dangerous carbon fractures

THE HIDDEN IMPORTANCE OF THE SEAT TUBE

You shouldn’t accept ridicule from cyclist who think they know just how important the seat tube is on a bike. For example, did you know that currently the humble seat tube is one of the most design focused areas on a carbon bike (I refer to established brands). Granted the new Cervelo P5x TT bike has done away with it but if you are a UCI compliant cyclist the seat tube is here to stay. Why so important? The biggest gains on UCI compliant road bikes these days comes from a more comfortable bike. Advances in aero tubes, BB stiffness and weight are well developed compared to rider fatigue. This is the no 1 enemy of competitive cycling. Trek’s development of the ISO Speed system in the Domane and Madone 9 is an obvious example of minimising rider fatigue without compromising frame stiffness. The genius of the Madone 9 with it’s internal flexi tube and external aero cover allows relative comfort on a sprinters bike.  Another myth is that thin seat stays provide a softer ride. The purpose of the seat stay is to push back (stay) the over-flexing seat tube. It does not allow the chain stays to flex as some think. The new thinking is to design the frame around the seat tube!

The more relative point from a carbon repair perspective is if you find a fracture anywhere on your seat tube, you should seek advice immediately. The seat tube flexes like a bow when stressed. Any flaws or cracks in the tube could compromise the structure of the whole frame. A bit like a house of cards.

 

carbon repair training

TRAINING AT CARBON BIKE REPAIR

The opening date for Carbon Bike Repair South Africa is set for 1st of September 2017. Their advanced training course is now coming to a successful conclusion before we fly them back home. However..there is one final test.  Even though they are now qualified in advanced carbon repair and restoration to Level 3, the new team are put to the ultimate test. Their task is to repair and paint restore this Trek Madone which was in 5 separate pieces. Once structural tests are successful and the graphics restored, the repairer will ride it in the next local 100km race.

So if you are ever considering getting your bike repaired in any branch of CBR, be assured that only those ‘living’ persons at Carbon Bike Repair will touch your bike.

 

MODERN CARBON BIKES & THE CONTINUAL EVOLUTION OF FRAMES

When carbon was first introduced into mainstream cycle manufacturing, carbon was seen as a ‘replacement’ for steel because it was stronger then steel (weight was still a problem) and was seen as ‘progress’. There was little consideration for the potential of ‘frame shaping’ into non conventional designs. In addition the poor relationship between alloy and carbon bonds became an issue as it turned out. There were some conceptual carbon bikes but I refer to the mainstream approach at the time. So for a while we generally went backwards in the late 80’s and early 90’s.

There are still companies such as Colnago and smaller brands who continue with carbon lug designs in some models which receive great reviews. Lugged frames allow the tailoring of frame sizes where mono-cock frames rely on mould size variety and stem lengths. Some say with lugs you can tune the ride quality best but I am not convinced.

Today’s bikes have little resemblance to the carbon bikes from 15- 20 years ago. It is such an exciting time to own a carbon bike. There is no doubt when you look at the 3 primary cycling disciplines: road, MTB and TT that road bikes, in particular from 2015 onwards, have evolved in areas such as agility, aerodynamics and comfort while making them still lighter and stiffer. I refer in particular to the higher end models where the competition to provide efficiencies are becoming harder to achieve. TT and MTB’s have carved the way for experimentation to bring new but maturised concepts to the road bike. Some suggest road bikes are starting to look more like a hybrid of mountain and TT bikes.

However –  The downside of this development seems to be where the line is drawn between the physical demands on experimental designs and consumer use. It is a mystery why some manufacturers still apply fatigue tests when they know perfectly well that carbon does not weaken with repetition as much as it does by impacts. It is the real-life effects upon the design or structure which seems to be over looked. These oversights make a common appearances in our workshops with alarming consistency. I guess it is the price you pay for progress. Just make sure your insurance policy is comprehensive enough or insure with a bike specialist insurer.

PACKING YOUR BIKE: DO’S AND DON’TS

Here are a few packing tips to help you with when it comes packing your carbon bike safely for courier delivery:

  1. Always use a dropout protector if you take the rear wheel off. It is a little plastic ‘stick’ that slots into the dropouts to stop the rear stays from being crushed in transit. Same with your forks. If you can’t get hold of one, roll up some cardboard into a tube and tape it in-between the rear dropouts. You’ll sleep better trust me!
  2. Never lean any components against a carbon surface. Wrap the frame in plastic packaging. The rubbing will damage the surface with very little effort. Carbon does not like abrasion. Secure everything in the box!
  3. Take your pedals and skewers off. Tape some cardboard over the hub ends to avoid them piercing the box.
  4. Run your chain over the big ring, adjust the rear mech in as far as it will go and lay some extra cardboard to the bottom of the box.
  5.  Before you close the box fill the rest of the space with ‘filler’ Newspapers, old packing or anything that will stop the components from rattling around inside the box.
  6. No need to wrap the packaged components with loads of tape. It just makes it harder to cut away without damaging the frame…
Look carbon dropout repair

LOOK 586 DROPOUT MODIFICATION

If you ever need an example of the level of competence within CBR here it is. A newly redesigned and injection moulded dropout to replace the original Look design.

Why did we change it? The left picture shows the original carbon dropout which is poor frankly. You can’t, without considerable risk, re-align the hanger without snapping the carbon dropout because there is NO support from the skewer when the wheel is fitted. There is too much reliance on the strength of this carbon section when, in fact, it needs to be less exposed.

This repair was for a Swiss client who loves the bike but after trying to repair it we gave up and suggested that we re-design the dropout to a different hanger system which he can replace as per normal if the hanger is damaged.

I don’t criticize the rest of the bike or the company but in our opinion this design, like some other manufacturers, have fallen short in this department. I would like to hear from Look as to why this is so. It is possible we have missed something obvious. I would be happy to share that update with you all in due course.

 

INSPECTIONS AT CARBONBIKEREPAIR: INITIAL INSPECTION

Pre and post repair inspections are key to ensuring that we have control over the quality of the weld and the warranty of our repairs.

All bikes that come into CBR are subject to an initial pre-repair inspection before we provide a final quote. There are many cases where additional fractures go undetected.

This basic inspection consists of a visual inspection in a controlled environment. This initial fee is waived if the repair is undertaken.

INSPECTIONS AT CARBONBIKEREPAIR: FULL SCAN – MICROSCOPE

Pre repair and post repair inspections are key to ensuring that we have control over the quality and the warranty of our repairs.

If you have specifically requested a ‘Full scan’ (Full Health Check) part of the scan process is still manual. The microscope is used to identify micro fractures which confirm what we are seeing on the Thermographic scan. It is best never to only rely on one source however amazing it is. Peoples lives are at risk.

INSPECTIONS AT CARBONBIKEREPAIR: FULL SCAN – THERMOGRAPHIC X-RAY

Pre repair and post repair inspections are key to ensuring that we have control over the quality and the warranty of our repairs.

Thermography is the ultimate in flaw detection. It has taken 4 years to identify a process which provides primary flaw detection using infra-red energy and 4k thermo imaging to read energy dissipation over a surface therefore providing an in-depth view of the state of the carbon. It is a myth that traditional x-ray can find all fractures when in fact what it is good for is manufacture compliance for wall thickness and anomalies such as air pockets which it reads best through cross section.This is not good enough. HD Thermography is not constrained by any shape, thickness variation or angle.

This system was developed for specific carbon inspection requirements. Not only is this effective for flaw detection at the pre-repair stage but also for post-repair inspections. We are confident at this stage of the inspection evolution that we using the best carbon flaw detection technology available to ensure conclusive results.

There are many occasions where frames are needlessly written-off.  We hope you feel more confident in asking us to check over your bike before you take someone’s word for it.