Carbon Frame Bike on Turbo Trainer?

gooner71

Hi guys,

Would I be putting a carbon frame under stress on a turbo trainer?

I've never had a turbo trainer before and only have the one road bike so a bit stuck if this is a bad idea.

Thanks
Simon

Wooliferkins

Slightly different stress yes. As your wheels on the turbo are fixed laterally the sideways moment of pedalling will be absorbed by the bike as opposed to turned into rocking of the bike (think side to side when honking) I would be surprised if it was quickly terminal but I would look for a hack frame for the turbo.

ut_och_cykla

The turbo trainer frame takes up the forces involved. A German bike mag did loads of tests (last year?) and concluded that your bike was more at risk doing mad bad sprints on the road than hard workouts on teh trianer. But if you're worried contact teh bike's manufacturer and ask them?

gooner71

Thanks guys - this question was posed mostly to find out whether I should be worried... lol. I might email Trek but what's the chance of a sensible answer on a 6 year old carbon frame?

tri-sexual

i use one, no problems
all the pros use turbos to warm up before races and tt

matterai

tri-sexual wrote:

all the pros use turbos to warm up before races and tt

I doubt they pay for their carbon bikes though

GavH

Sorry for the bump, but I'd be interested to hear from anyone who has had a CF frame fail on them due to use on a turbo. I've just been offered a very good price on my Carrera Virtuoso from a work colleague and this means I'll only have the Bianchi for both road and indoor use.

lloydy75

I've got a Tacx Flow with over 5000 miles logged and only used carbon frame road and TT bikes on it with no problems.

JohnnyAllez

Other option is a set of rollers with added resistance unit ? Lots more fun staying upright

chrisw12

Don't know the answer but I stay sensible on my turbo in that I try to keep things smooth and certainly don't stand up and certainly don't do power sprints.

I would have though that standing and rocking could cause damage due to the 'twisting force' you put in, can anyone confirm or deny this with some physics?

tri-sexual

i dont know why people are so scared of using carbon frames in " stress " situations
i have seen quality carbon frames undergo deflection tests you would not believe to be possible.
a carbon frame would be rigged up to a test machine with hydraulic rams continuously twisting the frame, the amount of force applied would be many times humanly possible and the amount of deflection is enormous, this sort of deflection would destroy a metal frame (alu, steel or Ti) in minutes but a good frame can be engineered to take these lateral forces and i have been informed that the frame would still be structurally sound even if the test is ran for over a year
i must stress that quality carbon frames were used so cant say for if this is true for all frames (dont blame me if your frame falls to bits)
there are videos on youtube where a carbon frame is crushed in a heavy workshop vice, the carbon can take alot of abuse before it delaminates and fails, a similar test is done on a aluminium frame from the same manufacturer and once the alu frame is crushed can never regain its original shape (cannondale)
other manufacturers do impact test where a heavy metal sphere is dropped from several feet onto a carbon frame, a good standard frame can withstand the damage but a super lightweight frame from the same manufacturer will be destroyed in the same test (these are the frames used in the mountain sections of the TdF)
commencal started doing carbon mtb frames this year, they say that its for strength rather than weight saving
cannondale scalple's rear stay is carbon and is designed to flex many thousands of times over a single bike ride and they seem to be structurally sound even after many years of use.
carbon frames can be engineered to be super stiff where required (aroung BB and head tube) and "flexible" in others (for comfort) in forks, seat stays, seat tubes towards the top, where some compliance qualities adds to the plushness of the ride.
not all carbon frames are created equal but a well deigned and engineered one can equal or exceed the specifications of any other frame material (excluding acid test, burn test, salt water tests which in many cases are pretty pointless anyway)
carbon and turbo trainers, i use mine even though i have bikes of other materials to choose from

chrisw12

I agree with what you're saying that cf as strong as anything and if well designed then no problems...

but what about my question as regards standing efforts? What I mean is, if you clamp the rear end then pull/push the bike over to the side (like you would when standing) then surely there will come a deflection point where the material will snap? Ok, you might not be able to generate enough force but doing this over and over, will it fatigue the frame?

I'm thinking for example when you snap the end of the opening part of a can, one part is fixed, but when you move the other end back and fore it eventually snaps.

I can't see how/why a frame would be designed for this as it's a totally different lateral force than the bike will experience on the road. When you 'stand' on the road the bottom of the tyre is the pivot point not the frame.

I ask this question about all frame materials not just cf by the way.

tri-sexual

all frame materials has a modulus of elasticity, simply put it will "give" to some degree (even glass will bend to some degree before it breaks)
fatigue occurs when a material fails after repeated bends and the structural integrity of the material fails
as i mentioned on an earlier post, seen a carbon frame tested where the front tube and the rear end is fixed to a test rig and the bottom bracket is subjected to forces where the bottom barcket is deflected laterally (by probably 150mm if not more) from side to side and the frame survived, the test engineer claimed that the frame can be subjected to such forces for a year without breaking
pro cyclists use cf frames on turbos (they probably dont buy their own), i use cf on turbos (i got choice of other frame materials to choose from)
i have broken a few frames (in all different materials) throughout the years -though most were due to impact damage, not saying cf will not break but a well designed and manufactured one can be much stronger than people think (some super lightweight frames will be weaker because less carbon plys and resin would be used)
personally i think they're fine for turbos-has anyone broken a carbon frame on a turbo? (not inc ones previously damaged from impacts/crashes)
for those who dont trust carbon on turbos, buy a cheap bike and use that instead- problem solved

GavH

tri-sexual wrote:

all frame materials has a modulus of elasticity, simply put it will "give" to some degree (even glass will bend to some degree before it breaks)
fatigue occurs when a material fails after repeated bends and the structural integrity of the material fails
as i mentioned on an earlier post, seen a carbon frame tested where the front tube and the rear end is fixed to a test rig and the bottom bracket is subjected to forces where the bottom barcket is deflected laterally (by probably 150mm if not more) from side to side and the frame survived, the test engineer claimed that the frame can be subjected to such forces for a year without breaking
pro cyclists use cf frames on turbos (they probably dont buy their own), i use cf on turbos (i got choice of other frame materials to choose from)
i have broken a few frames (in all different materials) throughout the years -though most were due to impact damage, not saying cf will not break but a well designed and manufactured one can be much stronger than people think (some super lightweight frames will be weaker because less carbon plys and resin would be used)
personally i think they're fine for turbos-has anyone broken a carbon frame on a turbo? (not inc ones previously damaged from impacts/crashes)
for those who dont trust carbon on turbos, buy a cheap bike and use that instead- problem solved

A good post and one that asks the million dollar question! Plenty of folks saying don't use one, but no-one has actually seen a frame break from use on a turbo, have they?

Monty Dog

From someone whose been on numerous cycling fora over the year, I have never seen anyone break a frame on a turbo - the question gets asked with regularity every winter.
What you will find is that many manufacturers say that turbo use invalidates any warranty - the same with using a roofrack too

Team Banana Spokesman

I would be worried about non-carbon bikes more because theyre weaker. if youve got carbon you should be able to push it harder than any other bike before permanently killing it.

GavH

I wonder if (BIG IF it seems) you did break the frame whilst on the turbo, whether or not your home contents insurance would cover it under Accidental Damage?

tri-sexual

i didnt know bike manufacturers didnt honour frame warranties if used on a turbo :shock:
if i did break any of my carbon frames on the turbo i am sure that i will be totally honest when asking for a replacement by telling them that it broke on a turbo trainer rather than through "normal" road use

The Mechanic

I have recently purchased a Felt Z4 full carbon bike. This is my first carbon frame and noted that the bike came with numerous stickers warning about just about everything, including "do not remove the sticker" warnings. It is interesting to note that one of the stickers said words to the effect that you should not clamp any part of the frame in a work stand, turbo trainer, roof rack etc.

monkimark

My turbo clamps the skewer, not the frame.

diamonddog

monkimark wrote:

My turbo clamps the skewer, not the frame.

^^+1 for this, I thought they all did.

ronaldperez

Ok so. Just purchased my first cf road bike. '13 Felt f5. Not going to lie was very scared until I read this forum. After hour or two reading I just figured jump on. So I did. No problem with flexing. Although I'm a super relaxed rider up top and very aggressive from the waist down I found no harsh flex. Can someone answer me this one? Since the front wheel is fixed and I now have a carbon steer tube, will this fixed position give me ridges in the tube? Or considering the frame is carbon fiber is that not a concern? My felt has MMC monocoque construction, stating it is incredible. Any thoughts on that? Thank you for your input. Any is appreciated.

Felt F5
SRAM force group set
Fulcrum racing wheels.