Scooter123

Hi Folks,

My wife of several years is considering a new bike. I'm encouraging her to consider carbon fiber. For medical reasons she can't deliver 100% power to the pedals. She's getting some help with this, but I think that an extra light bike would help even more.

I haven't been able to convince her of this yet. She's worried that CF will be too fragile and will scratch easily. She worries that it will become damaged if it falls over after being leaned on something outdoors.

I've read that CF is less resistant to some kinds of impacts than aluminum or steel, but (and as I write this I hear the accusation of trolling heading the other way) is this much of a concern?

One strike against is that she commutes, and needs to be able to bring stuff along. There isn't anything particularly heavy in her kit, but (like me) she tends to over-prepare. Some sort of pack or bag has to go on the bike. She uses a handlebar bag and an under-seat bag on her current bike, but would like to be able to have a pannier rack as an option.

As things stand we wind up off the back on group rides, particularly around hills. Some of the people we ride with are already riding CF. I think that losing some pounds off the bike would provide a significant advantage, making it worth the potential risk.

Assuming that we have all of the other bases covered (getting medical help [check], working off the holiday weight gain [mostly check], attempting not to overload the bike [constant struggle], etc)... Should I be more persuasive about CF? Is there any other downside to consider besides the obvious (added cost)?

Thanks for any pointers!

Scott C.

peckma

Consider this: even if your wife buys into the premise that CF is a durable, lightweight choice for her, if she is going to fret about it constantly you may be better off just getting her a steel or titanium bike.

I don't think CF scratches easier or is more fragile than metal bikes, other than perhaps a direct strike to the frame. A hammer, or car bumper, taken to a metal frame will ding or bend it, but fracture CF. But, in the event of a catastrophic blow to the frame, you'll probably replace it anyways. My Roubaix is CF, 2 1/2 years old with 10K miles or so on it, ridden over a variety of roads and the frame looks more or less like new, with some wear marks where the cables hit the headtube.

Suggest that she finds a bike that suits her needs of recreational riding and commuting that is in your budget, and pay less attention to the material that it is made of. Find a bike that makes her happy (happy wife happy life)

cplager

A couple comments:

(1) It's total weight that matters. Getting a light bike makes a much bigger difference to a light person than a heavy person.

(2) Weight matters for how quickly one can accelerate and for climbing hills. If there aren't hills (and your wife isn't racing), then light weight is less important.

(3) I don't know of any CF bikes that take racks.

(4) Peckma's right: Buy what makes her happy.

Cheers,
Charles

Lexi01

Wrong.

Wrong.

Wrong.

Seriously - when is this gonna stop? CF has been used on everything from bikes to planes for decades now. Everything fails at some point...but test after test shows that the breaking point of CF is WAY higher than aluminium frames.

Look at how the pros ride them...look at the beatng they take on Paris-Roubaix for example. If your wife gives her bike more punishment than Tom Boonen (who would no doubt also be heavier) I'd ve VERY surprised...and Tom's bike aint broke!

Let's get over the CF fears people...

Scooter123

I think that part of the problem is that I've been sticking with my 1990's steel Basso for recreational riding, despite the fact that its paint is starting to look ragged and it's been through a couple of sets of new components. I may have to make the sacrifice and start riding on CF myself in order to help sell the advantages...

Scott C.

cafzali

This is one of those "carbon myths." In fact, carbon fiber is the only bike frame material that can be reliably and safely repaired after a blow to the frame or other catastrophic accident that renders the frame unsafe. It helps if you're in/near a major market with shops that have access to qualified repair providers that actually do the work in house. But a carbon frame can actually be repaired to a stronger condition than it was before the accident. Keep in mind that a CF frame is just fiber strands and resin. If you use the proper materials, you can literally recreate a frame that was the same as before, if not stronger.

fietsbob

maybe the relationship can stand up to owning a Tandem, then efforts are combined rather than separated.



just thinking of classical fallacys of Logic: some one that rides a lot
and is off the front of the group,
they have a light carbon bike , so since they have a carbon fiber bike,
if I get one too, I will be just as Fast.. ..

A + B + C is =/= to that D .. in all cases ..


The engineers design for forseeable stresses of riding, .

but impacts at right angles to those normal stresses are not forseen..

hamster

I'm sorry, but this is completely false.

Yes, CF is fiber strands and resin. Fiber strands give it tensile strength and resin keeps them in place and gives it compressive strength.

Once the strands are broken, they are broken. There is no way to reconnect them. The best you can do is to put a patch on the hole using a new set of strands and new resin. It will bond to the old material, and it will look quite firm and sturdy, but you'll never reproduce the original strength. The bond between old and new resin won't be as strong as the original frame, it'll be even weaker than just cured resin without any carbon fiber reinforcement.

Ballpark numbers. Tensile strength of a typical carbon fiber composite: 200,000 to 300,000 psi. Tensile strength of high-end epoxy resin without reinforcement, cured as one piece: 12,000 psi. Tensile strength of a bond between fresh and cured epoxy (between the patch and the original frame): less than 2,000 psi.

TrailViewMount

Carbon fiber is hard and tough. Plus light equals better I believe. Ride farther for sure.

cafzali

You can quibble over stats, but the fact remains carbon fiber is a composite material and composites can be very easily and reliably repaired. Airliners are made of composites, albeit not carbon, and they're repaired and put back in service all the time with small airframe situations. Add to that, every major, respected carbon fiber repair shop in the U.S., such as Calfee, offers lifetime warranties on their work.

Some manufacturers, most notably Trek, go to great lengths to try and dissuade customers from repair, but that's because they want to sell you another frame, even if it's at a discount.

momsonherbike

Stop being persuasive - it isn't working. Obviously, she doesn't want a cf - hence, the laundry list of excuses. If you get one for her over her objections, she may use the same stockpile excuses to not ride it.

Why not simply ask her what she does want?

gcottay

+1

Your wife is right about the best bike for her. If CF were best for every other rider on earth she would still be right.

dbg

Even though I own a superlight CF bike, and even though it is my most responsive and fun ride, I would not consider using it for a loaded tour (obviously), a light tour (credit card and basic supplies), or commuting. I'm much more confident in the reliability and the potential failure modes of a steel frame. I have done "some" epoxy and CF repair work (not an expert) and would consider repairing a CF frame in the rear stays maybe. But I would never consider trying to repair damage to headtubes, maintubes, or BB areas. Too risky to do 40+mph descents on patched CF main tubes. Even new CF that has been bumped and banged around a lot --like my touring rigs frequently experience, would bother me a little.

aramis

Just get a cheaper aluminum frame if that's what she wants. If you get one with a carbon fork and stays they handle bumps great. The weight difference is probably about 1 pound so it will make no realistic difference in acceleration or speed. I would concentrate on something more important than the frame material, which would be the gearing. My carbon fuji SL1 weighs a little over 15 #'s and my aluminum road bike weighs over 18#'s. Even climbing 5000 feet or more in a day (and I'm even a skinny guy) I can't tell the difference unless the gearing is different between the two.

I would get lighter tires/tubes/wheels also if you are worried about weight as a pound there would be more important than a pound of weight in the frame.

It sounds like a triple or a compact with a 11-32 sprocket would be appropriate if there are any hills at all.

gyozadude

Yes, CF is very suitable for a recreational rider. And it can be strong. But it can also fail catastrophically and be unrepairable because a bike is a monocoque frame and unlike an airplane wing that is sectional (and also filled with high tech aluminum honeycomb that is 97% void and the bonding adhesive used on aircraft has slightly more rigorous testing done to it to ensure uniformity than the lay-ups they do in China). But that aside, recreationally, some folks ride slower. If the point is to push the SO to ride faster because you bought her a CF bike, think again. I ride steel. Been doing it for year. At my clyde weight the few pounds I shed on the frame a worthless. It isn't the reason I'm getting dusted on a ride or that most of the time, I dust someone else on a ride.

I commute by bike a lot. I use the short daily trips to train. I treat my rides to the next red light like time trials. On the other hand, my wife rarely ever gets on a bike. And my kids never ride that hard either. So when we do a 30 or 50 miler, for the wife - No Way! For the kids, they average like 13 mph if they're fast. For me on a vintage steel road bike, 18 mph is what I can do. It's the motor. Not the bike really.

Wooden Tiger

I don't wanna play the devil's advocate or stir the proverbial pot, but I own a carbon roadie and even though I know CF is strong, it still leaves me questioning its reliability. I just get real nervous every time I hit a bump between pavement cracks. While I've never had any bad experiences with my CF bike, I do sometimes wish I'd have gotten an aluminum or steel roadie instead.

Yes, I love the light weight and it makes for a great conversation piece, and yes, I enjoy the ease of climbing, but at the same time I'm just simply weary of the strength. If I could go back in time and repurchase my bike, I think I would have purchased a lightweight aluminum bike with really nice components instead of a carbon bike with okay components.

DX-MAN

A commuter/utility bike is not the place for 'altering a mindset', too much is on the line for the rider. In order to convince your lady that a CF bike is OK, she'd have to learn to trust it as a PLAYBIKE, the one she'd ride just for the fun/training miles -- not what I'm hearing from you about her riding.

I 2nd the motion -- get her what SHE wants. She's grown, and while you can ADVISE, you can't really EDUCATE unless she's receptive to it.