Look who is back, Coombe pedals
Last Post 01/11/2014 10:05 AM by Nicholas Arenella. 12 Replies.
Author Messages
bobswire

Posts:290

--
01/09/2014 10:01 AM
79pmooney

Posts:1095

--
01/09/2014 12:38 PM
Too bad no-float isn't an option, I like those pedals.

Ben
ChinookPass

Posts:429

--
01/09/2014 04:41 PM
does anyone have troubles with their pedals overheating?!

they are "cool"!
79pmooney

Posts:1095

--
01/09/2014 04:50 PM
I saw that! They mean that the maximum stress under a given load is not high anywhere in the metal. That's good design, placing material where the loads are high, making all surfaces rounded and avoiding sharp edges, corners and sudden shape changes. The software that analyzes the stress displays the part being studied with the surface in different colors depending on the stress at that point. Blues and greens are low stresses, yellow is higher and red higher still. So a blue part is "cool" and a red part is "hot". Where you see the red, there is real danger of very small scratches becoming cracks leading to failure. The part that shows all blue you can scratch deeply with a knife and will still go a long ways.

Ben
79pmooney

Posts:1095

--
01/09/2014 04:54 PM
Oh, if you get your wattage high enough, your pedals WILL get hot. I haven't cranked the numbers yet but I'm guessing a few thousand kilowatts ought to warm them up a bit. (And when you get there, you will have your pick of races to win.)

Ben
zootracer

Posts:277

--
01/09/2014 05:09 PM
You had me until I saw the price.
Cosmic Kid

Posts:1058

--
01/09/2014 11:14 PM
$360?!?!?!?!!??!?!

Uh, OK.....good luck with that.
Just say "NO!" to WCP!!!!
Ride On

Posts:423

--
01/09/2014 11:25 PM
Color from finite element analysis outputs can be very misleading. Most time it just scales the data from high to low. So in one case you might see the difference between blue and red as 1 and for the next analysis the difference might be 100. It is usually a bad idea to look at the colors and draw conclusions. Colors are fun for pictures but you need to look at the actual numbers.

Also 25% more deflection could mean they had .010 inch deflection and the other guy had .0125 inch deflection. Does it really matter ? Small is small.
79pmooney

Posts:1095

--
01/10/2014 02:05 AM
I didn't see the $360. That's roughly what I have invested for pedals for all 6 bikes.

Ride On, good points. I assume Coombe uses the same load for all three pedals. If so, my point above stands. But if the loads are small enough, a scratch in the red might lead to failure in 15 years instead of 100. (That Shimano pedal looked the worst. I don't know I've ever heard of a Shimano spindle breaking.)

And same on stiffness. Can you imagine Cavendish saying he lost a race because of pedal flex? Far more unlikely, me losing anything due to pedal flex.

Ben
Ride On

Posts:423

--
01/10/2014 06:49 AM
I think the load applied to the pedals was the same ( at least it says so )

What I was trying to say is the FEA software that I am used to will try very hard to make the highest stress ( in this case ) stand out with color. That delta between the highest stress and lowest stress could be very small but one will be in red and one in blue. The software is trying to just help draw your eye to the highest point. So I assume in the Coombe pedal plot it initially also had some red ( the highest stress area relative to the other strees ) but the engineer simply changed the plot color scale so that plot showed no red. It would be easy to do for theirs and not for the competitors. Not saying they did but it would be very easy to do, just change the plot scale for their data of their pedal.

The thermal engineering guys I work with are the worst at that. They will show plots all the time with red and blue and green and your eye gets drawn to the red. Only after you start looking close do you see that red is a 120C temp and blue is 115C. You naturally think red hot, blue cold when in reality the whole dam thing is hot. They sometimes go the other way and plot the whole thing is shades of blue to make you think the whole thing is cool. Same data just different plot scales. They can plot it with all shades of red, red and blue or shades of just blue. Depends on which way they are trying to influence the discussion.
jrt1045

Posts:361

--
01/10/2014 09:14 AM
site reminds me of that crazy crankset guy from the cycling news forum and slow twitch. Frank Day with those power cranks or whatever
Cosmic Kid

Posts:1058

--
01/10/2014 11:06 AM
Posted By j t on 01/10/2014 09:14 AM
site reminds me of that crazy crankset guy from the cycling news forum and slow twitch. Frank Day with those power cranks or whatever


HAH! I had a similar reaction (although the Coombe site is better than the PowerCranks site......not much of an accomplishment, though!)
Just say "NO!" to WCP!!!!
Nick A

Posts:109

--
01/11/2014 10:05 AM
Just briefly looking at the site, looks like a good design. But then again, not really any better than Speedplay, so I wouldn't be too eager to change.

Nick


---
Active Forums 4.1