competing designs will damp high-frequencyvibration. I wonder, however, if it will damp low-frequency ones as effectively.The thing I have found with shimmy is that the frequency of vibration ofa bike drops a lot as soon as there is a rider aboard. And the heavierthe rider, the lower the resonant frequency of the bike and rider combination.

I will leave it to some carbon handlebar manufacturers to answer yourquestion on that subject. As you can see, they are not all of one mindon the subject.
Lennard

From ITM
In effect, the use of a carbon bar and stem combo does not make therider more comfortable in term of damping the ride.

The rider saves weight on the bike AND gains in stiffness. Certain ridersare looking for this, but not for comfort.

What can make a carbon bar “softer” is the use of Kevlar, but the moreyou put into the bar, the heavier it becomes.

As for the bar, we suggest the use of an alloy bar, BUT in 25.8mm NOToversize.
The bars in the Light Alloy 2000-6000-7000 family have to be heat treatedand/or shot-peened, and once these processes are accomplished, they becomestiff.

(We have seen on the Web the Specialized ‘05 Roubaix with Zertz. Wereally do not know if this system would work or not. In Paris-Roubaix,the riders have been trying suspension forks, suspension stems and suspensionframes, and of the bikes used by the winners, how many were using thosecomponents?)

Other suggestions: Check the fork. Do use a fork with curved bladesrather than straight. Furthermore, it is important to use wheels with properrims and spokes. You know how different a low profile rim rides in comparisonwith high profile. And finally, the main “responsible” part is the frame!
Flavio Tizian
ITM

From Deda
Regarding handlebars, it is not easy to answer. The supposed “flex”of the handlebars comes from the “quill age”, when stems were 2D forgedand the horizontal length was pretty “slim”, so, especially during climbsor hard pushing and pulling on the bar, you could have the feeling of someflex, (mostly a little rotation of that part of stem).

Now, carbon; mmmhmmm, in my tests, carbon is always stiffer (lessdeformation for the same load) than alloy. I know the future is coming,I am looking closely at products like the “Aliante” of Selle Royal. ButI cannot predict a fast arrival of “controlled flexibility” of handlebars.For the comfort, and the back pain, of our reader I would be more focusedon tires, tires, tires.

At the end of the day, the rider touches the bike through handlebartape, saddle and shoes, but the bike touches the ground ONLY at the tires.
You know how important a supple tire sidewall is.
Fulvio Acquati
Deda Elementi

From Easton
The damping characteristics of carbon fiber would definitely improvethe quality of his ride in terms of comfort. The carbon road barsin particular have a very nice feel and really smooth out the ride.
John Harrington
Vice President- Bicycle Products
Easton Sports, Inc

From Stella Azzurra
Carbon fiber parts are generally considered stiffer, that’s why manypeople wrap extra soft tapes on bars or gel pads underneath them. I donot have comparative research among all the carbon bars, so it’s difficultto say if there are carbon bars that are stiffer than others. I would suggesttrying a carbon bar, and depending on the feeling, apply a thick and softtape (i.e. Tecno Spugna extra soft) or a thinner tape (Tecno Spugna standarddensity) to absorb the vibrations. I am sure that extra light aluminumbars are very flexible because the light weight is obtained by the lackof material and so the result is generally a weak and flexible light bar.Instead, at the same weight, with a carbon fiber bar you can have a strong,safe and stiff product.
Stefano Alberti
www.stellaazzurra.com

Worth the price?
Dear Lennard,
The new Shimano Hollowtech II stuff looks nice, but the price is aboutdouble the old stuff. Any idea if the durability vis-à-visthe old stuff justifies spending the extra cash? I go through theold Hollowtech bottom brackets pretty quickly on the MB – about 2K miles,but replacement BB’s are cheap. Any feel yet if the new stuff withthe larger outboard bearings will last significantly longer? As well,what do people do when the new HTII BB’s are shot? Is the HTII stuffrebuildable? I don’t see any BB’s for these cranks available on anyWeb site – everything is sold as a crank/BB set, but the stuff has beenout long enough that surely some folks are ready for new bearings.

I loved all that stuff on cleaning the cassette. I’m often accused bymy buds of being over-zealous about maintenance, but some of those folksmake me look positively normal – normal being a relative term.
Steve

Dear Steve,
First, for your last comment, I’ve had people write wondering if theycan come over and clean their cogs in my living room or with a power washerinside my shop. (I said no.) I’m including one more letter on this subjecttoday. That ought to do it, I think!

On to your main question: As you probably saw from our crank stiffnesstests in VeloNews, you gain a lot of stiffness as well as a reductionin weight with these cranks. That ought to be enough for you to shell outthe big bucks for them, but you want durability, too? Just kidding. Actually,my experience has been that Shimano and most other integrated-spindle bottombrackets wear reasonably well with the one caveat being that they are unforgivingwhen it comes to frame tolerances. Shimanos and all of the others I haveseen save for Truvativ are sensitive to proper facing and tapping of thebottom bracket shell, since there is no system to take up any asymmetry.The Truvativ system, which I currently have on one of my bikes (albeitone that has a perfectly tapped and faced bottom bracket shell-see thephoto) is designed so that the non-drive bearing bears any axial (i.e.,lateral) loads while the drive-side bearing only bears radial loads (loadsdirected along lines radiating out from the center of the spindle).

The drive-side bearing can float axially (side-to-side) on the spindlewhile the non-drive bearing is pinched between a shoulder on the spindleand the non-drive crankarm. Most systems instead have a constant-diameterspindle with no shoulder, and its lateral motion in either direction isfree until the separable arm (usually the left, except in the case of RaceFace) is pushed against the bearing face and clamped there. If the bottombracket is not tapped properly so that the axes of the threads are notconcentric (centered around the same line through the center of the shell)or if the faces of the shell are not perpendicular to this centerline andparallel to each other, the bearings will be slightly cocked relative toeach other. This means that there will always be twisting loads on thebearings. In other words, there will always be some axial (side) load onthe bearings, and standard cartridge bearings (which these bottom bracketsgenerally have) are designed only to take radial loads, not axial loads,and will thus wear quickly.

The Truvativ bearing system can allow for some radial clearance betweenthe non-drive bearing and spindle, thus allowing for greater frame non-concentricity/non-perpendicularitywithout affecting the bearings. When you tighten the non-drive-side crankbolt, the crankarm will pinch the inner race of the non-drive bearing betweenthe crankarm and spindle shoulder. The non-drive bearing will be fixedboth axially and radially to the spindle, while the drive-side bearingis only fixed in the radial direction. However, unlike Shimano-style armswhich are only tightened finger-tight against the bearing with a smalldisc-shaped splined tool and then pinched onto the spindle by pinch bolts,the Truvativ system requires that the non-drive crankarm be tightened toits full specified torque value so that it actually clamps the non-drivebearing. If it is not tightened enough, the system will have play and thenon-drive crankarm can loosen.

If your bottom bracket shell is machined correctly, I imagine any integrated-spindlesystem will wear at least as well as standard cartridge bottom bracketswith oversized spindles (Shimano Octalink or ISIS). The bearings externalto the bottom bracket shell are larger in diameter, and probably in ballsize and number, than ISIS or Octalink BBs with bearings internal to theBB shell. Wear on internal-bearing oversized-spindle bottom brackets canbe rapid, because there is little room between the big spindle and theinside of the shell for big bearings.

As for when integrated-spindle bottom brackets do wear out, the bearingsand cups alone are certainly replaceable. (You of course cannot pull outthe spindle and replace that!) Race Face’s X-Type external BB bearing cupsare available separately and are compatible with Shimano XTR, XT and Saintintegrated-spindle cranks and probably would run you $30-$40 a set.
Lennard

The final word on cleaning cogs?
Lennard,
I am surprised about how many readers feel so strongly about cleaningcogs. It seems that there is a lack of knowledge about how it isdone by pro mechanics, or the reasons that pros make these choices.Despite the variety of methods used by your readers, pro mechanics mostoften do this cleaning in a similar manner, for like-minded reasons.As a pro mechanic, you typically have double-digit numbers of bikes andwheelsets to clean in one session. During a stage race this may bea daily task, in addition to washing and prepping cars, changing hotels,etc. Time is of the essence. Pros choose a routine [wash framesfirst, then wheelsets, then reassemble, check bolts, lube, etc.] basedon the efficient use of time and the need to eliminate any redundancy.

The major point about pro bikes that some readers may miss, is thatif the bike is getting washed daily, it never can get that dirty.Washing is also the best way for a mechanic to get a close look at everythingon the bike. Small tire cuts, cracked parts, and fatigued equipmentare best uncovered during a daily wash and tune than under the stress ofracing. Cogsets do not get gooped up if they get daily attention.

When it comes to the choice of cleaners, ease and efficiency also dictateuse. For soap, dishwashing soap is the choice. It gives yougreat suds from a small volume, you can get it in pleasant scents and itdoes not kill your hands. All things to think about when you haveyour hands in a soapy bucket for 2+ hours a day. In some cases, thissoapy mixture from the wash bucket can effectively clean cogsets from dailyuse. This all depends on the weather from the day’s stage, dirt anddust on the roads, and your lube choice. More typically you haveto use something more aggressive for the chain, chainrings and cogs.Having a sponsor [like Pedro’s for instance] may give you unlimited accessto a more aggressive cleaner for cogs. This is a great situationfor the mechanic. However it has been my experience that these cleanersare not always strong enough to prevent you from spending additional timeand energy cleaning drivetrain parts. Especially after wet stageson dirty roads. Here is where stronger agents like diesel come in.

I have personally written against using diesel in the past, howeveryou have to weigh the pros and cons.

PRO: diesel is VERY effective and quick in small amounts for cleaningdrivetrains. Typically pro mechanics will have a small container[I have a used an old water bottle with the top cut off in the past] anddiesel brush. Two ounces of diesel may last you a week of cleaning12+ bikes a day. The same cleaning task may require gallons of the’environmentally safe cleaner’. As Lennard points out, used cleanerwith drivetrain goop in it is not safe. Diesel is also available everywhere,especially in Europe. Have you ever tried to find a bottle of ‘bio-degreaser’or even Simple Green in Silver City, NM [Tour of Gila] at 11:30 pm on aThursday night? Diesel pumps are on 24 hours a day in thattown. Most big pro team trucks run on diesel and most of us havea spare can of diesel in the back of the truck at all times. CON:Diesel is horrible for the environment. Period. Your readersacknowledge this with great vigor and they are right. So is a hugeamount of ‘bio-degreaser’ filled with drivetrain goop. So is wastemotor oil.

I have joked this year in Philly with Chad [Healthnet], Jim [WebCor],Eva [Colavita] and Ken [T-Mobile] that one of the big lube companies shouldcome out with a product called something like, ‘Bio-diesel’ or ‘Dieseltech’as a cleaner. But it is not as simple to design a product that hasall of the Pros of diesel and none of the Cons. Until then, dieselwill still be used. But it is not done in a haphazard manner.All of the other pro mechanics I talked to in Philly this year acknowledgedthe harmful effects of diesel use, but were also aware of the increasedamount and the decreased efficiency of using a ‘bio-friendly’ product.In the end none of us want to hurt the environment or ourselves on thejob.

The reality of the task at hand ultimately leads to the best solution.In some cases diesel is a solution. I think that most of the readersfail to see the conditions that pro mechanics work under and the reasonthat they would resort to this product. There were many nights aftermidnight this past year where I was still up washing bikes [in some casesin the rain and sub 40 degree weather]. In these cases I wish onlyhad to wash my own bike once a week with unlimited time and resources asit sounds like is more typical of your readers. Different scenariosrequire different approaches. In the end, I am very concerned withthe environment and excellence in my job performance.

We all should be. I hope that this helps shed a little light onthe ‘other side’.
Chris Davidson
T-Mobile Cycling Team
Shimano Multi-Service


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.

FILED UNDER: Bikes and Tech / Technical FAQ TAGS: / / /

Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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