Sick of lack of geometry information! (**rant alert**)

neeb

Am I the only person who is continually pissed off with this? Increasingly manufacturers do not provide full geometry information for their framesets, and do not respond to email queries about it. I would do a "name and shame", except it is the majority of manufacturers who now do this...

The most commonly missing information is fork rake (offset), which is essential to calculate trail along with head tube angle. Some manufacturers (e.g. Colnago) won't even tell you the head tube angle! Despite several emails to Bianchi, they are still apparently ignorant of the fork rake on their own frames. Part of the reason for this secrecy is that many or most manufacturers save money by specifying exactly the same fork on all of their frames, usually with around 43mm of offset. This works fine with a 73 degree head tube, but produces massive amounts of trail and sluggish steering with a 71.5 degree head tube. Manufacturers should be specifying forks with more offset on smaller frame sizes with slacker headtubes, but they don't, because this would cost more, and they hide the fact by refusing to tell you the full geometry information. Why do we put up with this??

The other thing that has been driving me mad recently is the lack of setback information for integrated and/or dedicated seatposts. Many top end frames these days come supplied with their own seatposts or seatmasts and can't take 3rd party replacements, and yet the setback information is almost invariably lacking from the geometry charts. This information is essential to be able to know if you will be able to setup your saddle position without having the saddle at one or either extreme end of the rails, or even not be able to set it up at all. In my case I have a relatively small saddle/BB setback, which in fact can't be replicated at all on a medium frame with a 73.5 seat tube angle and a dedicated seatmast with 25mm of setback (so I can't ever ride a Bianchi Oltre for example). Yet trying to get this information from the manufacturers, or trying to find out if there are alternative seatmast/seatpost options available with different setbacks, is like trying to get blood from a stone... Usually emails are unanswered, and if they are answered you are more often than not fobbed off with an excuse for not providing the information. Sorry, but if I am contemplating spending several grand on a high-end frameset I expect to be able to find out if it will fit me or not, and this is simply completely unacceptable.

Do most people simply not know or not care about proper fit and don't think about it when considering buying a new frame? I have to say that reviews of new bikes in magazines and on websites such as Bike Radar do nothing to address this problem. Invariably, only a single frame size is tested and if geometry information is provided it is incomplete and only for that one frame size. All of the guff written about how the bike handles (assuming it isn't completely subjective to begin with) is completely specific to the geometry of that frame size. Magazines and reviewers need to take a stand, do their job properly, and insist that manufacturers provide them with full geometry information before they review frames, and discuss in the review how geometry differences across the size range are likely to affect handling characteristics.

Strith

Nice rant. Who are you having problems with? I had some issues looking for my last bike, but cannondale are pretty comprehensive in theire geo specs, chack them out.

neeb

Strith wrote:

Nice rant. Who are you having problems with? I had some issues looking for my last bike, but cannondale are pretty comprehensive in theire geo specs, chack them out.

Yeah, Cannondale are pretty good and because they don't have integrated/dedicated seat posts the setback isn't an issue. They still use the same fork for all frame sizes, but at least they admit it..

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Dess1e

Look's website has pretty comprehensive geometries across it's range/ sizes.

http://www.lookcycle.com/media/catalog/ ... 013_34.pdf

Strith

Actually I know cannondale use two different rake forks depending of frame size, as do specialized. That may not be any use to you but it's good to know. You can buy the different 'dale forks aftermarket too.
I always get the feeling that most of the italian bike companies do less research into their designs than the likes of Bmc, Look, spesh, 'dale etc do.

neeb

Yup, Look are good too. Another good one is Swift, whose Ultravox frame has had some great reviews:

http://www.swiftcarbon.com/bikes/ultravox-ti/

They do actually have two fork rakes too, 50mm for the smaller sizes and 43mm for the larger ones. A pity I'm right between two of their sizes.

It's those companies that do provide full information that stand out though, not the majority that don't...

Pross

neeb wrote:

Some manufacturers (e.g. Colnago) won't even tell you the head tube angle!

Can't it be calculated from the various data on here http://www.colnago.com/c59-italia/ ?
There seems to be sufficient information but my maths must be crap as I got an angle of 70 degrees which doesn't seem right :? .

Grill

neeb wrote:

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Ummm, I was able to find complete geometry on all these. Colnago's lack of head tube angle is easily extrapolated and was just a matter of Googling.

neeb

Grill wrote:

neeb wrote:

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Ummm, I was able to find complete geometry on all these. Colnago's lack of head tube angle is easily extrapolated and was just a matter of Googling.

I'm at a loss to see how you would calculate head tube angle from the link posted above.

And where if anywhere did you find fork offset and seatmast setback for the Bianchi Oltre and/or Wilier Cento Uno SR?

<edit> OK, you can find the Oltre seatmast setback if you google around, but´I haven't found this for the Wilier and I haven't found the fork offsets for either.

migrantwing

That Swift is a beauty.

Pituophis

Ribble seem to give pretty comprehensive data for their frames.

Stedman

For me it is standard 170mm crank length that manufacturers insist that you have fitted on their small frames. Try getting a 165mm crank length retro fitted on a top end bike!

lotus49

Giant seem to provide this sort of information on their web site as well.

neeb

lotus49 wrote:

Giant seem to provide this sort of information on their web site as well.

I couldn't find fork offset or seatmast setback in the geo chart - is it hidden somewhere else on the site?

Grill

neeb wrote:

Grill wrote:

neeb wrote:

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Ummm, I was able to find complete geometry on all these. Colnago's lack of head tube angle is easily extrapolated and was just a matter of Googling.

I'm at a loss to see how you would calculate head tube angle from the link posted above.

And where if anywhere did you find fork offset and seatmast setback for the Bianchi Oltre and/or Wilier Cento Uno SR?

<edit> OK, you can find the Oltre seatmast setback if you google around, but´I haven't found this for the Wilier and I haven't found the fork offsets for either.

http://velobase.com/resource_tools/ForkCalc.aspx

Oltre looks to be 10mm (call Epic and they'll tell you for certain) and the Wilier looks like it's using the 25mm Ritchey topper.

Hoopdriver

You can always go custom...

neeb

Grill wrote:

http://velobase.com/resource_tools/ForkCalc.aspx

Oltre looks to be 10mm (call Epic and they'll tell you for certain) and the Wilier looks like it's using the 25mm Ritchey topper.

That link doesn't help unfortunately- if you only have head tube angle you can't can't calculate trail or fork rake/offset. That's the problem I was talking about, so many manufacturers these days only give head tube angle (Colnago don't even do that), and without rake you can't calculate trail (or visa versa).

The Oltre seatmast setback is 25mm, I found that out elsewhere after a lot of hassle.

Yup, would make sense if the Ritchey was also 25mm, thanks. That's too much for me unfortunately. Seems to be the same with most integrated posts, they all have dedicated masts with large amounts of setback, so you are stuck if you want a relatively small BB/saddle setback. One nice exception is the Scott Foil, which I think has the option of either a zero offset or larger offset seat mast.

neeb

Hoopdriver wrote:

You can always go custom...

Yes, a legend would be tempting...

But it shouldn't be necessary to go custom unless you have extreme measurements - providing you are able to get the full geo for all available frames, and assuming it's possible to swap seatposts to get the right setback if necessary, there should be some that will fit. My current bike is a perfect fit, it has a pretty steep seat tube angle at 74.5, which combined with a small setback post (16mm) works very well. Similarly with a 73 degree seat tube angle I can get a good fit with a zero offset post. It's just if the only available post has 25mm of setback, I'm screwed for any seat tube angle much less than about 75...

Think I'll just stick with my current frame, it's excellent anyway. It's only lust and winter blues that's having me looking at other frames, and if the manufacturers won't cooperate with my practical requirements they can stick it. Marketing fail!

Grill

neeb wrote:

Grill wrote:

http://velobase.com/resource_tools/ForkCalc.aspx

Oltre looks to be 10mm (call Epic and they'll tell you for certain) and the Wilier looks like it's using the 25mm Ritchey topper.

That link doesn't help unfortunately- if you only have head tube angle you can't can't calculate trail or fork rake/offset. That's the problem I was talking about, so many manufacturers these days only give head tube angle (Colnago don't even do that), and without rake you can't calculate trail (or visa versa).

The Oltre seatmast setback is 25mm, I found that out elsewhere after a lot of hassle.

Yup, would make sense if the Ritchey was also 25mm, thanks. That's too much for me unfortunately. Seems to be the same with most integrated posts, they all have dedicated masts with large amounts of setback, so you are stuck if you want a relatively small BB/saddle setback. One nice exception is the Scott Foil, which I think has the option of either a zero offset or larger offset seat mast.

You can order a different topper direct from Ritchey. Unfortunately you can't order the post for the Foil, so you're stuck with inline unless you order 56cm or larger...

neeb

Grill wrote:

You can order a different topper direct from Ritchey.

You reckon it would fit? I was trying to work that out, but I got the impression that the Wilier had a squared-off section seat tube and the standard Ritchey one was for a round tube. Might be wrong on that though.

Grill wrote:

Unfortunately you can't order the post for the Foil, so you're stuck with inline unless you order 56cm or larger...

Which would suit me fine, as I would be a 54 and would need the inline...

Hmm.. Nice bike by all accounts... and the 54 would be a perfect fit...

Grill

You'll probably need to contact Ritchey direct to get hold of one, but they do the seat topper on the Plasma and I know I can order a longer one from them. Best bet is to post here: http://forums.roadbikereview.com/ritchey/ as there's a Ritchey rep who is super helpful.

The Foil is amazing, which is why I have 2 in a 54...

colsoop

I agree some manafacturers are quite poor with the information they supply on their bikes, but the majority of people wouldn't know much about the charts - seat angles setbacks etc.

Although you shouldn't have to you may get a better response if you asked your questions to a dealer who can then get the info from the bike company. Some companies just wont deal with an individual which is disapointing.

Epic cycles are quite good for info if your lusting after an Oltre, im sure they could help.

bikingjohn

I think the geometry spec are for more experienced riders. I'd at least compare the reach and stack of existing bike and new bike to *imagine* how I'd position on the new bike.

neeb

You would think anyone contemplating spending 2 or 3 grand on a high end frame would know about bike geometry and be able to work out whether it would fit them or not... I guess that this is not always the case however!

Grill

neeb wrote:

You would think anyone contemplating spending 2 or 3 grand on a high end frame would know about bike geometry and be able to work out whether it would fit them or not... I guess that this is not always the case however!

How many Ferrari owners actually know what makes it go?

giropaul

By coincidence I've just been re-reading a 1965 book - "Cycle Racing".

At that time UK riders almost always specified the geometry and dimensions of their bike to the frame builder. However, to quote from the book:
"On the Continent, where generally they ride faster, they take a different view. The manufactureres of each of the leading countries, France, Italy and Belgium, have evolved a particular design.......... and very nearly standardised it.. And the riders, realising that it rests with them, not the machine, how good they are, have been content to accept these standards. Abroad one orders a road bicycle or a track bicycle, quotes the frame size, takes delivery and gets on with the job."

Pross

neeb wrote:

Grill wrote:

neeb wrote:

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Ummm, I was able to find complete geometry on all these. Colnago's lack of head tube angle is easily extrapolated and was just a matter of Googling.

I'm at a loss to see how you would calculate head tube angle from the link posted above.

Assuming you mean the Colnago link you have:-

a) The horizontal top tube length and seat cluster offset - take the one from the other to give the horizontal distance from the centre of BB to centre of HT (lets call this dimension x).
b) Using the seat tube length, seat angle and seat cluster offset you can calculate the perpendicular height from the BB to the centre of the top tube (dimension y).
c) The front centre dimension gives the distance from the centre of the BB to the centre of the front dropout (dimension z)

From the above we can produce a triangle formed by the distance from the centre of head tube to centre of front dropout (dimesnion z - dimension x), the perpendicular height from the centre of BB to centre of top tube (dimension y) and the head tube angle which can then be calculated by simple trigonometry. However, I keep coming up with a 70 degree angle which seems too slack and suggests there is either something wrong with the dimensions or, more likely, my methodology!

gloomyandy

Aren't you missing the fork offset/rake out from that calculation?

Pross

gloomyandy wrote:

Aren't you missing the fork offset/rake out from that calculation?

That' what I wasn't sure about but from a quick scientific check (I put a rule on the picture of the bike on the screen)the fork is straight and the centre of the dropout is in line with the centre of the head tube.

EDIT A Google search suggest the fork offset is 43mm across the Colnago range which would make the head tube angle a far more likely 74 degrees.

rich164h

I think you're right that when you're spending this much money having access to simple infomration that could be measured by anyone if they had access to a frame should just be published and easily available. It's not exactly the equivilent of asking some industrial secret is it!

I can also see it from a slightly diffent angle though, that for the seat post setback, I rather think of that as a replaceable part (along with stem, saddle and bars) that I may or may not have to replace almost immediately to get the fit right. The fact that it's not published doesn't therefore really change my decision about whether or not to buy the bike overall. Maybe they also think about things in this way? They can only supply components that fit an "average" person. How many people have exactly "average" dimensions for each and every aspect of their body? Very few I'd guess. I don't know anything about seat masts though and whether these are much harder to find replacement for though, so perhaps if there's only one size and no after market alternatives that fits the frame this is a major issue.

With respect to the fork angle, I'm not sure that having that angle known is that important either, unless it is at an extreme angle. I agree that a change in the angle can have a dramatic affect in handling etc but then so can weight distribution, stem length, bar width, wheel weight, tyre choice etc etc and so you're only really going to understand what the handling is like from riding the bike yourself, or relying on reviews from people that have. I'm not sure I could infer anything about the difference in handling between brand A bike with an angle of X vs brand B with an angle of Y. There are too many variables, unless of course, as I said above, the differences were significant/extreme.

neeb

Pross wrote:

neeb wrote:

Grill wrote:

neeb wrote:

Had problems with Bianchi, Colnago, Wilier amongst others too numerous to mention.

Ummm, I was able to find complete geometry on all these. Colnago's lack of head tube angle is easily extrapolated and was just a matter of Googling.

I'm at a loss to see how you would calculate head tube angle from the link posted above.

Assuming you mean the Colnago link you have:-

a) The horizontal top tube length and seat cluster offset - take the one from the other to give the horizontal distance from the centre of BB to centre of HT (lets call this dimension x).
b) Using the seat tube length, seat angle and seat cluster offset you can calculate the perpendicular height from the BB to the centre of the top tube (dimension y).
c) The front centre dimension gives the distance from the centre of the BB to the centre of the front dropout (dimension z)

From the above we can produce a triangle formed by the distance from the centre of head tube to centre of front dropout (dimesnion z - dimension x), the perpendicular height from the centre of BB to centre of top tube (dimension y) and the head tube angle which can then be calculated by simple trigonometry. However, I keep coming up with a 70 degree angle which seems too slack and suggests there is either something wrong with the dimensions or, more likely, my methodology!

Nice try, but doesn't work I'm afraid, for two different reasons:

1) Although on close inspection A in the diagram is the horizontal front-centre distance from a vertical line through the BB to the centre of the dropout, and so you can indeed subtract dimension x from dimension z to get the horizontal distance from the centre of the head tube to a vertical line running through the centre of the front drop out, unfortunately dimension y isn't the vertical distance from this line to the centre of the top tube - you would need to subtract bottom bracket drop to get this line of your triangle, and BB drop is another bit of missing data from our friends at Colnago...

2) If you could subtract BB drop from dimension y to get the second side of your triangle, you could indeed calculate an angle, but it wouldn't quite be the angle of the headtube, but rather an angle representing the angle of the headtube modified by the fork offset. There would be no way to separate this into its two components, i.e. the head tube angle and the fork offset...

That' what I wasn't sure about but from a quick scientific check (I put a rule on the picture of the bike on the screen)the fork is straight and the centre of the dropout is in line with the centre of the head tube.

The fork is only straight from the bottom of the headtube to the drop outs, it will diverge at an angle from the crown - this is what produces the fork rake or offset (it doesn't matter whether the offset is produced by the fork curving or by a straight fork going off at an angle, but the fork will always have an offset...