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Technical Q&A with Lennard Zinn - Creaks, pops, clicks and groans
I got the galvanic corrosion and buzzin’ bottle boss blues
Dear Lennard,
I have a carbon frame road bike, and one of the water bottle bosseshas come loose. This makes for an irritating buzz, on any ride, and,I can't tighten the bolt sufficiently enough to stop the water bottle cagefrom bouncing a bit. Is there any type of epoxy, or other glue likesubstance that I can use to secure the boss?
DaveHere’s an answer to your question from carbon guru Craig Calfee
Most carbon frames use aluminum Riv-nuts for water bottle bosses.The problem is that aluminum and carbon fiber don't get along well, causingthe aluminum to corrode faster and de-bond. In our carbon frame repairbusiness, we see quite a few of these coming loose. We replace themwith plated steel Riv-nuts or our own external stud plates if the tubediameter matches. You can temporarily repair it with cyanoacrylateadhesive or "Super-glue", but it really needs to be drilled out and replaced.
Craig Calfee
www.calfeedesign.com
Light, but creaky?
Dear Lennard,
Problem: When pedaling on the down stroke on my left side while standingup I hear a single click noise. When sitting down there is no noise atall. I have changed all the chain ring bolts and even taken off the 39tooth chain ring and replaced it with a 40 chain ring since the 39 toothhad developed cracks in the lock ring bolt hole area.It is still making the noise. What could be causing this? Could it bemy Record pedals?
JPDear JP,
I would guess that it is the titanium axle of your Record pedals. Ilike the Campagnolo ProFit pedals myself, and I have four road bikes, twowith Campagnolo Record ProFit pedals and two with Campagnolo Chorus ProFitpedals. Unfortunately, though, the Record pedals have an annoying tendencyto creak, which does go away when I overhaul the pedals bearings. But itneeds to be done pretty often to avoid the creak. The Chorus pedals, however,which have steel axles, never have creaked, and I have probably gone fivetimes as long between overhauls with them as with the Record pedals. AndI know I am not the only one with this experience; I was just talking tosomeone else today complaining about his creaking Record pedals and howoften he has to overhaul them.But, as always, to isolate the creak, first switch pedals (for instance,put your mountain bike pedals and shoes on) and ride it. If the creak doesnot go away, switch wheels. If the creak still does not go away, see ifit stops when riding out of the saddle (seatpost or saddle creaking) orwhen riding with no hands on the bars (stem/bar/steering tube creak).
LennardNeeds inspection now
Dear Lennard,
Just recently I have been having trouble with my threaded headset.The problem is that whenever I get out of the saddle and put pressure onthe handlebar (which is a road bike by the way) it makes a cracking orcreaking sound. So I checked the bearings and even changed them and adjustedit really well with smooth turning, but still I end up with the same results.So if you have any idea what it could be, it would really be helpful tome.
GianDear Gian,
If you’ve isolated the creak to that area (see my answer above formethods of isolating it), it's probably the stem moving inside of the steeringtube, or the bar moving inside of the stem. The steerer may be bulged frommany expansions. It should get better with a lot of grease slathered allover the stem quill as well as inside of the stem clamp around the handlebar.But for safety’s sake, you ought to pull the fork out and look at it first.It could be so bulged it is about to fail, or it could be splitting downthe groove cut down the side for the toothed headset washer. Also, inspectthe bar and the stem for cracks.
LennardHi Lennard,
I recently read a letter asking about aluminumflakes embedded in brake pads damaging carbon rims. I've always beencurious about this with respect to Zipp carbon rims specifically, whichhave a ceramic brake track. Would the ceramic brake track on theZipp carbon rims be as susceptible to damage by these embedded aluminumflakes in the brake blocks?Could I use Zipp carbon wheels and aluminum rimed wheels interchangeablyw/o having to swap out the pads? Then regarding the Zipp ceramic braketrack, do you know if it is as durable as the ceramic brake track usedon aluminum rims which greatly improves the longevity of the rims, especiallymountain rims but requires the use of special, harder ceramic brake pads?
FredHere is an answer to your question from Zipp
The Silica Ceramic brake track on ZIPP rims is very, very durable,though quite different then the metal on alloy coated ceramic rims.It provides for a great braking surface in dry and wet conditions....infact, it is quite a bit better than alloy in the wet....but it can be damagedfrom massive heat build up when standard pads are melted onto the rim brakingsurface or when it starts building standard material up onto the rim surfacein uneven patches.This is something we used to see quite a bit of on older two- or three-year-oldrims that were owned by people in flat parts of the country who visitedmountainous areas. They would use the rims with a lot of excess brakingand begin to melt the standard pads onto the braking surface of the rimdepositing material in uneven lumps. Once it was on the wheel, itwas very hard to get off and damaged the surface under the Silica Ceramicbraking surface. We never saw this on wheels used by Pros, only byguys who used the brakes excessively usually when on trips.
Today we see a lot less of the above because the rims are, well, better.It is a game we play back and fourth....
What we do see is rims that have been weakened from excess brakingwith standard pads. What I am talking about is badly melting, burningstandard brake pads onto the rim...Small cracks then can start to appearon the rims weakened points after some time (2-3 years) and we tell thepoor guy that he should be using ZIPP pads that won't melt.
The ZIPP brake blocks are made for us by Koolstop out of materialswe supply to them. Again they are quite different than any otherbrake block. The biggest difference is in the materials used to make upthe brake block. First, they melt at a temperature 75-100 degrees hotterthan any other standard or carbon block. Second, when they melt,they turn into a powder that blows away. Third, being a harder materialthat blows away, it seldom holds onto anything. Part of the magicis in the Carbon Mesophase pitch material included in the brake block....itis little bits of material that moves heat very quickly way from the pad/rimseveral times (3-4 times) faster than copper wire.
Now I should point out we have been talking about tubular tire wheelsof which we sell thousands...but the very things which make the ZIPP brakeblock great for tubular wheels also make it great for using with clincherson alloy rims and for alloy rims in general as well. The problemsassociated with using standard brake blocks (melting, damaging the rimwith included bits) or other soft pads for carbon (quick wear, meltingetc,) virtually disappear when using the ZIPP carbon pads for either typeof rim.
So, could you use the alloy rim and carbon rim with the same standardpad? Yes, for a lot of folks it would work okay....for 2-3 yearsor 4-5 years until the carbon rim got "dirty" with build up material andthen warped/cracked. For some folks it would work pretty much forever.....untilthey got into a situation where they burned up their standard pads on therim. To avoid this problem we suggest that you use the ZIPPbrake pads all of the time, but some folks continue to use standard padswith no problems. (I am talking TT folks, triathletes and high-end recreationalriders in flat parts of the country.) If you are going to ride hard....theharder the better...you should use the ZIPP pads and no other. Theywork well when switching between wheels, or when riding with tubulars allthe time.
We also suggest cleaning the tubular rims when you switch to ZIPP padsafter burning on standard pads. Use a Scotch Brite pad for woodworking,the very finest works best (You can get these in the paint store), soakedin Acetone to work the rubber loose. You can also rub the brake padswith the Scotch Brite when switching alloy to carbon rims just to be extracareful. Me, I have ridden tubular wheels for years and cleaned mywheels maybe...oh, once a year. Yeah, I know...I'm bad, but usingthe tubbies only and ZIPP pads I don't need much more cleaning than that!
Bill Vance
ZIPP Speed Weaponry
Warning
Dear readers,
And speaking of acetone, I got a lot of letters complaining about thepostings a few weeks ago on how to clean tubular cement off of carbon rims,all of which involved acetone. To paraphrase, the writers’ concern wasabout using such a dangerous solvent without warnings about not breathingit or getting it on the skin. So here it is: avoid using acetone, but ifyou are going to use acetone, use it in a well-ventilated area, wear rubbergloves, a respirator and safety glasses.
Lennard
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.
