Trainers

[RapDaddyo]

I have a question for those of you who train with either a PT or SRM PM and who have a trainer. I want to identify reasonably priced trainers (e.g., <$500) that meet three criteria:

1. Variable resistance
2. Reasonably quiet
3. Speed is constant at a given power for up to an hour

The last criterion is key for what I am looking for because some trainers (e.g., mine) heat up during an interval, requiring a change of speed to maintain the same power. I'm looking for one that has a rock solid watts/speed ratio from beginning to end of an interval up to an hour. Do you own such a trainer? If so, which make and model? Thanks.

 

[acoggan]

I have a question for those of you who train with either a PT or SRM PM and who have a trainer. I want to identify reasonably priced trainers (e.g., <$500) that meet three criteria:

1. Variable resistance
2. Reasonably quiet
3. Speed is constant at a given power for up to an hour

The last criterion is key for what I am looking for because some trainers (e.g., mine) heat up during an interval, requiring a change of speed to maintain the same power. I'm looking for one that has a rock solid watts/speed ratio from beginning to end of an interval up to an hour. Do you own such a trainer? If so, which make and model? Thanks.

FWIW, I think you'll be hard-pressed to find a trainer that strictly meets all of the above criteria. The only type that wouldn't be subject to at least some degree of heat-induced fade would be a wind-braked trainer, but those of course are quite noisy. OTOH, fluid-, magnetic-, and even electromagnetically-braked would all tend to show some changes in the speed-power relationship over time. For example, even my Velodyne, which has a warm-up function that allows you to pre-heat the brake before you ever get on the bike, tends to drift by up to 5 W/h.

 

[RapDaddyo]

FWIW, I think you'll be hard-pressed to find a trainer that strictly meets all of the above criteria. The only type that wouldn't be subject to at least some degree of heat-induced fade would be a wind-braked trainer, but those of course are quite noisy. OTOH, fluid-, magnetic-, and even electromagnetically-braked would all tend to show some changes in the speed-power relationship over time. For example, even my Velodyne, which has a warm-up function that allows you to pre-heat the brake before you ever get on the bike, tends to drift by up to 5 W/h.

That's what I was afraid of. Mine (Tacx Swing) drifts by ~10% over the course of a 20min interval. So, 5W/hr is a lot more acceptable. Where I'm headed with this is a cheap substitute for training with accurate power. If a trainer meets all of the above criteria and resistance is reasonably repeatable, one can calibrate training levels by speed at a given duration. The lack of linearity between power and speed is even acceptable so long as it is relatively linear within a small range (e.g., 10%). I think such an approach trumps training by HRM or RPE by a lot.

 

[Spunout]

You'll have to get a computrainer too!

Maybe magnetic would be better, my Fluid2 varies quite a bit. There is always a massive heat-up in the first 10min where the resistance increases. Then it progressively fades(tire/drum pressure and temperature?) Keep your wattage by shifting. The stochastic display of PT negates this, maybe target constant cadence and watch AV Watts in an interval?

One constant you cannot control is tire pressure on the roller.

 

[whoawhoa]

Where I'm headed with this is a cheap substitute for training with accurate power. If a trainer meets all of the above criteria and resistance is reasonably repeatable, one can calibrate training levels by speed at a given duration. The lack of linearity between power and speed is even acceptable so long as it is relatively linear within a small range (e.g., 10%). I think such an approach trumps training by HRM or RPE by a lot.

This is what I do with my Kurt Kinetic Fluid. Frenchyge was nice enough to post some files showing very small differences in power/given speed (although he did say it seemed to take ~10 minutes for the fluid temp to stabilize.

 

[RapDaddyo]

BTW, why are you worried about speed on the traininer? Calculating chain angle efficiencies or something

No, I'm working up a training methodology based on training without a PM. It is based on using a trainer and a speedometer and identifying max speed/duration for a few specific durations (e.g., 20, 5 and 3 mins), then riding high-intensity efforts at a fixed percentage of the max speed. All that is required is a trainer that meets the criteria above. One would be training at the appropriate levels even if he didn't know how many watts he is training at. It's an alternative (and I think superior alternative) to either HRM or RPE. Second only to training with a PM (I think).

 

[RapDaddyo]

This is what I do with my Kurt Kinetic Fluid. Frenchyge was nice enough to post some files showing very small differences in power/given speed (although he did say it seemed to take ~10 minutes for the fluid temp to stabilize.

So, after ~10mins, the speed drift stops?

 

[acoggan]

You'll have to get a computrainer too!

The CompuTrainer lacks the Velodyne's warm-up mode and thermal mass (due to the 10 kg flywheel). Thus, in my experience it is even more prone to temperature-related swings in accuracy.

 

[ric_stern/RST]

The CompuTrainer lacks the Velodyne's warm-up mode and thermal mass (due to the 10 kg flywheel). Thus, in my experience it is even more prone to temperature-related swings in accuracy.

The CT's i've used (four of them) have all suffered with heat and drift. As have the other trainers i have (Tacx, and Elite Axiom). The only one that i have that doesn't drift upwards is the Cycleops electronic one (can't recall the model, but it's a trainer not the ergo) -- this one actually drifts downwards!!! (however, mine's a beta model so, production ones maybe different)

ric

 

[RapDaddyo]

For example, even my Velodyne, which has a warm-up function that allows you to pre-heat the brake before you ever get on the bike

What a cool idea, a pre-heater. Somebody over there at Velodyne thought this stuff through a bit. Cool. A bit out of the target price range, but cool nonetheless.

 

[RapDaddyo]

The only one that i have that doesn't drift upwards is the Cycleops electronic one (can't recall the model, but it's a trainer not the ergo) -- this one actually drifts downwards!!! (however, mine's a beta model so, production ones maybe different)

Hmmm, not a bad idea, to drift downwards.

 

[AndROOb]

RD, I use a Tacx 1680 flow, and although the power output is out, I have just checked a file from back in February with a 2 x 20 session on it(using PT). The first '20' shows the following average speeds/average watts:

minute 2 = 30.9mph - 250w
minute 10 = 31.0mph - 246w
minute 19 = 31mph - 244w
2nd '20':
minute 2 = 32.5mph - 257w
minute 10 = 32.5mph - 240w
minute 19 = 32.4mph -251w

What is more interesting is that I do these intervals by selecting a gear that gives me the right power to ride at a cadence (~90rpm) that fits the tempo of the beats(mixed club music at constant 180bpm) that I pedal to. I am not checking watts or speed when pedaling just keeping in time with the beats, and watching the clock. My point is that the speed seems more constant than the power .
BTW, the intervals are done using two different music CD's, hence the change in speeds.

 

[RapDaddyo]

RD, I use a Tacx 1680 flow, and although the power output is out, I have just checked a file from back in February with a 2 x 20 session on it(using PT). The first '20' shows the following average speeds/average watts:

minute 2 = 30.9mph - 250w
minute 10 = 31.0mph - 246w
minute 19 = 31mph - 244w
2nd '20':
minute 2 = 32.5mph - 257w
minute 10 = 32.5mph - 240w
minute 19 = 32.4mph -251w

What is more interesting is that I do these intervals by selecting a gear that gives me the right power to ride at a cadence (~90rpm) that fits the tempo of the beats(mixed club music at constant 180bpm) that I pedal to. I am not checking watts or speed when pedaling just keeping in time with the beats, and watching the clock. My point is that the speed seems more constant than the power .
BTW, the intervals are done using two different music CD's, hence the change in speeds.

Interesting. Looks like ~5% speed drift (upwards). Apart from the general drift, the 257W > 240W at the same speed is a little bothersome. Did you do a warmup before the first 20?

 

[AndROOb]

Interesting. Looks like ~5% speed drift (upwards). Apart from the general drift, the 257W > 240W at the same speed is a little bothersome. Did you do a warmup before the first 20?

Always. 15 minutes.

 

[Blackie]

Was just wondering whether you prematurely exclude fan trainers based on their noise? I've found by using in-ear noise cancelling earphones it completely cuts out the noise. Depends whether it affects other users though. The fan-trainer gives a much smoother, lifelike ride than the magnetic.

 

[RapDaddyo]

Was just wondering whether you prematurely exclude fan trainers based on their noise? I've found by using in-ear noise cancelling earphones it completely cuts out the noise. Depends whether it affects other users though. The fan-trainer gives a much smoother, lifelike ride than the magnetic.

Depending on where one lives (e.g., apartment), the noise can be an issue (e.g., neighbors). But, the primary goal is consistency of power/speed relationship for the duration of a typical interal (e.g., 20mins). Since my assumption is that the rider does not have a power meter, it is essential that the power/speed relationship remains constant. A 10min warmup is probably acceptable to most users, however. I'm really trying to arrive at a good answer to the question I am often asked, "I can't afford a power meter now, but I want to structure my training as precisely as possible. What can I do?" The answers now are HRM or RPE or a hill with constant grade. All three options are fairly error-prone. I'm trying to develop another option.

 

[Pureshot78]

No, I'm working up a training methodology based on training without a PM. It is based on using a trainer and a speedometer and identifying max speed/duration for a few specific durations (e.g., 20, 5 and 3 mins), then riding high-intensity efforts at a fixed percentage of the max speed. All that is required is a trainer that meets the criteria above. One would be training at the appropriate levels even if he didn't know how many watts he is training at. It's an alternative (and I think superior alternative) to either HRM or RPE. Second only to training with a PM (I think).

FWIW - I trained sans PM for about 4 months using this very idea. I did 5 minute intervals and noted the gear and cadence that I did. Improvements in my fitness were shown by being able to hold higher cadence or a harder gear.

Some random knowledge from this time: I started out doing 3x5 with 5 minute recovery in the 39x21 @ 105 rpm. I was barely able to finish the 3rd internval. This was from a nearly untrained state. after several months I progressed to the 39x17 @ 105 rpm.

I also found that moving from 39x19 @ 110 rpm to 39x17@ 100 rpm produced approximately the same fatigue as moving from 105 to 110 rpm in a given gear would do. Of course the longer the gear you get into, the more difference will be shown in speed by one RPM.

 

[RapDaddyo]

Of course the longer the gear you get into, the more difference will be shown in speed by one RPM.

Right, but think about speed as a way of fine-tuning intensity. At a power of, say, 250W, a single watt change in intensity is 1/250th. At a speed of 40 km/hr, with speed measured in 10ths, a 0.1 km/hr change is 1/400th. So, you can actually fine-tune intensity more precisely with your speedometer than with a PM. Cool, huh?

 

[dkrenik]

Right, but think about speed as a way of fine-tuning intensity. At a power of, say, 250W, a single watt change in intensity is 1/250th. At a speed of 40 km/hr, with speed measured in 10ths, a 0.1 km/hr change is 1/400th. So, you can actually fine-tune intensity more precisely with your speedometer than with a PM. Cool, huh?

I train using speed on my Krietler rollers (with headwind fan unit) as a proxy for power - still working on getting the PM

I've found this method very repeatable. The only variables I've had to watch out for are: tire pressure, my weight, and changing tire brands (changes in rolling resistance). I'll also say that after doing this for several years I believe that a bike is menat to be ridden outside

 

[RapDaddyo]

I train using speed on my Krietler rollers (with headwind fan unit) as a proxy for power - still working on getting the PM

Can you create enough resistance to do L4-L6 intervals? I owned rollers a long time ago, but I had no ability to create resistance so it was good for spinning and learning to ride smoothly but not for simulating road resistance.

I'll also say that after doing this for several years I believe that a bike is menat to be ridden outside

Well, in general, I agree with you. But, I think a trainer at less than $300 can be a good solution to riding structured high-intensity efforts if one doesn't have a PM. And, that discounts the benefits of being able to train any time, any day.