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  # 2252524 5-Jun-2019 22:01
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Batman:

 

 

 

Carbon bikes are stiffer than alloy and you might feel more bumps. But the way they build it is to make is absorb bumps.

 

 

I can see suspension will absorb bumps. But how they build the frame? You'll have to explain.

 

Remember any flex used to absorb bumps also makes the bike 'loose' and you waste energy extending and contracting the flex as you pedal.


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  # 2252525 5-Jun-2019 22:07
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elpenguino:

 

Batman:

 

 

 

Carbon bikes are stiffer than alloy and you might feel more bumps. But the way they build it is to make is absorb bumps.

 

 

I can see suspension will absorb bumps. But how they build the frame? You'll have to explain.

 

Remember any flex used to absorb bumps also makes the bike 'loose' and you waste energy extending and contracting the flex as you pedal.

 

 

It's proprietary. Trade secret.

 

Building a carbon bike is by hand all the way. You first design the carbon fabric. Specific to have a ratio of longitudinal strength vs width strength vs diagonal strength. You can build carbon fabric that is very strong lengthwise and very flexible diagonally and sideways for example. 

 

You then use each of these specifically designed fabric to build different areas of the bike. For example the top tube you want longitudinal strength but you want flexibility in the joints to move a bit to absorb the bumps. You design the fabric and lace it around your skeleton BY HAND. each and every strip. Hundreds if not thousands of strips. A bit like making newspaper meshe figurines.

 

Once you places the thousands of cuttings in place you cook it and then hand smooth it with some applied product and then cook it some more. Too little cooking and it will fall apart. Too much cooking and it will fall apart. THey cost more than a car to make. I would not buy a secondhand one unless I know that is has never been mistreated. And definitely don't buy cheap chinese clones.





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  # 2252530 5-Jun-2019 22:11
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what happens when carbon fails

 





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  # 2252531 5-Jun-2019 22:12
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Batman:

 

Mark:

 

My boys (both 11 and not that tall) are into triathlon and up to now we've been watching them struggle along with the wrong bikes for road use (maintain bikes), now they are eligible to enter proper races but have to have allowed bikes.

 

I'm looking for some pointers on lightweight road bikes that would be more suitable, not be stupid prices and fit in with the cycling nz rollout length rules and other rules (still wrapping my brain around that).

 

Any brands models I should be googling for ?  (and hopefully finding on Trademe for a pittance! :-)

 

 

I know nothing about kid road bikes.

 

But adult road bikes there are at least 6 types.

 

For your child I would recommend getting an alloy road bike that is the CORRECT SIZE. THat should make all the difference.

 

 

That's good advice - and with their size changing over the next few years you may not want to pump too much money in a youth sized bike.

 

All the major brands would be fine. As far as componentry goes I haven't used anything but Shimano but I assume the other brands are ok since they haven't gone out of business.

 

The difference in weight between alloy and carbon bikes is small and if 1-2 extra kilos is holding you back then by all means splash the cash.


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  # 2252532 5-Jun-2019 22:12
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this guy is a professional and uses professional grade one piece carbon handlebar - and it failed

 





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  # 2252579 5-Jun-2019 22:22
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carbon vs alloy. in riding stress, ie put some heavy bloke on it, carbon is stronger in that specific force vector. this is a mountain bike, so the specific force includes put a heavy bloke on it and jump all over the bike. does not include the force of slamming into a tree - very different force vectors.

 

road bikes are designed to be less hardcore, this frame in the video looks like a santa cruz nomad 2014 - i checked the frame weight is it 2.8kg. a road bike frame weighs less than 1kg. wayy less material and hence strength. riding over road bumps will introduce fatigue to the point of failure, but it will take many many years.

 





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  # 2252724 6-Jun-2019 05:42
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@batman miles off topic dude.


 
 
 
 


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  # 2252726 6-Jun-2019 06:34
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Mark:

 

My boys (both 11 and not that tall) are into triathlon and up to now we've been watching them struggle along with the wrong bikes for road use (maintain bikes), now they are eligible to enter proper races but have to have allowed bikes.

 

I'm looking for some pointers on lightweight road bikes that would be more suitable, not be stupid prices and fit in with the cycling nz rollout length rules and other rules (still wrapping my brain around that).

 

Any brands models I should be googling for ?  (and hopefully finding on Trademe for a pittance! :-)

 

 

don't know if you kids are too tall for this bike but they are made for smaller hands and shorter fingers

 

but from looking the build i'd say they are the bottom of the range type road bike, and not the fastest or easiest out there. brakes may or may not be reliable. seat may be too padded and your butt-thigh interface might swell up. too few gears so the jump between gear shift might be too wide to pedal efficiently. gear shift may not be even reliable. but it's cheap. expect to pay circa 3-5k for something that does not have any of the issues i mentioned. but the least you can do if you buy this bike is get a proper saddle.

 

last thing when you ride a road bike in the wet i suggest you practice the course because it is very easy to slip and fall riding in a straight line, let alone turning corners. there is a very specific way to turn corners and not end up with a broken arm. in a road bike, wet does not mean thunderstorm. morning dew or dew from morning at 12pm in a shaded area (as many corners could be) is considered wet. uphill corners are fine. but a proper triathlon track should have very few of these.

 

https://www.evolutioncycles.co.nz/Product/268319/2019-giant-tcr-espoir-24-grass-green

 

 





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  # 2252729 6-Jun-2019 07:05
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had a look for a better youth road bike - apparently they don't necessarily exist. that giant seems to be as good as builds get.

 

here's a crash

 

falling going straight (ish) at 22s 

 

 

 





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  # 2252734 6-Jun-2019 07:24
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this may or may not go as fast but is likely easier to control and probably a lot more expensive


https://www.scott-sports.com/nz/en/product/scott-gravel-24-bike?article=270058043





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