Frames

Questions about purchasing bicycles and parts

Frames

Postby wombatoutofhell » Tue Apr 24, 2007 7:32 pm

Ok-I've been looking at bikes now and pretty much have the quality of components sorted out in my head and what level i want-but frames have me stumped. I don't really want to start a debate, but what frame materials (cro mo, alloy, carbon, titanium etc)have what characteristics? I know some frames are more rigid than others and some are more shock absorbing-but is it enough to really notice when you're riding? Is 2 kilos difference in weight noticable? whats stongest? Anything else I should know?
I know my budget doesn't extend to carbon fibre, but if it's worth it i may put off buying for a bit and save some cash for it.
I should mention I'm talking about a road bike here-but MTB people I'm curious about your opinions too.
Also is a mix desirable? like alloy frame but CF chainstays and/or forks? I've seen some frames with an alloy head tube intergrated with a c/f down tube. Whats the idea of this sort of thing?
and finally-whats the difference between 7005 and 6061 alloys-and are there more?
thanks experts!
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by BNA » Tue Apr 24, 2007 8:13 pm

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Postby MountGower » Tue Apr 24, 2007 8:13 pm

G'day
Last edited by MountGower on Mon Mar 23, 2009 2:23 pm, edited 1 time in total.
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Postby Bnej » Tue Apr 24, 2007 8:29 pm

Steel alloys are springy, allow smaller tubes, can be very good but depends on the type. e.g, K-Mart bike steel is not the same as Trek 520 steel. Steel bikes are great for tourers, and good quality cro-mo frames are not much heavier than their aluminium counterparts.

Aluminium requires more material than steel for the same strength, is more rigid (transmits bumps), but can be lighter. Alloy forks are a terrible idea, the shocks go straight up your wrists.

Carbon fibre can be light, can be strong, and can be shaped to suit the requirements of each part - i.e, thin vertical fat horizontal to allow flex in only one direction. It does a great job of absorbing vibration, and is very nice to ride compared to aluminium. Generally a CF bike won't allow things like racks, as the material is vulnerable to being crushed if a lot of force is applied at a small point - e.g, over-tightening bolts.

CF forks are a good idea, they smooth out the tiny bumps on normal road surface so your hands aren't getting buzzed constantly. A full CF frame does reduce vibration from the road coming through the pedals. It's noticeable. I presume CF stays would have similar benefit.

Synopsis:
Alloy frame and CF fork if you want a fast bike on a budget, or if you want to fit a rear rack and be semi-practical.

Alloy frame with CF fork & stays if you want a bit more vibration damping and won't need a rear rack.

All CF if you want a fast comfortable bike with some bling.

Steel frame if you want a practical bike, or a tourer.

AND
Is 2 kilos difference noticable? Pick up a 2L bottle of milk, and run around the block. Did you notice it? ;)

Seriously, I dropped about 5 or 6 kg in weight between riding with a hybrid and an OCR C3, it's astonishing. I weigh about 65kgs, and with the OCR I can push a higher gear up hills with less effort, and my average speed went up by 3-5km/h depending on the route. I'm doing 100+ km weekends where before it'd be a struggle to do 50.

2kg is not such a huge difference but you will certainly notice it.
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Postby Bnej » Tue Apr 24, 2007 8:34 pm

MountGower wrote:Carbon fibre is OK if you want to save 0.2 secs to get a Gold medal instead of a silver one. For the average rider it is bad value for money and not really more than a gimmick. Not very crash proof either.


Well, I've seen a alu. bike with CF forks that had been crashed, frame bent nearly 90 degrees like a crushed coke can, CF fork no worse for wear. Any bike frame you crash hard enough to break CF is going to be written off.

There's differences between racing CF frames, which are light and load limited, and OCR like CF frames, which have lifetime warranties and are built for strength.

Might only save you half a kg, but boy it's nice to ride.
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Postby LuckyPierre » Tue Apr 24, 2007 9:11 pm

I like my girlie bike (aluminium frame, carbon forks).
I'd like an Orca or a Damocles (carbon).
But, all together now: "Steel is real!"
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Postby sogood » Tue Apr 24, 2007 10:30 pm

MountGower wrote:Carbon fibre is OK if you want to save 0.2 secs to get a Gold medal instead of a silver one. For the average rider it is bad value for money and not really more than a gimmick. Not very crash proof either.

Don't discount CF as its price is coming down quickly and more and more mid-level frames are now full CF. It won't be long before it filters down to lower part of the range.

In terms of crash proofness, Alu isn't much better. It all comes down to luck.

At the end of the day, there are superfantastic steel frames as well as superfantastic Alu, Ti and CF frames. They are just the material and it depends on how they get used by the designer, engineer and manufacturer.
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Postby sogood » Tue Apr 24, 2007 10:33 pm

LuckyPierre wrote:But, all together now: "Steel is real!"

So what's metaphysical? :roll:
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Postby heavymetal » Tue Apr 24, 2007 11:14 pm

Steer clear of paper mache frames. I just broke my test one. :D Bamboo is quite strong and has a bit of flex.

I ride a tourer that is an aluminium frame with a cromoly fork. Coming from previous steel framed bikes (my preference), I have found that this bike is a better ride when loaded as there is less flex in the frame. I'm actually starting to prefer this bike.

I've had several alloy framed bikes and don't like the flex in the frame.

I know nothing about carbon fibre or titanium so I can't comment on those.

I've always prefered steel due to the fact that any garden variety welder can make emergency repairs.
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Postby wombatoutofhell » Tue Apr 24, 2007 11:23 pm

thanks for the replies all-gives me a little to think about. The problem is i have only ridden steel bikes-the best being a Ricardo road bike in the mid 80's. So I am well behind the times and have very little idea on modern technology. Learning fast though.
The bike i was planning on buying was the Fuji Tourer (Steel)-seemed to be the right bike for what I want. However, as Goldcross wont allow a test ride, i wont allow myself to buy from them-and they are the only stockists in Melbourne. Hence why I'm asking about other frames.
MountGower suggested a second hand frame with modern components-do the old 27" road bike frames fit modern 700c wheels?
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Postby stryker84 » Tue Apr 24, 2007 11:34 pm

[hijack][rant]
Personally I've found all of the GoldCross stores I've meandered into to be not very helpful at all.
Either I've been ignored (probably was passed off as "cheapo uni student who can't afford to be worth their while") or not tried to actually find out what I'm actually looking for and help me with it.
And even after they found out I WAS interested, they didn't offer me a test ride of anything, with a flat refusal from most if I asked for one. Most other shops, as soon as I pointed out a bike, it was "would you like to take it for a spin?" even if it was just round the parking lot.
Side note: This really didn't impress me. I had gotten a couple of blocks from home, realised I forgot my hardhat, and popped in to loan a helmet to ride back and pick mine up, offered to leave my drivers licence as security like you would if testriding. Was flat refused with "No, we don't loan out helmets." "What about for test rides?" "Nope, we don't do them here."
A shop with such low quality service will never get my $$. Not impressed, GoldCross.
[/rant][/hijack]
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Postby europa » Tue Apr 24, 2007 11:43 pm

wombatoutofhell wrote:MountGower suggested a second hand frame with modern components-do the old 27" road bike frames fit modern 700c wheels?


Not easily.

Modern gearing is much wider physically than the old five and six gear setups, so the rear wheel has gone from 126mm wide to 135mm. You have to have the rear triangle of your bike reset to take the wider wheel - it can be done and can be done yourself, but you can also ruin a good frame so taking it to a frame builder is the safest bet.

The next issue is the brakes. Modern brakes don't adapt easily to an old frame as they lack the reach. This can compensated for with brackets, but that's just something else to make - for example, the Shimano600 brakes going on the Europa will need a bracket that places the pivot bolt of the new brakes below the metal of the fork :shock: It gets worse when you go to 700c wheels which, although nominally larger at 28", are in reality smaller, thus making the brake reach issue worse. Of course, you can take your old frame to a frame rebuilder and have him braze in new brake mounts and this is the best solution.

Then there is the cost of new componentry - you'll find yourself spending more than a new bike with a full tiagra groupset very quickly and probably up around the price of bikes with a 105 groupset. I know this because I priced doing it to my Europa.

It's doable and in some cases, sensible, but you have to really like the old frame to make it worth it. You can make savings on components by buying cunning over the internet, but the reality is that you aren't going to save a hell of a lot.

If you are in love with the old frame and it suits you perfectly, do it. If not, buy a new bike ... then convert the old girl to a fixie :D (hey, it worked for me)

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Postby wombatoutofhell » Tue Apr 24, 2007 11:55 pm

sounds like my experience as well stryker-i had a guy come and talk to me who instantly tried to steer me to a bike other than what i was interested in. Nice bike i admit but not what i wanted or can afford. But no test rides means no business from me!
europa, I'm not in love with my old frame-just looking at options. Only had my bike a few weeks-the story is over in the retro thread. sounds too hard to convert the old malvern-i think I'll keep it for running to the shops (no one's likely to steal it-and if they did it's no great loss) and get a new bike for commuting to work and weekend rides. Alloy seems to be the easiest and cheapest to get-once someone tells me the difference between 7005 and 6061. At the moment I think i like the shogun samurai-7005 alloy, carbon fork, 105 shifters and deraileurs, about $1000 to $1100 price-just need to ride one.
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Postby Mulger bill » Tue Apr 24, 2007 11:57 pm

G'Day Wombat

From the MTB perspective. :wink:

Good Steel is a little heavier than comparable Al but has a livelier feel, (if you know what I mean) and does a great job of taking the sting from a hardtail, but is not suited to duallies unless heavy gauge stuff is used, basically DH only.

Al is beer cans, common as muck, but as Mount Gower said, It's hard to find factory Steel at a price I can afford :x Al is pretty easy and cheap to mass produce once the tooling's done.

Ti supposedly combines the ride of Steel with the weight of Al, the price of gold and the look of Heaven.

Carbon? The seatpost and fork of my roadie are made from it... :oops:
It's use in MTB is increasing.

Merida was making Magnesium frames at one stage, but they burst into flames when crashed :shock: Naaah, Mag is popular for suspension fork sliders.

Shaun
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Postby MountGower » Wed Apr 25, 2007 8:18 am

Mulger
Last edited by MountGower on Mon Mar 23, 2009 2:23 pm, edited 1 time in total.
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Postby wombatoutofhell » Wed Apr 25, 2007 1:26 pm

MountGower wrote:wombatoutofhell wrote:
MountGower suggested a second hand frame with modern components-do the old 27" road bike frames fit modern 700c wheels?
As for finding an old frame and putting new components on, I meant a 90s frame not something so old it needs mods to accomodate the new gear.

I have no idea when 700c bikes came in-i only found out they existed a couple of months ago when I started looking. As far as i knew 27" was still the norm. Like I said I'm hoplessly out of date!
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Postby mikesbytes » Wed Apr 25, 2007 4:22 pm

Each frame material has its own characteristics. Its how well the frame designer has catered for the characteristics of the material that makes it a good frame or a bad frame.

Rather than restricting yourself to a particular material, I'd be considering your fit to the bike, the cost, the comfort, the performance, durability, etc etc.

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