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Tech letters for May 31, 2002
Edited by John Stevenson
Confounded by carbon fiber? Need to sound off about superlight stuff? Tech letters is the forum for your gear-related questions and opinions. We'll attempt to answer all questions that don't require a PhD in astrophysics or industrial espionage.
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Our tech letters page at the beginning of the month produced a deluge of responses to some of the questions asked by readers. It's taken a while to organise them all, but here's the first installment of your responses on half a dozen subjects raised back then.
Contents
Aluminium disks
Bar/stem creaks
Bars and stems
Brake lever positioning
Crank Click Noise
Dura Ace 2004
Aluminium disks #1
Carbon fibre discs have been around for quite some time. They work, under one large restriction: they need to be hot. When cold, they work far, far worse than standard iron discs; even worse than stainless. Typically carbon fibre is only used on shorter courses with many turns; at places like Le Mans, they cool down too much on the long straight (Mulsanne is several miles long) to be useful at the (fairly important) hairpin at the end.
For bicycles, needless to say, carbon fibre discs would be silly; even downhillers don't get their disks seriously hot. (We're talking several hundred degrees -- hot enough to cause serious burns whenever you crash).
As far as aluminium goes, I'd think bending would become a serious problem. Standard steel discs bend far too easily as it is. I'm not sure how much weight you'd really save, in any case; the weight of the disc itself isn't a huge percentage of the total braking system weight.
Paul Spencer
USA
Aluminium disks #2
Last year at Interbike HED had a carbon disc prototype on a road bike. It used the Avid mechanical caliper and standard dura-ace levers. They said they were having problems with heat build-up. They were saying the advantages would include being able to get away with lighter carbon rims and sew-ups without heating up that area to the point of cork brake shoes not working well and sew-up glue from softening. They gave the example of Ullrich going off road in one of the TdF stages last year.
Chris
Aluminium disks #3
The hot thing for street Porsches these days is ceramic disks. They are made of silicon carbide reinforced with carbon fiber. They only come on the more expensive models, not the ordinary $80,000 machines. This material is much more durable than straight carbon fiber, and it still saves over 36 pounds. Probably less on a bike :)
Steve Ryan
Aluminium disks #4
Regarding carbon discs as an alternative, I don't believe they are a viable alternative for those of us with mortal checkbooks. Carbon discs in automotive racing applications are very, very expensive due to the length of time it takes to make the disk... up to 5 months! Now, for bicycle applications, the disk could be much thinner, so it might not take as long. (For more info, see http://www.f1mech.co.uk/brakes.htm) Regardless, the cost (high) and ease of manufacture (very difficult) would likely keep these carbon disks out of bicycling applications for some time.
David Schwabe
Milwaukee, WI, USA
Aluminium disks #5
Formula 1 race cars and airliners use a type of composite known as carbon-carbon. Rather than carbon fiber in an epoxy matrix, carbon-carbon composites are a combination of carbon fibers in a carbon-based matrix. The result is a material with extraordinary heat dissipation, strength, and low weight. However, C-C composites are a relative newcomer in the field of composites research, so they are prohibitively expensive. I would be surprised to see them on a bicycle for a good many years.
Jason Dieffenbacher
USA
Aluminium disks #6
Ceramic coated aluminum discs?
Andy Eunson
Canada
Bar/stem creaks #1
I had a similar problem with an old Syncros stem and 3T bars. I did basically the same as you. What it amounted to was after years of creaking I finally noticed a hairline crack in the weld behind the bar clamp. Appearently this was very small and unseen due to the paint. Take a very close look at your welds. I would recommend replacing it.
Jim Nowak
Bar/stem creaks #2
I've alleviated creaks/clicks by applying some light grease to the area in question. On the cranks, I've applied grease to the tapers of the spindle. On stems, applying light grease to the portion inserted into the fork seems to help.
The application of grease doesn't seem to affect the rigidity of the fastening of the parts, assuming the bolts/expander is properly torqued.
Tondeleo Hookah
Bar/stem creaks #3
I had the same problem on my road bike. Greased everything and it didn't fix it. The noise when away when I switch the front wheels. It seemed I had loose spokes rubbing against each other which creaked when I would get out of the saddle.
Juan Ramirez
Bar/stem creaks #4
Very rarely the creaking at the front of the bike will be the top cap of the headset making noise under load. Try taking the cap off altogether to see if it fixes the creak. If so, re-install it, make sure the pinch bolts on the stem are tight and then tighten the top cap down. This will not affect headset adjustment as the pinch bolts are tight. Good luck. peace.
Thomas Butler
Bar/stem creaks #5
Removing the anodization probably did more harm than good. The creaking usually comes from aluminium on aluminium. You might try putting a thin film of grease on these contact points.
Mike Vallender
Bar/stem creaks #6
Check to make sure that your quick release on the front wheel is very tight. Often this is the source of a click in the front end, particularly when out of the saddle.
Jay Dwight
USA
Bars and stems #1
In response to Noel Murphy's question as to why many threadless stems have 5-10 degrees of rise, where as the traditional "threaded" style stems are level to the ground, this is actually done to help keep your position the same, not change it. Don't forget that traditional headsets use locknuts which take up space under your stem. Therefore, even with the same amount of vertical spacers atop your headset, threadless headsets drop the bars about 1cm, which is the same amount 7 degrees of rise in the stem can compensate for.
Grant McLean
Bars and stems #2
Various companies including ITM make quill to A-head converters which are basically an expanding quill type post onto which the A-head type stem is bolted. These work fine but are not particularly light; however they do offer the convenience of a front loading handlebar mounting.
Mike Blakeney
England
Brake lever positioning #1
I used to eye ball it, with mixed results. A pro mechanic friend measures the back of the bar form the bar end to the lever clamp (no tape). Get both sides measured the same and you are in.
Dana Elliott
Brake lever positioning #2
The trick I was taught as a bike builder was to take a nice, stiff straight edge and hold it fast against the flat part at the end of the drops, pointing forward. When the tip of the lever just touches the straight edge, the hoods are in an ideal spot. It's a little difficult to use this technique if for some reason you want your levers higher or lower (esp. lower!) than usual, but still usually workable.
Michael L, Brooklyn, NY
ps: illustration attched, if you'd like to use it!
Brake lever positioning #3
I use a 3 ft level to check it and lay it across the brake hoods. I also use a straight edge from the bottom of the drops forward and position the bottom of the lever parallel or just above the straight edge.
Jim Nowak
Brake lever positioning #4
Mechanics trick is to put a yardstick across the hoods and make sure it's parallel to the top of the bar. You might try measuring from the end of the bar up with a flexible cloth seamstress measuring tape.
At least you'll get more experience wrapping bars now.
Gebhard Ebenhoech
Crank Click Noise #1
I commute to work on an old Nishiki International with a Sugino crank and bottom bracket. I'm using loose ball bearings, eleven per side. I've gotten clicking noises when the bottom bracket requires adjusting. I've never been able to figure out what could cause the noise, but have learned through experience that's what needs adjusting when I hear it. My other bikes with sealed bottom brackets have never clicked.
Glen Journeay
Poulsbo, WA
Crank click noise #2
I had the same problem. It is the titanium spindle of the pedals clicking inside the aluminium crank arm. Coat the pedal spindle with anti seize compound not grease and the problem will go away entirely.
Troy Mault
Boulder, CO
Crank click noise #3
I thought I had the same problem; a creaking, clicking noise that seemed to be coming from my crank when I pushed the pedals hard or was standing on the pedals. But after trying all kinds of solutions, a friend of mine told me to grease the interface between the fork and the front hub/skewer (carbon fork with aluminium ends). And bingo: the noise disappeared! It comes back after some hours in the rain, when the grease have been washed away.
Helge Edland
Norway
Crank click noise #4
Try using Teflon tape around the threads of the pedal. If this doesn't solve the problem, it's a possibility that your bottom bracket is making the noise. Remove bottom bracket from the frame and wrap Teflon tape around the thread before fitting back into place. Use plenty of tape, but be sure not to cross thread.
Paul Brewer
Australia
Crank click noise #5
On a couple of aluminium bikes which appeared to develop a click around the bottom bracket following rain or washing, it was the seat post, clamp and seat tube that turned out to be the source of the noise. Pulling the seat post and lightly oiling it and the clamp fixed it.
Andrew and Janet von Berky
Australia
Crank click noise #6
Sometimes the noise you hear is not the cranks at all but the rear wheel quick release. If the dropout surface is dirty (like after a rain) and your quick release is not tight, every time your torque on the cranks you can get a clicking sound. Clean the surfaces and tighten the QR. Let me know if that works for you.
John Rubcic
Crank click noise #7
Noise is very difficult to place sometimes. With new light frame materials, particularly carbon and thin aluminium, sound carries around making a headset creak sound like a pedal. I have had noise problems for years, with all kinds of bikes. And the headaches to prove it.
First, your size and riding style will make a difference. If you are big and rough, you will get more noise than a light, smooth rider. Most parts are designed, like most clothes, for an average person.
Very light parts don't last forever no matter what your weight-they flex, wear out and will fatigue and creak with time. The cost of extreme light weight. Nobody especially manufacturers, likes to talk about this. But it is a fact.
Weather makes a difference. Extremes of temperature and wet/dry will expand and contract metal so water can get into places and cause oxidation, even if it is not steel. This is magnified by different materials like titanium threads in an aluminium frame for example, because different metals expand and contract and flex and vibrate differently.
Some things to look for:
Always consider a cracked frame or fork. I have had this a few times, even when I could see no crack, and went crazy looking for the source of the noise. It showed up gradually. Once, a shop guy finally found it. We had to scrape the paint to see it clearly! This will often happen after a crash, even if you never noticed initial damage. Also, for light mountain bike frames, a short life is common.
I have heard of a creaking headset in a titanium frame that the owner sent back to the manufacturer after going crazy looking for the source. I have heard of seatposts flexing and making drivetrain-like noise when seated. And, of course, titanium frames with titanium bolts and parts are notorious for squeaks. Aluminium bottom bracket threads in an aluminium frame are gremlins as well. A speck of grit in a threaded part like a pedal can make noise.
I ride a Campy drivetrain, and the aluminium-carrier cassettes make creaking sounds (a few days after greasing them). They make slightly heavier 9-speed cassettes with individual cogs that do not have this problem. Some hi-tech wheels like Mavic Ksyriums and Cosmics creak. Light rims can develop creaking cracks at the grommets.
Check all bolts. Sweat dripping down on the bike can cause a bolt to oxidize overnight. This happens often when riding an indoor trainer, but also common climbing in the heat. This is particularly true of stem bolts and the handlebar junction. But also look at the cable housing ends. These creak a lot over time as the bars turn.(try beeswax)
The chainring bolts should be checked for being loose -then take 'em out and grease 'em just to eliminate this as a possible source.
So, all these things can be the source of noise, even cables, because you are torquing the bike the most when pushing down on the crank, often making it seem like the source. But everything flexes at that point of applying maximum force and weight. Large frames, wide bars, long stems and long cranks put a lot of leverage on things and flex a bit more. Often, these longer parts are not built any stronger or stiffer than shorter sizes(too expensive). And a tall, heavy, rough person racing an extremely light mountain bike in bad weather, no matter whose name is on it, will be asking for it. Big guys should keep to steel for lots of parts like bottom bracket axles, pedal axles and bolts in general (and even frames if you are really big). These superlight handlebars and stems are not a good idea either.
Whew! Is that enough on bike noise?! By the way, I am tall, but not super heavy and have raced on and off road for 25 years.
Michael Emberley
Dura-Ace 2004 #1
My guess is full electronic (or mektronic so to speak). This will include all the comforts of current computer/heart rate monitor functions such as usual speed, trip and also include heart rate, cadence and power out. This will all be digitally supplied via the new Shimano 'laptop' computer screen which will replace the current computer.
The screen will be linked to the cranks for wattage and cadence and front wheel for other bike functions, all via cordless remote.
The brakes will be totally redesigned to a carbon lightweight hydraulic disc set up.
This new DURAacetronic groupset will mean:
•No more gear cable (all electronic)
•Hydraulic super-lightweight disc brakes
•No need for computer or HR rate monitor as all info supplied by
'laptop 'carbon cranks
•Bloody expensive!
Betya I'm close!
Paul Turner
Dura-Ace 2004 #2
Okay, you want predictions on the 2004 Dura Ace group, here goes:
First, Carbon Fiber. There are two reasons that we won't see carbon in Shimano parts. First, because they're loathe to copy Campy, and second, because they haven't shown any interest in carbon to date.
Second, 10speed. This seems pretty likely, because it's the next logical place to go. That said, another cog plus another notch in the STI plus another level of precision in the rear derailleur equals more weight, and at the end of the day, ten cogs is probably overkill. However, there's really no reason for Shimano not to go to 10speed, so we'll probably see it. If I were them, I'd skip ten and go straight to eleven ("These amps go to eleven"), Campy eat your heart out, but that's not going to happen.
Third, bottom brackets. The D/A BB is prone to mixed reviews: It's very light, but it has a nasty tendency to fail in any number of ways. They'll keep the splines; that's a marketing thing (you have to buy the BB with the crank), but something's got to change with the BB workings. Look for a couple extra grams here; there's really no way to make that bottom bracket more reliable/durable without adding some material to it. The aluminium lockring will probably be a casualty, possibly replaced by Ti.
Fourth, STI levers. While Shimano's STIs are comfortable, smooth, and durable, they are neither light nor serviceable. The latter might or might not change (probably not; marketing again), but the former probably will. The levers themselves are big, clunky pieces of metal, and they're the most likely place to cut weight. My guess is either a redesigned profile that has some holes in it, or possibly new material (Ti levers, anyone?), or both. Once again, for fear of copying Campy (and because it's pretty useless in a race), we won't see a "drop four cogs" thumb switch.
Fifth, brakes. The dual pivot design is a good one, but compared to the DiaCompe/Cane Creek calipers and others, Shimano's brakes are pretty heavy. They're overbuilt, so some of that weight will go, but the dual pivot design will stay.
Sixth, cranks. These will not change appreciably. The aesthetics might, but the design is about as light as it can get without sacrificing stiffness. The bolt pattern will stay; marketing again.
Seventh, titanium. Campy has gotten into carbon in a big way, and as a result, Shimano will probably be hesitant to do so. That said, materials are a good way to cut weight, so at minimum, we'll see at least a few more 6Al/4V titanium fittings on a new Dura Ace group. The other end of the spectrum (the end I'd like to get my hands on) would be a titanium-oriented group, from brake levers to brake calipers to hub bodies to a full titanium cassette (which is silly, because they wear out faster, but still) to chainrings (which is not so silly). The more likely road is probably somewhere in the middle, with the order of likely titanium parts being the order listed in the previous sentence.
Eighth, a hiddenset. Everyone else is doing it; Shimano pretty much has to.
Ninth, derailleurs. Derailleurs are derailleurs; it's hard to change them dramatically. That's why everyone's derailleur design is pretty much the same. That said, with four years of product use between designs, it's going to be pretty clear where the current ones are overbuilt, and so the weight will come down some, but not much.
Tenth, Flight Deck. They've worked a lot of the kinks out of this one, so it probably won't change too much.
Eleventh, wheels and hubs. Like derailleurs, there's not too much you can do to a hub any more, except cut weight were it's unnecessary and grab someone else's patent when it expires. The hubs will stay pretty much as they are (a little lighter). The wheelsets, on the other hand, will keep going the way they're going: lighter and more aero.
Finally, pedals. We've all heard the rumors about a look-style delta cleat; if it's not available to the public by the time the 2004 group is released, it'll be a part of that group for sure.
All of this is raw speculation, based on the parts that are currently on my bike and how they can be improved, Shimano's past history, and rumors I've heard/read. The total weight will probably come down a little, even with a change to 10speed, because the STIs will probably get a lot lighter. The bottom bracket issues will probably be fixed.
Frankly, I'd like to see a Dura Ace handle bar bell, but alas, it will probably not come to pass.
Matt Herz
Seattle, USA
Dura-Ace 2004 #3
Shimano is going to try to sell a 14 speed (excluding front rings) drivetrain that is sure to be in the Dura Ace line-up when it is introduced. Only God knows how the spacing issue will work out with the chain and the cogs, but if they pull it off it will be hard for my beloved Campagnolo to top that!
Enjoy!
Philip W. Moore, Jr.
San Antonio, Texas, U.S.A.
Dura Ace 2004 #4
I was once forwarded a diagram of a patent that Shimano had for a 14 speed cassette & chain combo, designed for present 9 speed freehubs. Is 28 speed being considered for 2004? As a Shimano user I am slightly frustrated as Campy keeps improving every year and Shimano only makes minor cosmetic changes.
John P. Ericsson
Wisconsin, USA
It has to be pointed out that companies like Shimano patent lots of things that never see the light of day, just to cover themselves. A search of the US Patent Office website reveals that Shimano been issued 337 patents since 1996 that cntain the word 'bicycle'...
Dura-Ace 2004 #5
I have heard through some reasonably reliable sources that there will be some pretty cool changes ahead for the new DA. Since XTR is sticking with the trusted 9spd design, it doesn't look like DA will be jumping up to 10spd either.
The new STI levers will be constructed of carbon-fiber and so will the crankset.
Now, for the more outrageous part. I heard that they might be going to an internal rear-hub with a 9spd cassette. Thus, they will be throwing out the front derailleur altogether. Somehow, I don't see this making it to production.
And lets all hope that they make our wheels compatible!
Evan Solida
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