My Rides

Sunday, January 23, 2011

New Trainer

In the past couple of weeks, my aerobic speed went from 14 mph (80 watt - if the published power/speed data is to be believed) to 16 mph (>100 watt) on 1-2 hour Endurance Miles (EM) portion of my workouts.  I had read about my trainer (Blackburn Trakstand Ultra) having some varying resistance and therefore inconsistent power vs. speed behavior.  While still in the aerobic/lactate threshold part of my training, I took the trainer apart, inspected & cleaned (alcohol) the friction plate, and greased the drive-shaft as recommended by internet sages.  Before and after spins told me that my unit was working fine (no difference noted before/after)...

Since being reassured that my trainer is A-OK I've started my peak intervals (at/near VO2_max).  The promise of the training is that these peak intervals improve aerobic speed/power...  Well, after a week where I thought I was seeing rapid and very significant  improvements in my aerobic speed - I was riding at 21-22 mph (>200 watt) for an hour at heart-rate of 120-130! I decided to take apart my trainer, again, and double check that it's me making more power and not the trainer dissipating less.

I made this realization about my potential lack of awesome-ness about 15 minutes into a ride.  So, I dismantled the trainer, and noticed pretty obvious/visible glazing on the friction plate.

I wiped both the flywheel and friction plate with alcohol, then sanded with 400 grit paper on a block, from the center outward (seemed to make sense), then re-wiped.  After drying, everything looked like new.  After reassembling, sure enough my aerobic speed dropped back to about 16 mph.  Oh well...

After an hour of aerobic spinning, I started my intervals - 12 minute over-unders - Alternating 2 minutes @ lactate threshold (LT), 2 minutes climbing repeat (near to slightly above LT, but low cadence).

  • My speeds for the first 2 min / 2 min block were 21-22/22-23 mph.  
  • In the 2nd block, for the same heart-rate & perceived effort, speeds were 17-18/19-20 mph (OK, maybe things change after warm-up, no big deal).  
  • In the last 2 min /2 min the resistance severely dropped, and I was doing 25-27 mph and couldn't even do the climbing repeat (well I could, but it was no effort) - I was in the highest gear on my bike (44-12) and spinning 105 RPM @ 30 mph with my heart-rate dropping, when I'm supposed to spin @ 70-85 RPM (and I struggle to keep my heart-rate below the max).  
I slowed to my aerobic pace, took a bathroom break, and returned, hoping to find resistance had returned (and maybe I just needed a fan pointed at the resistance unit).  Nope, either I'm Lance Armstrong or this thing passed warmed-up to burned out...  (I was no Mellow Johnnny at this point)

I cleaned and re-assembled the unit, again, but same thing - the friction plate quickly glazes at speeds over 16 mph.  I put in the extra bearings (to increase the resistance, in spite of the glazing), but at this point my workout was upset, and I don't have the patience to try to re-engineer the thing to maintain my workout schedule.  Maybe I'll find some help from Blackburn's customer service...

I'd like to move to training with power (vs. heart-rate) for all the reasons experts advise.  I know I can't expect great absolute accuracy without a power-meter, but I should at least be able to expect some consistency...

A little research reveals the Kurt Kinetic Road Machine is very accurate/repeatable, as well as reliable.  They state:  "Only fluid trainer with measurable, repeatable power curve."  You can click the word "power curve" and actually find a power curve.  Elsewhere on the site, they offer the formula, with coefficients, their trainer is calibrated/designed to follow.
"...using the following cubic function: P = (5.244820) * S + (0.01968) * S3. S=speed in miles per hour, P=power in Watts"
Not that this formula is anything new or mysterious - you can find it on wikipedia - but finding it actually published, and easy to find, by the people making a product is reassuring.  Getting the same for my Blackburn took considerable hunting and downloading to find.  I ordered one today, and it will be here for my Tuesday workout.  Hopefully Blackburn can help me at least get my former trainer in good shape as a back-up.