Moderrl Carbon Fiber Frames

There are probably many possible means of constructing carbon fiber frames but they seem to have boiled down to the means mostly used in China - where an external mold is filled with a prepreg material and then an inflatable interior mold is inflated to press the prepreg outwards to as tightly a compression as is possible with this method. The inflatable molds are quite thin since many of them tear in the removal process and remain behind and could effect the advertised weight.

Because this is a rather clumsy way of making a frame there can be voids, hollows and pimples on the inside of the frame that are not visible from the outside. These can severely compromise the strength of a frame causing cracks and complete failure. They generally use ultrasound to QC the frames for excessive voids and to get the highest acceptable production they usually put more material into these frames so that they have sufficient strength despite voids etc.

I don't know the process that Look and Time use but the insides of these frames are smooth I haven't heard of them having voids and the like so they use a rather unique process. These might be the best framesets available. Ulrasound and just tapping the frame ad listening to the sound tells you these things are REALLY solid. The Looks and Time frames I've had never gave me a moments trouble.

Trek uses male and female molds and very high pressure and makes the frames in multiple pieces that are then pressed together somewhat like lugs. I cannot tell how the top tube is connected but it has the spread force design of the headtube that prevents forces from becoming high enough there to cause rupture and in lugged designs as Colnago uses on their Italian built frames. Taiwan has also used this force spreading design technique for some of its manufacturing. The insides of these frames are smooth and voidless so that they can build more closely to the engineering limits of the material. Whatever method this is (stolen from Look I'd warrant) they have a lot less waste and good quality control.

As time goes on all of these methods are refined to improve quality control and have lower waste.

In case you didn't realize it, all bearings are press in. So the Trek BB90 and the BB30 from several companies are not handicapped purely from an engineering point of view. And it was not necessary for Trek to change to a T47 bottom bracket which required molding in aluminum sleeves on either side of the bottom bracket and using screw-in cups into which are pressed in bearings. More careful quality control of the alignment of the carbon fiber BB90 would have been a superior option since threads guarantee a misalignment no matter how slight.

The manufacturing process of old steel bikes usually had them buying a threaded bottom bracket tube and then manufacturing the frame around it. Welding or brazing on the steel tubes or lugs guaranteed distortion of the BB tube and misalignment of the cartridge bearing. Custom makers would normally use a blank bottom bracket tube and then use threaders that were connected together with a steel post that made the alignment very good. But of course threads always have a slight clearance between the threads that would allow the cartridge to have one side try to move independently from the other. This misalignment causes faster bearing wear and increased crank friction.

So theoretically the pressed in bearings of the BB90 top end Treks should have been ideal. But their experience was that they could not control the quality enough to prevent clicking and squeaking in many of them. And their means of repair was highly questionable - they would take out the standard BB bearings and insert a 37.1 mm bearing in place of the 37 mm bearing that was actually 36.9 mm. This is a hell of a lot of press-fit. A press fit this tight would cause the bearing to wear very rapidly and you'd be replacing bearing every 6 months to a year. If the original bearing fit properly and was reasonably aligned the bearing could last for years. Even the cheap Chinese junk bearings that they were using for that odd size (24 x 37 x 7) in order to fit standard Shimano cranksets.

Because these bearings are so bad, if you ever had to pull them you should always replace them. They are cheap enough and readily available at any Trek dealer or from eBay or Amazon. And the standard star punches for knocking the bearings out often puncture the seals on the bearings or dent the cages.

Rather than stick in an oversize bearing to repair the slip fit loose bearings I used a Locktite sort of compound that you had to push the bearing in with (these being loose I pushed them in by hand) and then let cure for 2 days. You put a very thin coat on the outside of the bearing with a q-tip. Well, I must have accidently perfectly aligned them because the crack slipped right in and the only rolling resistance was from the seals on the bearings and the outer water seals that Trek puts on the outside of each side.

Hard climbing revealed no noise other than the 11 speed chain noise. The Look Keo Pedals make no noise and so it is rather surprising how silent the bike is going down the road with the only noise coming from the tire friction on the ground and the freehub clicking that is little louder than the waxed chain noise.

When I wax these chains I now use a hot pot and allow them to stew in the pot for a half hour. This brings the chain up to the temperature to which the pot is set which is above the very liquid point of the wax. If you drop the chain into the pot when that wax is melted you can see air bubbles coming out of the links as the inside of the chain link clearance air is filled with wax. I cut the wax with Teflon powder which is then impregnated on the interior of the chain.

Cleaning the chain enough before waxing it is a problem so I bought an ultrasonic cleaner and use heavy duty auto grade degreasing soap and thin it a bit with water. These cleaners are surprisingly cheap at about $40. Although the mechanic I used recommended wearing in the chain first using the supplied oil on the chain, Shimano uses too light an oil to actually lube the chain and it makes a hell of a lot of noise and I don't think it is wearing in as much as wearing out. So next time I will directly go from package to cleaner and wax the new chain. 105 chains are the best bang for the buck though Connex is the longest lasting chain but you can replace the Shimano chain a couple of times for the cost of the Connex.

While around here it appears that Specialized is more common I really like the manufacturing and ride of the Trek Madone. I have a 6.9 which is more aero than the 6.2 which is the same year. The 6.9 wasn't set up to take Di2 or even the Trek off-side chainstay speedo/cadence unit.

So I installed a complete Dura-Ace group except for the crank which was Ultegra since my size DuraAce cranks are hard to come buy without having to buy them (EXTREMELY expensive) new.

The new Dura Ace manual shifting is so good I will not ever be returning to Campy despite comments here that Record can be adjusted to shift well for long times I have never been able to get them to shift perfectly for more than two weeks before you begin fiddling with shift wire tension.