I never believed or experienced that seat rails make much if any difference. Length, diameter and thickness of the seatpost are far more significant I reckon.

Seat rails? Seat posts? I generally find that to really feel the “compliance” of a given frame you need to be doing the sort of riding that would generally mean getting your arse out of the saddle – fast twisty stuff where you are throwing the bike around.

Like I said in an earlier post, my experiences of swapping every component from a quality aluminium to a quality steel frame makes me believe that different materials do have different feels if everything else is equal.

I’ll second IvanDobski here. I swapped everything from an ally Cannondale frame to a steel Cove frame, then did exactly the same seventeen mile Marlborough ride that I did just before the swap, and the difference was startling. The ‘dale left me absolutely punished, whereas the Cove left me feeling like I could do the ride all over again. The only variable was the frame. Now, I’ll be the first to admit that a quality ally frame can exhibit the same lively qualities that steel and Ti do. However, there is a good reason that springs are not made of aluminium. Ally has a fatigue life, and if I was buying a frame that I was only keeping for a while then passing it on then I’d go ally. If, however, I wanted a frame as a keeper, then steel is the only option. For one reason no-one here has mentioned: repairability. A quality steel frame can have a damaged tube replaced by a framebuilder, and a frame like a Curtis can be easily returned to the guy who actually built it. What are the chances of getting an expensive ally frame repaired easily? Or Ti, for that matter. How about getting a frame customized, with pannier mounts, different disc mounts, modified hose guides? All these can be done with steel, but where do you find a framebuilder in the UK who works in ally or Ti? Steel has at least one magic quality, and I’ve just described it. I’ve had a Ti frame, a Hummer, and I replaced it with a Steel On-One that cost me £250, and frankly I much prefer the steel, if only because I can use huge tyres and stupidly long travel forks, but also because if I drop it hard and ding it I’m just going to shrug it off. I also have an 853 frame, which I wouldn’t swap for anything, not least because it only cost me £250. Get the Curtis. You’ll have the satisfaction of owning something made by a craftsman, and that’s worth more than just the materials.

Ivandobski said, “Like I said in an earlier post, my experiences of swapping every component from a quality aluminium to a quality steel frame makes me believe that different materials do have different feels if everything else is equal.”

Yep, but likewise different frames made from the same material (or similiar) can also feel very different. Ride a Stiffee or a Chameleon back to back with a Scandal and you’ll notice a difference, I’m sure. Ride my brother’s early-90s Rufftrak (massive steel tubes) and my Soul and I absolutely guarantee you will, the Rufftrak is as stiff as a brick wall.

Obviously a stiffee will feel different to a scandal, the question is would an 853 scandal feel different to the aluminium one? And would a pig-iron scandal feel different again?

The shop round the corner from me has several 953 frames in stock in both road and mtb flavours.

Swapping all components from my Pace rc303 to a 456, I found if anything the Pace was very marginally less harsh but the it did have a very long section of seatpost sticking out.

The posts above comparing other swaps only show that different frames ride differently. You can’t say that all (or even most) steel frames are less harsh than alu ones without considering respective designs.

Ti stays, steel main tubes?
Or..
853 front triangle, ti rear?

Depends on the design and what type of bike you’re designing…

[Complete novice sticking his nose in with a question]Ti seat, top tube and seat stays. steel everything else (inc chain stays). Makes the BB area stiffer for power transfer but still makes the frame ‘lighter’? [/Complete novice sticking his nose in with a question]

Ti stays, steel main tubes?
Or..
853 front triangle, ti rear?

I’m lost. How do you join them, sticky tape

If you want stiffness round the bottom bracket use larger diameter tubes, whatever the material

Ah,the weld itself doesnt hold the different tubes together (thats abit niave?)

Correct (for once) Hora – You can’t weld entirely dissimilar materials (at least not when we’re talking about bike frames). For a mixed Ti/Steel frame you’d have to either bolt it together (Gary Fisher CR7 – steel, alu) or stick it together, probably using lugs.

If you want stiffness round the bottom bracket use larger diameter tubes, whatever the material

essentially this is spot on – relative ‘large’ diameter will be different for different materials depending on their Young’s Mod (Stiffness).

Aluminium is less stiff than steel so for the same stiffness you’d need a larger diameter but then you typically also go for even larger diameter still (to reduce flex) to try and prevent it fatiguing prematurely.

Ah, understand. Too much give’ means earlier fatigue/failure. Makes sense/common sense I guess.

Have a read of this if you’re really interested:

http://tinyurl.com/yrlmdr (wiki link)

One of the key things to read about is ‘fatigue limit’ – something that steel and Ti have but aluminium doesn’t – in a nutshell, it means that if you load/unload something made of alu enough times, it will always eventually fatigue whereas if you keep the stress on something made of Ti or steel below the fatigue limit, it will never fail due to fatigue.

if you keep the stress on something made of Ti or steel below the fatigue limit, it will never fail due to fatigue.

Though it has to be said that steel and ti bike frames are stressed FAR beyond the fatigue limit strength. It would be possible to make one that wasn’t, but it would be quite heavy 😉

Yeah, fair point and I did mean to point out that if you design it right, even over the fatigue limit, the number of cycles can be so high that you’re very unlikley to ever reach it (hence the steel lasts forever idea though strictly not true)

Looking for a graph of fatigue life, I found this page which is actually quite good at explaining fatigue in real life

http://www.epi-eng.com/mechanical_engineering_basics/fatigue_in_metals.htm

Whats the new CERN regs added to a typical frame in terms of extra weight?

437.46g per frame.

Cheeky 😉

I generally find that to really feel the “compliance” of a given frame you need to be doing the sort of riding that would generally mean getting your arse out of the saddle – fast twisty stuff where you are throwing the bike around.

And you’d feel that compliance through your feet?

And you’d feel that compliance through your feet?

I was thinking that the other day. And wondering how much more compliant ti pedal axles are than steel ones 😉

Compliance through your feet?

Yes

Well sort of

Imagine this. You are lining up for a left hander. You drop the bike over to the left and force you weight down through your right pedal. On my old steel Kona the flex was huge as the bottom bracket deflects.

Try holding a static bike in front of you. Stand on the pedal nearest and watch the frame flex.

Whether you like this flex is another matter

Whether you can feel this flex in a straight line I’m less sure of…

For any force to be transmitted to a frame, it first has to pass through the tyres. A 2.35 section tyre will absorb a lot more than a 1.9.

But Brant is best qualified to comment on this.

How much vertical compliance can there be in a hardtail frame -1/4″, 1/2″?

How much vertical compliance can there be in a hardtail frame -1/4″, 1/2″?

No numbers to back it up but I’d be surprised if ‘normal’ riding deflected the frame vertically by 1/4″. The seatpost, tyres, saddle hull/padding on the other hand…

That said, I think there’s more to it than just deflection – I think that there’s some sort of damping going on too since despite being sceptical I have found that road bikes with carbon stays feel noticeably smoother over bumps than full aluminium frames. Of course, it could just be coincidence but it’s been common on every carbon-stayed road bike I’d ridden.

“”I never believed or experienced that seat rails make much if any difference. Length, diameter and thickness of the seatpost are far more significant I reckon. “”

I don’t think this is really the case as i’ve had quite a few steel (853 – 725 and columbus) and Ti and they all had 27.2 seat posts – the exception was the external diameter of the ti bikes seat tube (it was a bit bigger) However they all road quite differently. I had a cove hanjob, one of the first ones, and it was really flexy, and for want of a better work zingy. I had a marin too, that was a harsher ride than my kona which has the ride i liked the most, not to flexy feeling, not as harsh as the marin. I think a lot to do with it is the shape and angles of the rear end, snake stays seem a lot flexier, the steepness of the angle of them affects the ride too – the steeper the less verticle complience – stands to reason don’t it.

On the other hand, I reckon that all the wavy bends on the stays do very little in reality though they do look cool 🙂

On the other hand, I reckon that all the wavy bends on the stays do very little in reality though they do look cool

applause from Walsden… 🙂

oh, stop it, brant 😳

rear triangles in low compliance shocker… )

compliance vertically, well there’s not much of it. what a lot of people feel and call ‘magic’ or ‘zingy’ is side to side spring in the frame. frames flex a lot laterally but comparatively little vertically, almost the oposite of what you think would work but when a bike’s laid over in a corner, lateral flex almost beomes an ability to flex vertically (in relation to the bike’s position) so it feels lively and flows over the rough a bit more – or flexes i should say. flex is only a bad thing if there’s too much of it, and one man’s too much flex is another’s ‘magic ride quality’.

hora good idea

and i will let you in on a secret a wee while ago there were several of these mixed material bikes floating about in the composites shop without a nut or bolt or lug in sight to do this unfortunately they do work out to be very expnsive and the way to do it and get the bike to actually have a warranty will remain in the realms of its possible but why

there comes a point where its possible to build anything and actually make it but when you weigh up the pros and cons of making money ,if you were building bikes would you rather sell 100 frames at 250 quid or cater for the 5 people who want that strangely unique thing made of X Y AND Z and will pay 1000 quid for a frame that does pretty much the same

I reckon that you could call carbon joints of ti and steel tubes lugs (assuming of course that’s what you did) even if they weren’t applied as lugs.

im not a fan of lugs …but as usual it was a supposedly readily producable thing which once the company who did the prototype work figured out they could make a quick buck sadly put the cost up

OK, well I’m not sure if that’s a confirmation of what I suggested but that you don’t want to call them lugs (because technically they’re not) or you saying that I’m completely wrong 🙂

I’m envisaging something along the lines of the bamboo bikes shown in the ST mag a few ishs ago.

compositepro true plus the choice of finishing kit would be crucial and an expensive trial and error to get ‘right’ to match the frames characteristics? Plus you need to be able to understand subtle differences in each material/frame…minute differences that only a sensitive soul can feel.

jim

And you’d feel that compliance through your feet?

Yeah I suppose…. rather the change in position of my feet relative to my hands. Or to put it another way I believe I can feel the frame flex around the BB and the steerer. TBH I’m not sure, I believe I can feel it but I’ve given little thought to what I’m actually feeling or how I feel it.

Apologies but can I ever so slightly hijack?

Posted up a thread earlier about opinions on the Genesis Altitude 30, no response yet. Have any of you guys ridden one, or know anyone that has?

Am quite tempted with another steel hardtail (had Rock Lobster before) so am looking for frame only but with a longer toptube. Anything else to recommend?

Thank you so much!

“Posted up a thread earlier about opinions on the Genesis Altitude 30, no response yet. Have any of you guys ridden one, or know anyone that has? “

i have, but i’m biased as i work for them.. a few on here ride the altitude 853. any direct q’s post em through to the genesis site as i pick them up easier than on here.