At 140 kg (22 stone), am I too heavy for a carbon frame?

jeffwode

I'm considering trading up from my specialized hybrid to a full spec. road bike and I'm seriously considering this bike from Planet X . http://www.planet-x-bikes.co.uk/i/q/...arbon-sram-red

My question is this.

At 140 kg, am I too heavy for a carbon frame? Are carbon frames still prone to breaking under stress or is this a problem that was common some years ago but has been addressed by better technology and better frames? Planet X says it'll take my weight. I'd love to hear what you think.

I know I'm going to have to get better wheels than the ones included in the offer but will the frame hold my weight for fitness / training? I cycle at an average of 27 - 28 kph and have hit up to 69 kph on fast descents. I'm steadily losing nearly a kilo a week and my target weight is 115 kg. I'm always going to be a big guy, I'm a former GAA mid-fielder and rugby number 8.

Would appreciate the opinions of this forum. I've learned a lot here already. Thanks

Chips Lovell

No, you won't break it. Good sturdy wheels are a good idea as you'll give them more punishment than a lighter rider would.

Lumen

What size tyres are you running on your hybrid, and what pressure are you using?

RobFowl

Laurence Dallaglio ride a carbon fibre Giant on that long distance ride to all the rugby stadiums earlier this year and hes 18 stone so you should be fine. I'd just check to see if the manufacturers have a weight restriction (some do list it) and go for a more robust frame and not s=one of the super light weight ones out there.

+1 of a decent wheel-set

jeffwode

Lumen wrote: »

What size tyres are you running on your hybrid, and what pressure are you using?

I have 26 inch wheels with (I think 35mm) Schwalbe road tyres. It's actually a MTB but with no suspension. I keep the pressure above 80psi most of the time. I've been doing around 100 - 150 km per week this past few months and I'm keen to move to a proper road bike now.

Lumen

jeffwode wrote: »

I have 26 inch wheels with (I think 35mm) Schwalbe road tyres. It's actually a MTB but with no suspension. I keep the pressure above 80psi most of the time. I've been doing around 100 - 150 km per week this past few months and I'm keen to move to a proper road bike now.

OK. Here's a tyre pressure calculator.

For total bike+rider weight of 320lbs, it recommends 135/207psi front/rear. That's not going to work.

For 28mm front and rear it gives a more sensible 96/146psi. You could probably get away with 130psi on the rear.

You'll need proper 28mm tyres though. My Ultremo 28s are only just over 26mm wide at 80psi, although maybe at 130psi they would stretch to spec.

There are caveats on that calculator, referencing here.

Anyway, I'd probably go for something that can definitely take a proper 28mm tyre at full inflation, which may rule out a Planet-X (the Nano, although the Pro may be OK).

jeffwode

That's a useful calculator Lumen. Thanks. I had been thinking of 25mm tyres, maybe I should revise that upwards to 28.

ednwireland

when i bought my focus cayo they said the weight limit was 120kg

look keo 2 pedals have a weight limit of 100kg

CheGuedara

+1 on what's been said before.

Re. the wheels - when you're ordering you can 'customise' what you're selecting, one option of which is the wheels.

The default selection are Planet X's own model B wheelset which is 24/20 spoked, you could change this to their model B wheelset at no cost which is 32/32 spoked which would be that bit sturdier due to their higher spoke count. So there's a freebie tweak to get the bike right for you right from the get go

kumate_champ07

I would go with 36 front and rear. mavic have a319 rim available in 40h but getting a hub might be a problem, 40h would be nice for the rear.

4 extra spokes do make a difference

DualFrontDiscs

Forum for 'heavier' riders here http://www.bikeforums.net/forumdisplay.php?248-Clydesdales-Athenas-(200-lb-91-kg)

+1 on 36 spokes.

DFD.

jeffwode

Thanks for all your replies. It's great to get some practical advice from people with direct experience. I'm much happier now. I'm going to measure myself in great detail over the weekend and order the bike. Yay!. I'm planning on using this fit calculator, http://www.competitivecyclist.com/za...LCULATOR_INTRO unless anyone here has a better suggestion?

Lumen

jeffwode wrote: »

Thanks for all your replies. It's great to get some practical advice from people with direct experience. I'm much happier now. I'm going to measure myself in great detail over the weekend and order the bike. Yay!. I'm planning on using this fit calculator, http://www.competitivecyclist.com/za...LCULATOR_INTRO unless anyone here has a better suggestion?

I've used that calculator before, didn't find it very easy or accurate. It recommended a top tube + stem length of around 640mm-660mm.

I currently ride with a top tube + stem length of about 690mm.

I am unusually stretched out, but that 30-50mm is a massive difference.

The Dave Moulton chart recommends tt+stem of 665-685mm based on inseam and height, which is much closer to my fit.

If you're buying online, I'd suggest you go by the manufacturers size chart. If that place you around the middle of a size, happy days. If you're between sizes you'll need to decide whether to go smaller or larger which can be a bit of a difficult decision.

If you're buying in person from a shop you should get fitted properly on the bike. An experience fitter will be able to ask all the right questions and get you set up pretty bang on right away.

ednwireland

jeffwode wrote: »

Thanks for all your replies. It's great to get some practical advice from people with direct experience. I'm much happier now. I'm going to measure myself in great detail over the weekend and order the bike. Yay!. I'm planning on using this fit calculator, http://www.competitivecyclist.com/za...LCULATOR_INTRO unless anyone here has a better suggestion?

i went through those fit calculators and it doesnt really match what i like riding (if you buy from wiggle email them with your height and inside leg and they'll give you an idea of what you need,

same with most of the online sellers i think (apart from possibly chain reaction)

as to 36 spoke wheels i managed to bust a spoke on my commuter (36 spoke rear hand built ) but my rs 10 simano wheels are a year old now .... go figure

peterako

RobFowl wrote: »

Laurence Dallaglio ride a carbon fibre Giant on that long distance ride to all the rugby stadiums earlier this year and hes 18 stone so you should be fine. I'd just check to see if the manufacturers have a weight restriction (some do list it) and go for a more robust frame and not s=one of the super light weight ones out there.

+1 of a decent wheel-set

18 Stone (114kg) is a LOT less than 140kg

Another plus on the wheel-set.

I thought Carbon Frames were supposed to be super strong....(says this lightweight at 100kg on his alu frame )

Lumen

peterako wrote: »

I thought Carbon Frames were supposed to be super strong....(says this lightweight at 100kg on his alu frame )

Carbon fibre is just like any other material - the strength of the product depends on how it is used, and how much of it is used.

As I posted in the other thread, CF products don't have to be weak.

I've seen a few reports of cracked CF chainstays on several high end brands. This is presumably down to production defects, underbuilding the frame to hit a weight target, or an attempt to introduce compliance in the frame using skinny tubing.

As others have suggested, check out weight limits on any bikes you are considering. Planet-X would definitely not be my first choice at that weight, maybe something more mainstream like a Giant which sells in the millions and is likely to have good local dealer support.

edit: although I've heard that some of the wheels that come on entry-level Giants are a bit weak. You might consider building something up from a frameset and components. I have a Scott frame that's survived one 40kph crash without a scratch, although I'm a lot lighter.

Donie75

Hi,
I did a few years at a similar weight on a hybrid and I bought a road bike in May. I was around 21st when I bought the Specialized Secteur Elite. I cannot fault the bike one bit. The geometry is really good for me and the higher front makes it easier on long spins. The only issue I had was the Mavic CXP22 wheelset. After a few weeks I had a slight buckle and a few loose spokes. My LBS sorted it but advice on boards said that I should ask to get the spokes glues with some threadlock. The bike mechanic was reluctant but after a few return visits to the LBS he agreed to use threadlock and I haven't had a problem since. I know the secteur is not full carbon but it's a great bike for a big fella.