Wattage inversely correlated to pain

Had a bit of a strange episode where a higher wattage was more unfomfortable, although a lot less painfull than the feeling after reducing the wattage after a period of time. 30 minutes at 345W with a 6 repeats of alternating 1 minute 380W-390W and 2 min at 320W in the middle was quite interesting as backing off to 160W afterwards started to really hurt after about a minute. Increasing the wattage back up to 280-300 dulled the pain after about 30 seconds.

Anyhow, tonight set a new max 5 min average, although not quite sure how you can have a normalised power reading lower than the average ? Good thing was the average HR was nearly 10bpm lower than 1 month ago, but, the previous 5 min was out on the road.
5 minute average = 412W (410W norm ? - hr 162 avg )
Previous = 410W (416W norm - hr 171 avg)

Set a new 5 second last night.
5 second 1135W (1171 max) - max reading on ergomo was 1203W ?
Previous 1123W (1200 max) - ergomo >1200W ?
Not quite sure how the ergomo is reading >1200W when the sampling was set to 2 revs / sample as my cadence was lower than 120, which should represent 1 second...

It's not the only distortion

Trying to put together an email to FSA to try and ask them to resolve or answer what is going on and it seemed a bit long winded. At the end of the mail I was not really clear what I was asking for or how the problem could be resolved.

Putting some options together I thought I could use my Dura-Ace chainrings on the FSA spider and in the process really see if the chainring was bent by putting it on a flat surface. At first I did not know it the Dura-Ace rings would fit and then after a quick measurement and check I fit them onto the FSA spider and it almost looks good.... hmmm...

This left me with the first check to see how much the FSA chainring was out of shape, so I laid it the desk to see if it was out of shape, thinking the table was not flat I turned it round a bit, then a bit more, bit more and finally figured out the desk was not bent....

Going back to the chainring on my bike I now had a look to see if that was bent anymore and it was now showing a slight eliptical distortion and a distortion in the other plane as well that I had not noticed before (both sideways and vertical, which I had not checked for before removing the chainrings).

Now that I have probably invalidated the warranty in a quest to prove a case and in the process making my bike look a little bit more odd, anyone want to buy a bent FSA chainring, only 1,000 miles ?

Bendy FSA-SLK Crank chainrings ?

After having a power meter installed (Ergomo) I had to change my cranks from Dura Ace to FSA or more to the point the choice was limited at the time. This in itself did not seem to be much of an issue at the time, however strange things have occured since and the chainrings seem to have a life of thier own.

I did not have any means to directly measure the chape of the chainring profile, so thought the camera resolution would provide a good view of what I am seeing.

To clarify what was going on I setup my camera on a tripod (to eliminate camera shift) and then took pictures at 6 tooth increments around the chainring, which then gave me 9 shots (well about 9 in the end after about 40-50 trial shots).

From each of the pictures I took a slice at 800% enlargement (so that the pixel size was hightly visible) at the location shown on the top image and then shrunk it width ways into Excel so that the tooth profile was visible again. Each of the 9 images was processed in this way to give an end picture as shown to the right.


As a secondary means of measuring the distortion I then shrunk the row height to 0.75 and marked off each row position that correlated to the tip of the tooth on the chainring, took the row location and normalised the row numbers to a zero base, which gives the figures in the base of the picture.

The first image represents the right hand crank (chainring side) pointing upwards to 12 o'clock.

What stands out is the profile is non eliptical and distorted in 2 areas with the main distortion with the crank position around 90 degrees (each picture is a 40.75 degree inrement from (6/53)*360 degrees) that resulted from the chain in the 12 tooth sprocket on the cassette when I was training as this either creates a chain angle just enough for the pedal force to bend the chainring or the carbon fiber crank arm is distorting ?

I'm a bit puzzled as to why they are bending, although I can bend them out of shape in the opposite direction if I end up climbing in a 53-23 combination and put on a lot of pressure. That said, the doo seem to be very stable sub 1000W, it's just when you go above this some jelly seems to become involved.

Chain problems

This is what happened to one link in my Dura-Ace chain, which did not have the pin inserted correctly. After about 20 miles the chain eventually fell off..