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Tech letters for April 23, 2003
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.
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Adjustable Seats
Why so much grease?
The best road bike
Mavic brakes
650C vs. 700C wheels
Campagnolo goes electronic
Campagnolo 10 speed chain links
Campagnolo 10 speed upgrade
Dura-Ace 9 speed cassette
Rapidrise with Gripshift
Tyres
Tough tyres
Adjustable Seats
Can anyone advise of a seat that has good adjustment backwards on the seat rails? I need to get further back behind the cranks than the present seat allows (Selle San Marco). I am riding a Trek 2300, 50 cm frame. I already have a Ritchey seatpost.
Grant Ludemann
New Zealand
Wednesday, April 16 2003
Grant, it sounds to me like you're a candidate for a custom frame. Your Trek 2300 has a 75 degree seat angle and if you have, say, long thighs for your height, there may not be a saddle made that will go back far enough to compensate. - JS
Why so much grease?
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I was wondering if anyone can answer this question for me. Over and over I see pros' drivetrains being smothered in heavy lube, such as these two
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If you look closely you can see they use something similar to Park's bicycle lube, which I thought should be used only in headsets and bottom brackets..
Anyone know? Or maybe a pro mechanic can answer?
Alexei Pavlov
Wednesday, April 16 2003
Those pics look to me as if the chain has just been taken out of the bag and still has some of the packing grease on it. - JS
The best road bike
I am ordering a bike and I need your guidance. I have been riding for a short time but like it very much. I had previously tried to make the US Equestrian team and have found a number of similarities: you need a good mount and you need to develop the rider's legs. I always bought the best mount. I am considering a Trek 5900 equipped with Deda Newton stem and 31.7 bar, Dura-Ace PD-7750 pedals, Campagnolo Record carbon seat post, and Bontrager Race X Lite wheels. As I said any advice in picking the ultimate road bike and the best components would be helpful especially the most comfortable seat.
Mike Dana
USA
Tuesday, April 22 2003
This is a real 'how long is a piece of string?' question. I'm sure the reposnses we get from readers will be entertaining, as everyone enjoys arguing about which bike is best, and why, but I'll head some of it off by pointing out that the most important thing is that the bike fits you properly so its comfortable and efficient. Make sure the dealer you buy from can set the bike up properly for you and takes the time to adjust or change aspects of fit such as seat height, seat fore-aft position, handlebar reach and drop and handlebar shape and width. - JS
Mavic brakes
How can you get replacement pads for the Mavic brakes, that is, do Shimano or Campagnolo pads fit in the holders?
James Lao
Tuesday, April 15 2003
650C vs. 700C wheels
All my road bikes are built to use either type of 26 inch wheels: 559 BSD rims or 650C. I like the fast acceleration, the strength and the light weight (sub 700g for a front wheel, sub 900g for a rear, bare, no skewers but with rim tape; Sun M14A rims, Ultegra hubs, 32x 14/15g spokes; nothing fancy).
The actual diameter of a 559 wheel with a sub 1in tire is just about exactly 24in; that of a 650C wheel with similar tire is 24.5 inches. A 700C wheel with similar tire is 26.5 inches.
However, you do pay a price. One, the ride is harsher for a given width of tire and for a given tire pressure. Two, some people claim that smaller wheels have more rolling resistance. The British government made a study back in the late 1800s to find out what sort of wheel rolled most easily over the new graveled roads they were starting to build at the time. They found that the reduction in friction caused by increasing diameter outweighed that caused by increasing width by a considerable factor, perhaps even a factor of 10; which is why all those sporting curricles in contemporary prints have 7 feet high wheels; and of course you have the current "29 inch" mountain bike fashion.
On the other hand, an old Bicycling article from the late '80s quoted Ernesto Colnago saying that a so called 26 inch wheel was the most efficient for smooth, modern roads.
A third price you pay is that you don't have the selection of tires that you do for 622 BSD rims (700C). I personally know of only Specialized Turbos and Conti Grands Prix in the sub 1" 559 size, while in the 650C size you're hard pressed to find anything wider than a nominal 23 mm. I get around this by using the 559 size on my commuter (with 31 mm Panaracer Paselas) and 650Cs on my go-fast bikes. I can swap between them, however, if I use normal reach, instead of the much more common short reach brakes.
I expect the principal difference between 700C and smaller wheels is largely one of feel and therefore personal preference.
Patrick Moore
Albuquerque, NM
Friday, April 18 2003
Campagnolo goes electronic #1
When Leo Da Vinci invented the bicycle, it was all about mechanical engineering. When Mavic came up with Mektronic, it didn't make sense. Cycling is moving to a 'mechatronic' age? I still love cycles to be mechanical. It's meant to be that way.
John Chan
Singapore
Wednesday, April 16 2003 (CST)
Campagnolo goes electronic #2
I own the Vetta Wireless computer (believe me this is relevant) and I have had to change the battery on the receiver at least once a month. This leads me to question why in the world would anyone want to change batteries on their drivetrain when the mechanical version works just as well. Seeing the battery carry-on near the bottle-cage made me laugh. And with more parts to break down, really, "Why?"
Richard Lu
Wednesday, April 16 2003
Campagnolo 10 speed chain links
I also snapped my 10sp Chain, twice. While visiting a bike shop in Switzerland I was recommended a Shimano Dura Ace 9sp chain to run on my Chorus 10sp group. I have been using Dura Ace ever since with no problems what so ever, and they also seem to last twice as long.
Christian Wengler
New Zealand
Wednesday, April 16 2003
Campagnolo 10 speed upgrade #1
I have two bikes with Campagnolo 10 speed rear derailleurs, cassettes, chains and shifters (one Record on which the shifters were converted from 9 speed, one mongrel with Chorus, Centaur 10 speed shifters, Daytona, and Veloce bits). I did not change the hubs, front derailleurs or chainrings. Both bikes shift as well as my two bikes with all 10 speed parts and better than two of my three bikes with all 9 speed.
If you have a Shimano hub, there are 10 speed cassettes from at least two after-market sources. I also understand that it is possible to use a 9 speed chain, although I haven't tried it myself.
Jim Smith
Calgary, Alberta
Tuesday, April 15 2003
Campagnolo 10 speed upgrade #2
Kevin,
I upgraded to 10spd Record a few weeks ago, but I have not purchased 10spd specific Record cranks yet. I've been running an older Chorus 9spd crankset with the 10spd chainwheel on. It works fine and has been smooth and trouble free so far. As usual from Campagnolo, although one has to wonder about this electronic Record stuff.
Russ Blake
York, Pa
Wednesday, April 16 2003
Campagnolo 10 speed upgrade #3
I'm running a Record 10s chain on my (old) Daytona 9s crank/chainrings without any issues.
Aki Sato
Pearl River, NY
Wednesday, April 16 2003
Campagnolo 10 speed upgrade #4
I picked up an absolute bargain on holidays in France - it was a 9-speed Campagnolo crank and the bloke in the shop even put 10-speed rings on for me! It works perfectly with the rest of my 10-speed gear. I invested the money I saved into my property fund and when it reaches its potential I'll using the earnings to buy some of those schmick-looking Record carbon cranks. By then I'll probably be too old to ride, anyway, and they'll look great on my bike up on the wall.
Damon
Australia
Thursday, April 17 2003
Campagnolo 10 speed upgrade #5
Buy a couple of TA chainrings, since they come labeled as suitable for 9/10 speeds and in the UK they only cost from about £20 each. Costs a lot less than a ten speed chainset.
Brian Palmer
Isle Of Islay, Scotland
Friday, April 18 2003
Thanks for the tip, Brian. Mine's a Lagavulin. How's the Post [http://ileach.co.uk/post/index.html] going?
Dura-Ace 9 speed cassette
I'm thinking of buying a new Dura-ace 7700 9-speed cassette which includes at least two titanium sprockets. I've heard and read that the titanium sprocket rings on Campagnolo Record 9-speed cassettes wear out quickly. Have you heard the same re: Dura-ace?
Barry Stendig
Maplewood, NJ USA
Thursday, April 10 2003
Rapidrise with Gripshift #1
Is it an original model Rapidrise derailleur (with the pulley)? The length of housing is incredibly important as housing that is too long or too short will effectively raise or lower tension on the b-pivot, potentially causing inexplicably poor shifts. Likewise rapid rise derailleurs are highly sensitive to b-tension adjustments. Also remember to make sure that the spring tension screw (located in-between the linkage plates is set in the high tension position.
On the other hand it may simply be that your shifters are too old. The plastic detents may be a bit off line, or the shifter may just be sticky. Try resurrecting this by using some Jonnisnot. Having spent time on SRT 800 shifters on high-normal derailleurs it is my opinion that they worked poorly when brand new so it might just be in your best interest to snag a newer pair of shifters that I can promise will work great with your XTR derailleur.
CJ Eder
Wednesday, April 16 2003
Rapidrise with Gripshift #2
You should purchase the SRAM Rocket Shifters as they are compatible with Shimano derailleurs. These shifters use the Shimano 1:2 ratio of cable pull (SRAM uses 1:1 ratio) All SRAM product with a number is SRAM 1:1 ratio (Example: X.0, 9.0, 7.0, 5.0, 4.0, 3.0). All SRAM product with names is Shimano compatible (example: Rocket, Attack, Centera). Both SRAM system and SRAM Shimano compatible system shifters feature the SRS technology, which blows the performance of your X-Ray shifters away. You would enjoy the great shifting that is associated with this technology. You can find more info at www.sram.com under compatible shifters.
Reece Rendall
Canada
Wednesday, April 16 2003
Rapidrise with Gripshift #3
I use the new Rapidrise XTR and Gripshift Rocket shifters and love the combo. The return spring in the shifter makes them feel very "snappy" and they shift great. X-ray shifters weren't the best ones from Gripshift. They were plagued with problems like cracking. The first question is how old are these shifters? They must be more than 5 years old. If this is the case, you may want to toss them and buy new shifters. You may want to lube them up with tons of Jonnisnot. That usually helps make them smoother. Also, check to see if the spring is okay inside.
There are many other factors involved in making shifting better. For example: ss your derailleur hanger straight? Is your derailleur worn and does it have play in the pivots? How are the jockey wheels? How old is your chain/cassette? How clean is your drivetrain? Do you have drag/friction in your cables/housing? Are you cable/housing kinked? How's your chain alignment? What about if your bike is full suspension; some designs will influence your chain tension. I hope this helps lead you in the right direction.
'Mtbike4217'
Tuesday, April 22 2003
Tyres
I thoroughly agree with that response to the Vittoria. Vittorias made me nervous in cornering, with a noticeable transition from one material to another. I rode Contis for some years, but dislike their tendency to "square out" after some wear. For some reason my favourite tire is seldom heard about or mentioned but the Specialized Works series or the Specialized Cipollini tyres seem to give great all round performance.
However, my own Vredestein experience was no better; fast wear and frequent flats made for a one time buy. One man's tire is another man's tear?
John Maynard
Ventura, CA 93001
Tuesday, April 15 2003
Tough tyres
In sight of all the punctures on Paris-Roubaix, and these super-duper 100 euro tyres someone offered to somebody.. I could offer my pair of indestructible Specialized Armadillo Turbo clinchers.
They have 2mm of rubber and a Kevlar layer underneath.. I bet they could ride that course 4 times and nothing would happen to the tyres.
Alexei Pavlov
Wednesday, April 16 2003
I suspect the problem with punctures at Paris-Roubaix and other Classics on cobbled courses is pinch-flats rather than penetration from sharp objects, in which case thicker tyre rubber and Kevlar belts won't help much. - JS
