Which turbo

richardjallen

I don't want to grind away my new bike over winter or shell out £300-400 on a winter training ride and another £100 on lights so I thought a turbo trainer for around £100-£150 would solve everything in one.

I understand a fluid turbo is quieter but what's recommended in the £100-150 bracket. Is it going to be all that loud?

campagsarge

Check out this thread - Monty Dog gives a good run down of the various types.

http://www.bikeradar.com/forums/viewtop ... o+trainers

richardjallen

Are fluid turbos much quieter? The thread suggests eventually they will leak. How do you repair them?

I was looking at the CycleOps Fluid2.

campagsarge

Not sure if you can get them serviced or not. Noisey? Well, I have mine set up in the back bedroom and if the GF is watching TV in the room below she says it sounds about as loud as a washing machine - the nieghbours say they cannot hear anything either.

Lagavulin

I had a budget of upto £200 but in the end opted for a Tacx 1435 Sirius Softgel and spent a few quid on Conti's Home Trainer tyre and Tacx's front wheel riser.

It's magnetic but I was quite suprised at how quiet it is. I had imagined it would be sort of washing machine/spin dryer loud but I certainly don't think its that bad.

Also, and perhaps most importantly (still living at home :roll:), my parents don't find it loud - though my mum has claimed anytime that Emmerdale is on is out of bounds.

Steve I

The Cycleops Magneto trainer is very quiet compared to others. From my own experience, I can definitely say it is a fair bit quieter and vibrates less than the Tacx Grand Excel I used to use. In any case, no matter how quiet the trainer itself is, there'll always be noise from the bike's drive chain.

I considered the fluid trainer but decided I didn't want to chance hydraulic fluid leaking in the house.

McBain_v1

Kurt Kinetic fluid trainer - I have one and it is fantastic.

richardjallen

The LBS was suggesting a Elite Chrono because it apparently flexes a bit and is better for carbon stays. Is there any merit in this? Could carbon stays be damaged in a turbo as they are unable to move?

SteveR_100Milers

It's as much a problem for a steel / ally frame. I'm not sure if you can generate enough force to snap the rear stays, but at least you will know for sure you have wrecked it! I use my carbon bike in a cyclops which doesnt give at all, and its fine so far, and I'm large and heavy at 92 kgs.

campagsarge

Yep, I was thinking the same the other night when I looked down and could see the stays and bottom bracket flexing.

richardjallen

SteveR_100Milers wrote:

It's as much a problem for a steel / ally frame. I'm not sure if you can generate enough force to snap the rear stays, but at least you will know for sure you have wrecked it! I use my carbon bike in a cyclops which doesnt give at all, and its fine so far, and I'm large and heavy at 92 kgs.

I guess a metallic frame once bent beyond its threshold will not return to it original shape. But neither will carbon after it cracks. The question then is which has the higher threshold.

SteveR_100Milers

richardjallen wrote:

SteveR_100Milers wrote:

It's as much a problem for a steel / ally frame. I'm not sure if you can generate enough force to snap the rear stays, but at least you will know for sure you have wrecked it! I use my carbon bike in a cyclops which doesnt give at all, and its fine so far, and I'm large and heavy at 92 kgs.

I guess a metallic frame once bent beyond its threshold will not return to it original shape. But neither will carbon after it cracks. The question then is which has the higher threshold.

Depends entirely on the design, but specific strength CF by some margin. Once a metal frame has plastically deformed (stays) its as useless as a snapped CF one. The big difference is CF doesnt fatigue, a metal frame will, whether it will do so faster in a turbo I don't know - some bright spark has probably modelled it somewhere (the reputable turbo manufacturers would have possibly done so).

redddraggon

SteveR_100Milers wrote:

The big difference is CF doesnt fatigue,

You sure?

There are loads of papers out there on CF fatigue.

richardjallen

So does anyone have an Elite Chronos? I noticed they have a rubberised roller rather than aluminium and its apparently quieter and does not go through tires as quickly.

richardjallen

redddraggon wrote:

SteveR_100Milers wrote:

The big difference is CF doesnt fatigue,

You sure?

There are loads of papers out there on CF fatigue.

What about de laminating under bending force?

SteveR_100Milers

redddraggon wrote:

SteveR_100Milers wrote:

The big difference is CF doesnt fatigue,

You sure?

There are loads of papers out there on CF fatigue.

I'd be interested to see them - its been 20 yrs since I did my materials engineering thing, but IIRC epoxy resins are amorphous and not crystalline in the way ally and steel is. It is impurities in the xtalline structure usually at grain boundaries that act as stress raisers, causing dislocation pile ups. These internal stresses cause micro cracking which leads to fatigue crack failure. Fatigue failure is a mode of failure caused by sub yield stress loading, and is not the same as ultimate tensile stress failure (which is how CF composites fail). This is admittedly pretty basic materials science I know...

It's the other main reason as a use for aerospoace applications, there are plenty of examples of fatigue failures in aluminium castings caused by poor impurity control during manufacturing that have led to some catastrophic events. Personally I prefer to fly in a plane with as much CF in it than one entirely fabricated from aluminium alloys, especially is Al-Li alloys are involved....

EDIT: a quick search reveals that CFRP's do fail through fatigue delamination. I can't find any info on what the relative stress levels are compared to aluminium (which is also affected by salt) wrt fatigue loading to UTS ratio. Nor can I find any simple anecdotal data on known failures apart from the airbus that crashed over New jersey in 2001 not long after 9/11, which was found to be due to excessive loading of the tailplane after several full rudder deflections (which exceeded the Ultimate Strength loading of the part). In other words, is it (CF) more or less susceptible to fatigue failure through delamination than metal frames are?