Steel or aluminium frame?

[Druid]

Funny you mention that. The two bikes I spoke of above, a Reynolds 753 and a Giant 6061T are both on Mavic SUPS but the steel bike's wheels are cross spoked and the alloy is radial. I've never tried swapping the front wheels to see if there is a difference in the buzz I get though the front. However you can literally see the steel fork flex with the bad road surface while you can see the wheel bounce under the unflinching alloy fork. The wheel is not to blame for the difference in feel here.

 

[sletti]

In reality wheel are so stiff that they do not deform radially by any detetable ammount when riding.

I wonder of spoke count makes much of a difference then, and my 3x has twice the spokes in it.

Obviously a single spoked wheel would radially deform rather catastrophically, with two to five spoke wheels offering little to nothing else (this is assuming spoke under tension, rather than a carbon monocoque spoke configuration, i.e. Spinergy, etc). I guess six spokes is probably the minimum number of spokes that could hold a hub in the centre of a rim, but I suppose you would have to make the rim so stiff to survive it's lack of support that it would have an adverse effect on ride quality.

So my logic suggests that if you increase the spoke count you could make the rim less stiff, and maybe this could have an effect on radial compliance.

Keep adding spokes and I guess you would end up with a disk wheel (A heavy one that was not very smooth but would sound great in a skiffle band).

Don t know if it makes a difference; I'm just riffing on the notion...

 

[markyp]

Same for me. Two 531c frames and they ride so differently. However, the 753 peugeot is joy to ride.

Riders weight must really be taken into consideration.....also when considering road buzz......

I've got an 87' 531c which is dull to ride and a 77' 531 (standard) which is an absolute pleasure, although my joy is my 95 Columbus Max. The 531's are very much like for like spec wise but a world of difference apart in ride quality.

 

[bm0p700f]

Again theortially and experimentaly spoke count make little difference to vertical (radial wheel flex). Most wheels have a radial stiffness in the order of 3000-4000N/mm That is 4000N (or 400kg equivelent) of load for 1mm of vertial defletion.

Lateral stiffness is dependent in part on the number of spokes and there gauge as well as the rim.

Radial wheel stiffness = rim stiffness/(1+(rim stiffness/spoke stiffness))

So as steel spokes are about 10 as stiff as the rim (steel vs alu alloy) then the forumula reduces to Radial wheel stiffness = rim stiffness/1.1

In other words radial wheel stiffness ~ rim stiffness.

So rim stiffness determines radial wheel stiffness not the number spokes, lacing pattern or guage. Thicker/more spokes gauge spokes will just make the bottom term (~1.1) even closer to 1 thus raising stiffness slightly very slightly but not by any noticeable ammount.

I worked out that the vertical acceleration on the front wheel caused by a load big enough to produce a 1mm deformation in the rim vertially would result in a instaneous vertical acceleration of about 8g.

Imagine the the rim + spoke as a piar of springs. One spring is of very high stiffness and the other is of low stiffness. Both are linked together and a weight is hung of them. The very stiff sping will not extend much but the soft spring will. So extension in this case is determined by the extension of the soft spring. The same applies to a wheel with a radial load.

On sheldon's brown's site there is a wheel stiffness page and lateral stiffness was tested. 2.0/1.8/2.0mm spokes and 2.0mm spokes on the same hub and rim were compared and the thicker spokes resulted in about 10% greater lateral wheel stiffness.

Of course 3x wheels have longer spokes so from a lateral stiffnes point of view are less stiff than a radially spoked wheel. In order of inrceasing lateral stiffness 4x, 3x, 2x, 1x, radial

 

[Lazarus]

What a good original topic " Alu frames / Steel Frames". Lots of interesting stuff re: spokes/radial/2cross/3cross, rim type, flex, parts etc etc, but the main topic (and confessions of steel guys now liking alu) makes me smile because, "I'm not alone ".

I listed an alu framed rebuild on here about 4-6 weeks ago for £200 to the door. I got the Zeus badged alu frame as part of an ebay buy. The frame was adorned with Campagnolo Chorus 9speed kit (STI's type), basically top end Campagnolo. I was going to let the frame become a rough run around for someone until I took it on it's customary post build Parbold Hill test ride (17miles of varying terrain from long climbs to short sharp very steep).

Up until 3 years ago I had ridden my 60cm Faggin Columbus SL, built by the Von Hacht brothers of Hamburg in 1984 and nothing else. It was custom built for me by them after very extensive measuring. It became me on the 1st ride, my 3rd leg, my 4th arm, it quite simply attached itself to me like it was a genuine part of me. I rode 180km the very next day with the 2 brothers & a gang. It was a 100% perfect ride. Fast when it needed to be, comfortable, you get the picture. My Faggin is me. In 1998 Keith Coppells of Maghull Liverpool rebuilt the bike for me with a complete 1st edition Chorus groupset, the only exception was the SR hubs laced to MA40 wheels.

In 2009 I then bought a 54cm Paganini Sioux, Columbus SL. When I rode it the difference in ride was north from south to my Faggin. The Paganini is a complete Athena 1st edition groupset (almost identical to the same aged Chorus). SR hubs on shallow v Alesa rims (beautiful wheels). The Paganini made me aggressive in the saddle, it always made me keep going, like it dragged me into its smaller tighter geometry. A very unforgiving bike if you're feeling lazy, but repays the rider 10 fold if you keep cadence.

Now, after riding " Geoffrey Butler 753r (amazing ride for effortless speed ), Bonavia 531 (super smooth comfort), Raleigh Gran Luxe 531c (super smooth but almost like 753), Faggin & Paganini Columbus SL (like a second skin on my body type of ride), Turbo Mecacycle Vitus tubed (very wierd in a nice way ride), lugged, fillet brased, I ride with both shame & pride the bike I almost threw away because of unfounded prejudices " An aluminium Zeus with alu forks ".

"The ride quality is so smooth and effortless. It eats hills like they are speed bumps. It is quick out the trap (traffic lights). Feels heavy & bulky underneath, but is actually light & responsive. A strong easy going ride, I last used it on a this 58mile ride (link here http://connect.garmin.com/activity/185706002). I go fast that feels slower. Nowhere near as fast as my others at top whack, but it pays back energy on long haul. I'm totally smitten with its pure qualities that because of its frame type are hidden by prejudice. I suspect this is because some of the earlier alu frames where crap and the word got out that they where so. Truth is "its the best frame I've got as an all rounder ". So glad I never sold it Gotta go ... TBC Later everyone Laz.

 

[onegaishimasu]

Lazarus, interesting comments and an interesting bike history! Actually, I'm struck by the fact that not many people here have ridden carbon frames. Yes, I know it's the retrobike forum and all, but retro and new can cohabit the garage quite happily! I mention this because a good carbon frame combines the best properties of steel (vibration dampning) and alu (stiffness/zip) - a good carbon frame simply is a delight to ride, and the compromises can be dialled right in. I recommend trying them out.

The other point to bear in mind - and this hasn't been mentioned - is the impact of size, weight, riding style on perceptions of the frame. Smaller frames are stiffer than large frames (unless the manufacturer has taken very good care in their design, which does happen with better frames, or indeed custom frames where the tubing has been well selected). Thus, a small light rider may feel totally beat up on a frame that a strong tall rider thinks is a noodle - a frame needs appropriate ride characteristics for the rider. Thinking partly about the 60cm Zeus - I ride big frames too, and my issue is generally not enough frame stiffness rather than not enough ride comfort. This is inverted with my partner (who rides 49cm frames), who is extremely happy on a compliant steel frame.

 

[markyp]

My Giant TCR (small size, full carbon) is not as "comfortable" as my 753 frame, but both are more comfortable than my aluminium Giant.
There! a full scientific analysis of steel v carbon v aluminium.

Mark

 

[Lazarus]

Hi again I haven't tried carbon yet except for a quick go on my nephews and it was a beautiful ride, BUT (sorry its a big but), he's paid around the 2K (£2000) mark with all the bells and whistles attached. I simply don't have that sort of pocket money, and even if I did I'm afraid there are too many bikes I could buy for that amount of money, that will live longer, age better, and be worth more when I'm gone.

I have seen some absolutely mind bendingly beautiful bikes in my time, nearly all steel. For sheer beauty the Italian SL-SLX-Brain Columbus types with their chrome, British, French, Spanish .... "there are soooo many ". I'm not against carbon in any way, but If I had £2000 it would be a Colnago Bi-titan kitted in 1st edition C-Record/Delta (but not the brakes ... don't like them). This is the thing about bikes from the 70's to the 90's (not excluding everything else but this is my era). To others I suspect a genuine Ti Raleigh 753 full Campag SR.

As for ride quality I guess what I was saying is " Custom built for me & me only is the best option, but in reality you can't own and ride many many bikes because it spoils the relationship between you and your first machine. It's like cheating on the wife after being straight & honest for many many years, the thrill of something different is there, but it fades fast, (unless of course your 1st was a mistake). Riding all the bikes I have these last 3 years has spoilt how I feel about my Faggin, a machine that has never failed me on any level. I'm glad I've lived long enough to have used this Zeus Aluminium because my predjudices were unfounded, they can be beautiful too

I'm going home to the missus soon, real soon, after all my flings & affairs & flirting with all the other beauties in this world, simply because I love her to bits because she's as good to look at today as she ever was when they built her. I don't want to fall out of love with my first I have the experience now of having had a few good flings, some very memorable, but good old faithful calls ... and it'll be nice to get back in her saddle ... and stay there The Zeus will remain as the "housemaid" to do all the dirty work. I can say all of this because "I'm never going to win the TdF (haven't got the heart to shame all those pro's LOL) so ultimate speed can be traded for comfort.

Still a great post because it is finally opening the door on the "prejudices Alu suffers needlessly". Alu frames are like ANY frame ... "A frame built by pro's who know their stuff, from superior materials that work, any frame is a good frame". This is my thoughts re: the Zeus an alu frame that even I am guilty of treating as second class, but in reality it was built from high quality tubes by someone who knew their aluminiums from their carbons from their steels. I just wish I knew who built it because Zeus absolutely did not make this frame, not according to their catalogues, but someone did, and boy did they get it right in every department, even the geometries are tight, very tight. Later everyone, Laz.

 

[sletti]

Lazarus, dear boy, you absolutely get it in spades. Or rather, your world view is in utter harmony with my own.

 

[onegaishimasu]

"A frame built by pro's who know their stuff, from superior materials that work, any frame is a good frame"

Yeah, this is the bottom line, well said!

However, carbon doesn't have to be expensive... very decent secondhand frames (from a loving home) can be had for not much more than a vintage steel frame. E.g. I paid a touch over £300 for the frame and forks of my current number 1 ride, which was a pro-level frame and one that was extremely common in the peloton up to about 5/6 years ago.