The mystery of the damaged down tubes

[Jules]

Spinnekop now I know why you sold me your cages

 

 

 

 

 

[Jules]

Update: took my bike to Macarbi, the carbon repair specialists, and they say the carbon has been weakened there. A patch was recommended.

 

 

 

The cynics might say that's like asking a hairdresser whether you need a haircut, but I reckon it's better to be safe than sorry, so I'm having the patch done.

 

 

 

Will post pics once it's done.

[Mudsimus]

Better safe than sorry. Will it be a wrap around patch or just a spot patch?

[Jules]

Wrap around. Apparently that's the best way to strengthen the tube.

[Christie]

I don't think a patch is neccesary.

 

The scuff mark is not in an area of high stress on the frame. High stress areas are were the tubes are joined. Imo all that is needed is a bit of epoxy and re-polish.

 

I'm pretty sure the wrap around CF patch won't match the pattern of the original weave perfectly, and be noticable as a bump on the frame. You might end up paying for some cycleart repainting, too.

 

Some questions to ask them:

Will they be using the same 12k (12000 strands per bundle) cloth as the original?? (or at least, I think they use 12k cloth on the newer Scotts)

 

What grade of fiber will they use? Im pretty sure the Scott is made from a high modulus fiber. A repair with standard modulus material like T300 won't strengthen the frame that much. The thing is, high modulus fiber is expensive, and they will have to buy a whole roll of cloth. Manufacturers in the aerospace sector complain about the cost of a roll of HM cloth, so I doubt if smaller companies will have some standing in the corner.

    

Christie2010-02-01 12:00:40

[epoh]

I decided to leave my bike as is with the little ding... thinking of buying a new biking anyways.

[SwissVan]

Wrap around. Apparently that's the best way to strengthen the tube.

 

If they were really brave and knew whats what they would do a plug type patch....which would involve making a nice hole in your downtube...

 

ok i'm just kidding.

 

Looking at the pictures Barend posted it makes sense now

 

Repairing it is probably a bit overkillish but at least (hopefully) there will be no sign of any damage / patch afterwards. Will be interesting to see the end result.

 

 

[Edition 507]

I hope they are quite snappy about it! Oops, wrong choice of words. I hope they prioritize the job in good time for the Herald this week-end

[Jules]

After reading Christie's response, I'm starting to feel like a bit of a woosie. However, the thought of a Cycle Art job is appealing...

[Jules]

I hope they are quite snappy about it! Oops' date=' wrong choice of words. I hope they prioritize the job in good time for the Herald this week-end [/quote']

 

 

 

Carbonboy, I hope so, otherwise I'll be doing the race on a steel Colnago with down tube shifters

 

 

 

Christie, put your comments to Macarbi, and their response is below.

 

 

 

I'm posting this to give some insight to anyone else who is contemplating a carbon repair. These guys seem quite jacked, and are keen to branch out into the cycling market.

 

 

 

The posting you received does make sense in that the damaged area was not caused from a high stress situation, however that does not negate the fact that the frame has been weakened in that area, and thus could potentially become a break area under strain (remember, many frames break when bumped or crashed, and in these cases they break in their weaker areas). We often do repairs in areas other than at tube joins (as otherwise suggested by the post below), so frames do break wherever there is a weakened area. I have attached pics of such repair areas. (By the way, a bit of epoxy and re-polish will practically add no strength at all, it will just seal it and smooth it ? I?m sure whoever sent the info below will know that epoxy needs material to add sufficient strength).

 

 

 

We often use UD carbon to give directional strength, and then sleeve it with 200gram 3k carbon cloth, which (correctly mentioned below) is not the same weave as your frame, but is still incredibly strong.

 

 

 

We repair rowing oars and top-end racing boats (all carbon epoxy repairs), and one thing is certain, a rowing oar comes under a lot more strain that a bicycle frame (a rower is using his legs, back and arms to exert as much force as possible through an oar when racing). We never have a repeat break on a repaired area.

 

 

 

Yes, if the repair is left unpainted, then it is noticeable, but we do align it with the run of the tube. There are various contacts who can re-spray the repaired area.

 

 

 

Finally, we actually do keep stocks of carbon, as we are the biggest rowing equipment supply and repair business in SA, and we have been working with these materials for over 10 years.

 

 

 

 

 

 

 

 

 

 

[Jules]

Here are the pics he mentioned:

 

 

 

http://photos-g.ak.fbcdn.net/hphotos-ak-snc3/hs218.snc3/22571_471715970640_868120640_10801102_4421612_n.jpg

 

 

 

http://photos-a.ak.fbcdn.net/hphotos-ak-snc3/hs218.snc3/22571_471715985640_868120640_10801103_395132_n.jpg

 

 

 

http://photos-d.ak.fbcdn.net/hphotos-ak-snc3/hs238.snc3/22571_471715990640_868120640_10801104_7899286_n.jpg

[AndreZA]

And there goes the big weave pattern n the bike. Maybe it's a good time to send it for a new paint job. Put some fake Cannondale stickers on to match your new team.

[Mutt]

The response you received is extremely positive and, in my opinion, is inviting customers. It says something about them that they were prepared to supply such an in depth answer.

[Jules]

And there goes the big weave pattern n the bike. Maybe it's a good time to send it for a new paint job. Put some fake Cannondale stickers on to match your new team.

 

 

 

Carbon fibre - it's all nonsense! I'm not a ponce, I don't mind a bit of a change in the weave pattern

 

 

 

 

[Edition 507]

Put some fake Cannondale stickers on to match your new team.

 

Don't put fake Cannondale stickers on, put then real thing on and dramatically increase the resale value of your bike

[GoLefty!!]

I don't think a patch is neccesary.

 

The scuff mark is not in an area of high stress on the frame. High stress areas are were the tubes are joined. Imo all that is needed is a bit of epoxy and re-polish.

 

I'm pretty sure the wrap around CF patch won't match the pattern of the original weave perfectly' date=' and be noticable as a bump on the frame. You might end up paying for some cycleart repainting, too.

 

Some questions to ask them:

Will they be using the same 12k (12000 strands per bundle) cloth as the original?? (or at least, I think they use 12k cloth on the newer Scotts)

 

What grade of fiber will they use? Im pretty sure the Scott is made from a high modulus fiber. A repair with standard modulus material like T300 won't strengthen the frame that much. The thing is, high modulus fiber is expensive, and they will have to buy a whole roll of cloth. Manufacturers in the aerospace sector complain about the cost of a roll of HM cloth, so I doubt if smaller companies will have some standing in the corner.

    

[/quote']

 

 

Sorry Christie, your view here is not entirely correct .

 

On many frames the areas of high stress is where the lugs join the tubes and in many carbon frames this is the same area where the seat tube water bottle will impact the downtube.

 

There is a lot of stree going through the lower junction of the frame and in particular the bottom area of the downtube and near the head tube junctions.

 

Delamination in this area will result in further delamination and the tube could fail.

 

A patch would certainly help recopver some strength and god knows how thin these carbon things are these days that very little damage becomes a massive problem later on.

 

Another aspect to consider is if the frame does fail, the manufacturer will not honour the warranty due to user abuse.

In any case of carbon damage, its best to get a repair done despite losing the warranty.