Road bike recommendations

thanks for the replies,
the trouble is that for someone without any experience is hard to tell what measurment will make difference looking just at the geometry chart
on some 55cm bikes i tried 55cm tt was ok, on some other felt way too long...
The shops usually stock one size of each model so it's sometimes impossible to compare different sizes straight away

i think that i'll need to get a proper fit before buying a bike

btw, does anyone know which london shop stocks colnago's apart from sigma and evans?

Ribble's 7005SL (sloping top tube) geo chart is doing my head in.

http://www.ribblecycles.co.uk/assets/images/FrameGeometrySloping.gif

Is there any way to calculate the effective top tube from that?

Ribble's 7005SL (sloping top tube) geo chart is doing my head in.

http://www.ribblecycles.co.uk/assets/images/FrameGeometrySloping.gif

Is there any way to calculate the effective top tube from that?

Is'nt it just B2
Reach = B2 - C2

Is'nt it just B2
Reach = B2 - C2

this

sorry but.... DUH...

I guess, though the diagram sort of shows B2 ending at the actual seat tube / top tube joint, not higher and further back which is where it would join if the top tube were horizontal. OK guess I can't do geometry.

The diagrams for their other frames are more explicit about the difference: example

I guess, though the diagram sort of shows B2 ending at the actual seat tube / top tube joint, not higher and further back which is where it would join if the top tube were horizontal. OK guess I can't do geometry.

+1.

I think the original question was a fair one. My guess is that the actual effective top tube length = "B2 plus a little bit", which is not really covered by any of the letters in the diagram.

...
i think that i'll need to get a proper fit before buying a bike...

http://www.lfgss.com/thread60484.html

that's how all frame geom is given. How the hell is the manufacturer supposed to know where you'll have your saddle on the rails / where your hips will be?

By extending the seat tube until it meets a horizontal line from the top tube / head tube joint. No?

Bugger it. I'll measure my frame with a ruler. Can't make head or tail of those figures.

that's how all frame geom is given. How the hell is the manufacturer supposed to know where you'll have your saddle on the rails / where your hips will be?

If you draw a horizontal line from the red dot that's at the top of the head tube, back to the centre of the seat tube, that would be the effective top tube length. (Note this is the "little bit" more than B2. That measure is a fixed property of the frame geo (assuming your front and rear wheels are the same size!), so independent of seat set-up, etc.

Surprising how many 'sportive' versions of frames are a no-go as 1small spacer and a flipped stem are still too high for me.

This is very common for us shorties. Fit wise, my roadie is'nt set-up for anything other than comfort. Yet, I have a reputedly 'agressive' frame with only 8mm of spacers (might go down to 1/2cm, still tweaking things). A lot of modern road frames would require inverse headset spacers to fit me.

If anyone cares, the math seems to work out after all:
(A2 - C2/cos(a)) * cos(a) + B2 = virtual horizontal TT length
(chart)

Assuming A2 is the BB to virtual top length and B2 ends at the actual TT/ST joint that gives
A2 = 52 cm Effective TT = 54.1 cm
A2 = 54 cm Effective TT = 55.6 cm
etc

OK. B2 + 14-16mm

If you draw a horizontal line from the red dot that's at the top of the head tube, back to the centre of the seat tube, that would be the effective top tube length. (Note this is the "little bit" more than B2. That measure is a fixed property of the frame geo (assuming your front and rear wheels are the same size!), so independent of seat set-up, etc.

It is'nt truly independant of seat set-up though. This is the problem, and why Tester mentioned Reach, as a better measure. Your saddle should always be the same distance behind the BB (the old plumb line from knee thing). This is achieved by a combination of set-back, and the angle of the seat tube. The trouble with ETT is that it is only effected by the STA, without taking into account set-back. So you can be misled.

So you buy an aggressive frame with a 74.5 STA, with your perfect ETT of 53cm. Place your saddle on it, pushing it back say 1.5cm more than usual because of the steep STA, and bang. Your reach is 1.5cms more than the ETT hinted at.

You dont need to do the trig. Just be aware when using ETT, and quickly check the seat tube angle.

Annoyingly, rarely stated.

that's fine if you know what they mean and how to interpret them, a lot of people don't

It's starting to appear on more geometry charts, with any luck it will catch on fully and young people will eventually wonder what us old folk are on about when we talk about seat tube angle - a largely meaningless number with curved tubes which don't line up with the centre of the BB shell on modern carbon frames, and optional ISP toppers which change the effective STA by a couple of degrees.

I'm ready to buy my first road bike and i have decided to buy canyon.
I wanted ultimate al 9.0 https://www.canyon.com/_uk/roadbikes/bike.html?b=2505 but it won't be available until march 2012.
The carbon version is available now https://www.canyon.com/_uk/roadbikes/bike.html?b=2508 it's obviously mor expensive.
It's a tough decision, getting a carbon would mean that i could ride it now (i have only one ss bike atm). It's a long wait for alu one.

Can you help me decide? Carbon vs aluminium
Bikes with exactly the same components, similar weight, different frame.

if you can afford the carbon one - buy it

It will work out cheaper for you to buy a racing license first and then use that racing license to get 15% off the frame price of a Canyon. Email them and ask if this will carry over to full-builds (it used to).

http://www.canyon.com/_en/service/sponsoring.html

^good point

It will work out cheaper for you to buy a racing license first and then use that racing license to get 15% off the frame price of a Canyon. Email them and ask if this will carry over to full-builds (it used to).

http://www.canyon.com/_en/service/sponsoring.html

just called them, they offer it only on frames:(

get the carbon then

you didn't say why i should choose carbon

The ride quality of a carbon bike now is infinitely better than not riding an alloy bike for the next six months.

The ride quality of a carbon bike now is infinitely better than not riding an alloy bike for the next six months.

:)

I'd guess the carbon will be slightly more forgiving, when ridden over long distances. Its not a difference you'd expect to imediatly feel with a quality alu frame, up against a stiff carbon one though. Plus it'll be lighter. Get the carbon.

If the situation regarding availibility was reversed. I'd be pretty happy with the alu. I cant imagine there's much in it.

Get the carbon, it will be loads better

:)
Plus it'll be lighter.

7.35kg for alu and 7.2kg carbon, not much difference really

If the situation regarding availibility was reversed. I'd be pretty happy with the alu. I cant imagine there's much in it.

exactly, but don't wanna make a wrong decision just because i couldn't wait few months

i'm just really afraid of damaging carbon, never had carbon bike before and maybe that's why i'm stressing myself