Technical Q&A with Lennard Zinn – Consumer issues; Commuter issues and the usual follow-up letters

By Lennard Zinn

Sure, they’re all like that, sir
Dear Lennard,
I go through at least two chains (Shimano 7701) every year and replacethem myself. They have always come sealed in a plastic package withtwo connecting pins. I recently ordered a couple of Shimano 9-speedchains (7701) from an Internet retailer. When they arrived they werein boxes for a 10-speed chain (CN 7800) and were not sealed in the usualplastic wrapper. The connecting pin was also already partially insertedinto the outer link with the guide snapped off. All 116 links werestill there. The customer service rep’ told me this is the way theycame from Shimano and there was “nothing wrong with them.” Is thisa plausible explanation?What do you use to clean a brand new chain to get rid of that stickypacking substance?
KrisDear Kris,
No, that is not a plausible explanation. I’m quite sure that they wouldnot have come that way from Shimano. I’d send ‘em back.I don’t remove the “cosmolene” lubricant from new chains with a solvent.That stuff provides good lubrication deep inside the chain, and if youare too thorough with removing it with a solvent, you might end up witha squeaking chain that has no lube where you really need it, namely betweenthe plates and under the rollers. Solvents may continue to be wet and displaceany lubricant you try to get to penetrate in there.Instead, from starting with the very first ride, I apply ProGold ProLinkafter every ride. After a couple of weeks (less in wet or dirty conditions),that sticky stuff is gone, and the chain is running great.
LennardThe joy of ceramics
Dear Lennard,
I just finished your article in VeloNews (issue 21)and havea question. Would it be beneficial to replace steel bearing in a standardsealed bearing BB with ceramics? I have seen advertisements for loose
ceramic bearings, and have wondered about the efficacy of ceramicswithin an existing sealed unit (non outboard). Also, what do you thinkabout replacing steel bearing in a cup and cone bottom bracket, somethingakin to the old Campagnolo Super Record?
KevinDear Kevin,
Yes, I think it would be beneficial to replace the sealed steel cartridgebearings with ceramic ones. As for putting loose ceramic balls into anexisting cartridge, I’ll be impressed if you can get one apart and backtogether without damaging it. If you can, then yes, the ceramic balls willbe a benefit.And certainly the ceramic loose balls will run better in a loose-ballbottom bracket, like the old Super Record.
LennardRoad Warrior
Dear Lennard,
During the summer months, I commute on a custom road bike with Ultegra9. During the winter, I use a Stumpjumper with slicks. I likethe greater confidence on the Stumpjumper, but I want just a little betterperformance in speed. If I change to a 48/36/26 touring crank, whatelse will I need to change?
TJWDear TJW,
You will need a longer chain. Your front derailleur (raised up of course)should work okay with it. If it is a bottom-pull front derailleur, youwill need a longer front shift cable as well.
LennardMeet the new boss
Dear Lennard,
I’m trying to finish building up a Ridley aluminum cross frame thatI’ll be using as a winter commuter, using a 53T road crank instead of asmaller cross crank. Doing this, the front derailleur clamp landsexactly on the water bottle boss. My original plan was to find away around this with a different derailleur or using a braze-on with anadapter, but I just ran into another issue: in threading the bolt intothe same water bottle boss, the insert came loose. This has createdboth new options and problems – can you tell me which might be thebest solution? Can I have new bosses installed in a better location?If I don’t move them, what’s the best repair for the loose one? Willsomething like JB Weld work?
JimDear Jim,
Indeed, you could have new bottle bosses riveted in, but you wouldstill have those gaping holes in your tubes. The best repair for a looseone is to re-crimp it with a bottle-boss riveter tool. I would suspectthat epoxy would not last long with a full bottle in that cage, bouncingaround on ‘cross courses, but, hey, what do you have to lose? Give it atry.
And I would try a low-clamp, downswing (as opposed to topswing – theseare both Shimano distinctions) mountain-bike front derailleur on there.
LennardFeedback on lastweek’s column
Dear Lennard,
You probably already have comments on this from others, but the equationyou provide for terminal velocity is not strictly correct. The areathat is used must include a Drag Coefficient (Cd) as well as just the frontalarea. For example, a round flat plate has a drag coefficient on the orderof 1 whereas a hemisphere of the same diameter (and cross-sectional area)with the flat end facing downstream has a Cd of about .38, and a true airfoilof the same diameter might have Cd of 0.1 or below, depending on diameterto length, design, and a number of other factors. (An Introduction to Fluid Mechanics, Fox and McDonald) The Cd changes some with Reynolds number,but in any case needs to be included in terminal velocity calculation.I would guess that Cd values based on wind tunnel testing for time trialriders exist out in the literature somewhere.
RogerMake it sticky?
Dear Lennard,
Regarding the slipping carbon seatpost on carbon frames, another solutionis to apply a little energy gel (GU, Powergel, Clifshot, etc.) at the tophalf inch where the seat post binder bolt is. Affordable, and easy. Worksfor me.
RandyDear Lennard,
In your last column (under “A spherical solution”) you suggested afix for carbon-on-carbon seatpost slippage. I, too, had a lot of troublewith my R2.5 and now the R3 with the seat post slipping. After over-tighteningthe seat post and having to purchase a new collar, I was told to sandpaperthe seat post where it enters the frame. That seems to have solvedmy problem with slippage.
MarkTreating the tip
Dear Lennard,
I’m an engineer with a medical device company. We use stainlessstranded cable and, for see-if-it’ll-work prototypes, we solder a lot.We’ve had really good success with lead-free silver solder and acid flux.The hobby shops all have it and it usually comes with a water-soluble flux.We set our irons pretty hot but heat loads vary by diameter so it’s reallysomething one needs to play with. I’ve also had good success pre-heatingthe wire in a furnace to 400° F or so. If you’re quick to theiron it makes it a whole lot easier because you don’t have to manage thethermal changes and some of the oil will have flashed off.I don’t recommend this in one’s kitchen, however, because mainstreamcable is well oiled during processing and it’ll stink and make your nextroast taste nasty. Since lead-free is obviously a requirement inmy industry, it’s relatively safe, but remember, the flux is nasty stuffso wear gloves please. Oh yeah…and a small metal container is a bighelp with the flux. I put a puddle of flux into the container, laythe cable in the flux, and place the iron right onto the tinning locationuntil you can see most of the crud has come off, at which time I applymy solder.Oh yeah…hydrochloric acid is a good recommendation, but you don’t needthe brown-bottle chemistry lab stuff. The diluted muriatic acid fromthe hardware store works fine sometimes. It’s no guarantee, evenwhen using ultrasound energy. I’ve had circumstances where I’ve thrownthe whole kitchen sink at a cable and not had good success. In thesecases the cores were drawing flux fine but the outer strands weren’t.Go figure. In the end, turning up the heat and using more flux seemedto work best.For my own bike I use a different method entirely. It’s a versionof electro-cutting or electro-welding. I’m fortunate enough to havea laser welder in my lab. I cut my cables to length, pull them backout, and take them to the office. I clean my cables in an ultrasoniccleaner (dish detergent, IPA rinse, DI water rinse). I follow thatup with a trip to the laser welder.
ChrisDear Lennard,
I had been also frustrated by not being able to solder cables untilI found a better way. Heat the cable with a propane torch until it glowsred in the spot where you want the cable to end, and at the same time,twist the cable with a pair of vice grips in the same direction the cableis wound. The cable will break in the middle of the glowing spot aftera number of turns, much like molten glass, it narrows and fuses to a permanentend that is better than a soldered cable.Of course you should wear safety glasses, be sure there are no flammableproducts around you and work in a well-ventilated area, etc.
Keith

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