trainers

[andrewhk]

I have not used a trainer before but have just bought a cyclo ops fluid2. Two quick questions.
1. How do you decide how hard to set the resistance of the roller against the wheel? I appreciate a trainer will always seem harder than riding on the road for a given speed etc but presumably the idea is to get it as close as possible without the wheel slipping.
2. Is it worth using a training tyre (and the hassle of changing wheel and possibly having to trim the rear deraileur etc when you change wheels).
Thanks and apologies that the questions are not ibike related but I suspect I will get far more constructive and helpful answers here than on other sites to what are no doubt basic questions.!
Andrew

[lorduintah]

Adjustment of the pressure of the tire on the rotor is pretty much explained in the setup directions - it should be enough so that your tire does not slip when trying to start very quickly.

YES - you should get a special trainer tire. Regular rubber is not going to stand up to the wear produced spinning. Buy a really cheap wheel - the weight is not an issue - put a cassette that is similar to your standard bike on the setup, use roughly the same tire pressure. If you stay with a regular tire - you will wear it out and see plenty of black shreds rub off the tire if you do not. Also - make sure you use the skewer that comes with the cyclops - not a high quality one you may have on your bike - the clamps on the cyclops can scratch them up.

Tom

[Steve_Davidson]

I have not used a trainer before but have just bought a cyclo ops fluid2. Two quick questions.
1. How do you decide how hard to set the resistance of the roller against the wheel? I appreciate a trainer will always seem harder than riding on the road for a given speed etc but presumably the idea is to get it as close as possible without the wheel slipping.
2. Is it worth using a training tyre (and the hassle of changing wheel and possibly having to trim the rear deraileur etc when you change wheels).
Thanks and apologies that the questions are not ibike related but I suspect I will get far more constructive and helpful answers here than on other sites to what are no doubt basic questions.!
Andrew

Welcome to the world of pain The turbo is a great tool for improvement (even in the summer).

A couple of things I've noted over the last few years using turbo's and rollers:-

I have never worn out a tyre on a turbo but have noticed the steel roller wears out on the turbo. I have already worn out a Tacx turbo and have started to wear a groove in my Cyclops mag + turbo. Maybe the special tyre is better in that respect.

Your bike setup (tyre pressure, roller pressure on the tyre etc.) must be as accurate as possible for consistent power readings if not using a DFPM. I use an SRM with the iAero and it's amazing how much variance you can get on the turbo if the setup is slightly different (power Vs speed).

cheers

Steve

[Ratman]

Your bike setup (tyre pressure, roller pressure on the tyre etc.) must be as accurate as possible for consistent power readings if not using a DFPM. I use an SRM with the iAero and it's amazing how much variance you can get on the turbo if the setup is slightly different (power Vs speed).

Steve, can you give us an idea of the +/-magnitude or percentage of power vs speed variance that you've seen (I don't have a DFPM, so I'm curious...)? Thanks!

[NCH1]

Hi

Just a word of caution in relation to swapping out wheels and cassettes for use on an indoor trainer. Cassettes and chains wear in together, and swapping out the cassette will reduce the longevity of your chain. If its only a cheap chain, no problems.

Nik

[Morocco Mole]

Your bike setup (tyre pressure, roller pressure on the tyre etc.) must be as accurate as possible for consistent power readings if not using a DFPM. I use an SRM with the iAero and it's amazing how much variance you can get on the turbo if the setup is slightly different (power Vs speed).

Steve, can you give us an idea of the +/-magnitude or percentage of power vs speed variance that you've seen (I don't have a DFPM, so I'm curious...)? Thanks!

One thing to understand is that the iAero is using a Power profile based on the speed of the rollers. It will not capture torque so will be unable to keep up with the DPFM during accelerations and will show potentially very large variations. At a steady state you will get much better results.

[Steve_Davidson]

[/quote]

Steve, can you give us an idea of the +/-magnitude or percentage of power vs speed variance that you've seen (I don't have a DFPM, so I'm curious...)? Thanks![/quote]

I've had about 15-17W difference at a nominal 20mph speed with a drop in tyre pressure of around 105 Vs 120psi on the rollers and a similar variation on the turbo with the roller pressure. It's worth doing a timed coast down test and check of your tyre pressures each time you ride on the turbo or just leave the bike on the turbo and check the tyre pressure regularly.

cheers


Steve

[Ratman]

Many thanks...will do that, Steve.

Steve, can you give us an idea of the +/-magnitude or percentage of power vs speed variance that you've seen (I don't have a DFPM, so I'm curious...)? Thanks![/quote]

I've had about 15-17W difference at a nominal 20mph speed with a drop in tyre pressure of around 105 Vs 120psi on the rollers and a similar variation on the turbo with the roller pressure. It's worth doing a timed coast down test and check of your tyre pressures each time you ride on the turbo or just leave the bike on the turbo and check the tyre pressure regularly.

cheers


Steve[/quote]

[doofus]

I've seen a 10-20w difference at FTP if the back axle isn't snug against the tire.

When I first put this winter's tire on, it only took 3 1/2 turns to pass the squeak test -- hold the tire at top center, rotate 1/4 turn, then smoothly -- in one motion, but don't jerk it -- rotate forward to the starting point. If it skips or squeaks, tighten it another 1/2 turn.

After holding 340w for 2x20, I retested. After 4 turns, I found 330-325w to be more accurate.

Always check tire pressure and do the squeak test before you get on the trainer.

[Ratman]

I've seen a 10-20w difference at FTP if the back axle isn't snug against the tire.

When I first put this winter's tire on, it only took 3 1/2 turns to pass the squeak test -- hold the tire at top center, rotate 1/4 turn, then smoothly -- in one motion, but don't jerk it -- rotate forward to the starting point. If it skips or squeaks, tighten it another 1/2 turn.

After holding 340w for 2x20, I retested. After 4 turns, I found 330-325w to be more accurate.

Always check tire pressure and do the squeak test before you get on the trainer.

Doof,

More good, practical advice. It sounds like you may be using a Kurt Kinetic trainer (I've been using 3 1/2 turns on my KK unit...). Again, I'm curious to know how other people's experience compares to mine. Assuming you're on a KK, were you using the 12-pound add-on flywheel during the "squeak tests" reported above or, conversely, just the 6-pound standard flywheel?

Thanks!

[doofus]

Yeah -- the KK.

The main reason I took advantage of getting a PT Pro+ wheel through my old sponsor shop was to make sure I'm getting accuate watts on the trainer. 90% of my winter and fall work is inside, and there are too many variables with the trainer mode on the iBike.

My iBIke outdoor power readings are consistent with computrainer results at a local training studio -- but the KK rides were getting a bit too high....

Good profile = good road data from iAero. No doubt about it.

With the trainer...check tires every ride...check the squeak test once a week...or better, pair the iBike with DFPM....

[doofus]

I was sceptical of the power numbers I've been getting on the trainer -- 330-340w for 2x20s

I did an hour at 315 on a properly calibrated computrainer a month ago and HR+PE were in sweet spot territory, which seemed to validate a 330+ FTP

the Kurt is a mystery. To pass the squeak test, it needs 4 turns, and I can barely put out 315w for 20min, accoring to the iBike. At 4 turns, coastdown from 20mph is 10 seconds -- waay too tight accoring to Kurt Kinetic.

When I calibrate the trainer by coastdown -- :15 sec from 20mpg, accoring to Kurt -- I get 330-340w for 20min with HR and PE in FTP territory.

The answer is DFPM -- or e-motion rollers (those are coming wednesday). With the emotions, just have the correct weight entered and check your tire pressure. No messing with getting the turns on the knob right....

[Ratman]

During my last Kurt Kinetic trainer ride, I was noticing a couple of things that may help others better "understand"/evaluate their indoor trainer experience. This first point I know has been made before, but it's especially true if you ride in a fairly cool environment (like, for me, in a small room adjoining the back of my garage -- temps in the low-mid 50's aren't unusual...). The cold fluid in the trainer this time of year provides noticeably more resistance for the first 5-10 minutes of the ride. Since I can't cross check with a DFPM, I don't know how much more power is required at a given speed, but it's clearly harder until the fluid fully warms-up. Maybe it's time for a space heater??

I also noticed that during the "squeak test" advocated by Doofus, it looked like some of the squeaking was coming from the compression/deflection/"bulging" of the tire at the roller contact point and not from slippage, per se -- perhaps you could call this "scrubbing." So, it could be possible to misinterpret squeak as slippage when it's really just tire bulge. I suppose if the sound isn't distinctly associated with the point at which you reverse directions (i.e., it's a more continuous squeak), you might wonder if it's a false alarm. I've been cranking down the pressure screw 3 1/2 turns or more, so I'm thinking to try going with a little less pressure and see if the setting still passes the squeak test while allowing a quieter overall ride. Also, I have older rims and use 700x28c tires @ 105 psi, so perhaps the wider than average width and lower pressure of the tire is causing bulge-related squeak, Of course, when using the 12 pound add-on weight, maintaining slip-free contact during accelerations is even more of a challenge.

Just a few thoughts...