Dialing in an Ergomo with a Powertap

onebadjd

I am currently training with a power tap pro and racing with a power tap sl and have had great performance from both. I am thininking of purchasing an ergomo system for my TT bike because I can't use a disc with the power tap and because I need a backlight as most of my mid week training is in the early morning hours. I have some concerns over the accuracy of the ergomo based on what I have read. If I cross check the erogomo with the power tap, assuming the ergomo is off, can I dial it in to match the power tap? If so how and how complex would the procedure be?

peterwright

I tried the same thing a few months back and found it to be impossible. You can alter the K factor but I found that either the two would match at powers below threshold (but not above) or vice versa. I was unable to get the two to match consistently.

onebadjd

From your experience after using both meters did you choose one and get rid of the other or are you still using both and if you are how do you incorporate both? How far off were the meters either above or below threshold? What are your general observations of the ergomo after using a power tap? The reason I ask all these questions is as I stated before my need for a backlight and power pacing while using a disc. Thanx for your help.

ovalmaster

Ged rid of the PT's and get an SRM rather than buying an Ergomo. Get an LED hemet light if you need to see the screen when its dark.

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onebadjd

I have tried the LED idea didn't work to well, any suggestions? The problem with the SRM is I train on one bike and race on another (identical frames) cranks @ 172.5 and I have my TT bike, cranks @175, so for me this means at least $6,000 for two sets of cranks, ouch . I know SRM's are on ebay, but I'm not a fan of used equipment of this nature. I will give the SRM some serious thought.

Roadie_scum

Run the same length cranks on both bikes? Why the difference?

onebadjd

I have always used longer crank arms on my TT bike. I have several friends who I have trained with that are in the domestic pro peleton, they have always advised longer crank arms on my TT bike. I have followed their advice and it has seemed to work for me, but I have never used the same length crank arms on both bikes so I do not know how much of a difference they make, if any.

Roadie_scum

I have several friends in the domestic pro peloton too - but i don't look to them for biomechanical advice!

It will make 3/10ths of no difference.

Alex Simmons

As much as that,eh!

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Alex Simmons

Presume you are running under UCI rules and can't use a wheelcover for PT wheel?

I found those small led lights with the elastic band that typically wrap around the stay, work really well on the front of the helmet with the light pointing down.

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TamMan

Depends - My Ergomo was off for a while (20% below the PT). However, the readings were consistent, i.e. 20% off today, 20% off tomorrow. Tweaking the k-factor won't work.

I recently had the Ergomo re-installed (properly). Voila - it now works like a charm.

peterwright

I chose to keep my PT's as I was just testing the Ergomo for the SA agent.

Differences were around 5-10% but on a highly variable ride such as a race this made a difference of some significance.

I liked the Ergomo functionality but I did not enoy the complex nature of the installation or the inconsistency when compared to my PT.

On balance I think the Ergomo is not quite there yet - in the last few months they have realled all South African units to Germany and made some adjustments (I am not aware what) and we are now going to retest them.

acoggan

This was essentially my experience as well. That is, the response of the Ergomo Pro that I beta tested clearly wasn't linear, such that adjusting the K factor would not have solved the problem. It wasn't an issue of left-right balance, as I observed the same curvilinearity when pedaling with only my left leg. My guess is that the Ergomo b.b. can't adequately distinguish between torque and bending moments when the forces are being applied in a cyclic manner - that would explain why evaluating/calibrating one at a constant torque doesn't reveal the problem.