Custom Steel vs carbon?

Discuss light weight issues concerning road bikes & parts.
2lo8
Posts: 539
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

n1ey wrote:
Wed Nov 21, 2018 10:54 pm
The biggest thing to aero is having a small cross section.
No, that’s not true at all. That comes from people misinterpreting CdA or drag area as reference area because of the word area. CdA is the product of Cd and A, which are drag coefficient and reference area. CdA gives you the overall aerodynamic performance or at least an approximation. A sail or a parachute has a very small cross section but both awful Cd and huge A. Lacking proper reference materials at the moment, the difference in Cd between a cylinder and an airfoil is probably somewhere about 10 times worse. Steel tubes are only going to be in the range of 1/2 to 2/3 the frontal area of a carbon airfoil, not nearly enough to negate the poor Cd of round cross sections.

I asked Variwall to consider making a tunnel tested kammfoil steel down tube for builders who wanted to keep up with modern trends, but they seem to be uninterested in seriously expanding their range. They still have not made proper S3 replacements.
[6.6kg of no carbon fiber]
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by Weenie


n1ey
Posts: 8
Joined: Mon Jul 30, 2012 11:53 am

by n1ey

Interesting thoughts. I posted to see what people have in mind. Right now, I think that reducing the front section and wheel would produce the largest reduction in drag for me.

Testing on my old Roubaix has cda of .45.

I will take a reduction of any sort in the new bike. I also wonder if I should go disc brake and modern steel. I haven't found anyone with the through axles and discs, yet.

bill

ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

If you are a dedicated racer, carbon might be worth it, but...

I have had 5 custom steel bikes built, and wouldn't go for carbon. All by Spino, from Porto Alegre - Brazil (I live close).

I like steeper seat tubes and short head tubes, so unless I ride some flexy TT frame, steel is what I want.

My road bike is 6.85kg with Alpha 340 wheels and light tires. Goes up to some 7.5kg with aero wheels and gp4000 tires. Tubes are Columbus Spirit. Love it. Comfortable and stiff rear when sprinting. Fork is Columbus Futura SL. Frame is 1474g, and could be lighter but I chose some fancy modular hangers and used the propper headtube rings from columbus, which you can avoid with another tube width (done this on my fixie frame). I'm still to upload pics to a gallery on this forum, soon.

The others: my first single speed from them had slacker (normal) seat tube so I sold the frame when I reached the conclusion I wanted it steeper. Second fixie Columbus Life (same stuff as spirit but thicker tube walls). I crashed the rear triangle and still didn't fix it because I had to order new tubes, it was faster to get another fixie built. So this third one is common carbon steel, non-butted, but got some curvy s-bend seatstays that I suppose makes it more comfy. Then I got a 29r gravel, also common steel, for training and touring. The frame has bosses for 5 bottle cages and also for salsa everything cage if I wish, eyelets for rack, fits 60mm tires with room. Love it. I ended up using the fixie only on rainy days..

And last was this road bike, rides like an space ship.

Go for steel, and check Spino, it may be cheaper even with international shipping... They speak fluent english and the framebuilder studied at the Bycicle Academy in USA.

At your weight its probably wise not to go for the thinnest Spirit tubing, but the builder will tell you that.

ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

Oh, unless you really want those grams, it's ok to get the same bike built with cheaper Columbus steel, or Nova tubes. The disc or not to disc question.. well, on a custom bike you can have both: disc fork and some cable-disc caliper, and rim brake on the rear. It's the front wheel that needs power anyway, all you get with a disc rear is it's easier to skid.

My gravel bike has some "Nutt/Absolute" cable actuated calipers with hydraulic double piston action, using old 6600 sti, and works really good. These brakes are dirty cheap. TRP Spyre, Avid bb7, Shimano and Sram got cable options too, so no need for more expensive hydraulic shifters, and you can have lighter frame/rear brake this way. Usually front rim wears faster anyway so the rear rim will be fine.

Still I wouldn't have discs, unless you want a bike with clearance for big tires to allow you to swap wheels and go gravel too, without needing a second bike (why not?).

2lo8
Posts: 539
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

n1ey wrote:
Thu Nov 22, 2018 2:46 pm
Interesting thoughts. I posted to see what people have in mind. Right now, I think that reducing the front section and wheel would produce the largest reduction in drag for me.

Testing on my old Roubaix has cda of .45.

I will take a reduction of any sort in the new bike. I also wonder if I should go disc brake and modern steel. I haven't found anyone with the through axles and discs, yet.

bill
Frontal area is for bike fitters, not for bike design. It just so happens when you get down lower, your torso has both lower frontal area and it increases the length of the cross section, both of which are good for aerodynamics. In bike fitting, you basically never compare frontal area vs cross section. There's not much you can do in bike fits to alter one but not the other.

I don't know if you wanted a steel fork or just wanted a "steel" bike with carbon everything else, but steel disc forks are heavy and harsh riding. If they're not overbuilt, the brakes can bend the fork legs.
[6.6kg of no carbon fiber]
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Your one-stop source for information and reviews on cheap eBay bike junk.

ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

Check this out:
https://ciclicorsa.com/shop/cinelli-vig ... -frameset/
€700 for this frameset including a carbon fork that usually costs some $250+ on its own. The geometry on XS is quite close to my own road bike, but mine has 77 deg ST and HT is a tiny bit shorter.
The Nemo model is €1700 (Spirit tubes), same fork, but slacker geometry. So quite a lot more for the 200-300g of weight savings... Thats $1940. Unless you are a dedicated WW, this Vigorelli is a nice deal IMO.

But then for $1940 (Nemo price) you can probably pay for the Spirit tubes, unpainted fork, order from Spino, get a plane ticket in the off-season for $500 and visit Brazil to pick it up! A good deal too.

BTW I bought my unpainted Futura fork from this website. Only got tubes from australia because an uncle was traveling from Sidney and it was cheaper from Hillbrick website.

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kgt
Posts: 7818
Joined: Sun Jun 18, 2006 10:29 am
Location: Athens, Greece

by kgt

The geometry of the Vigorelli is not that great though.

kb1iub
Posts: 8
Joined: Wed Sep 12, 2018 12:50 pm

by kb1iub

Not sold on going to higher frame. So geometry with bb higher does not sound good.

I can't go lower on a bicycle. So comment on frame fitting seems to be on wrong track. Anything to reduce front end drag slightly would probably be worthwhile if it was at no cost. It should be considered. I don't really believe any the claims in the marketplace especially when I noticed very different takes from manufacturers with large r&d.

More interested in durability thoughts and weight. I am 90kg. The 2000g weight for a XL frame seems to push this off when durability could be questioned.

Would true temper or Columbus hold up ?

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ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

Liking that geometry depends on your flexibility. I ride something even steeper and I like it. I can have flat horizontal back, and I'm ok with it. I also hate the thought of ever hitting pedals on the ground, so I chose higher BB, no regrets. I don't coast at corners. I'm a fixie rider too so that's where it came from. If it works on a fixie, why not having the same geometry on my road bike?

But you can order whatever geometry you want if you contact Cinelli. Or any other framebuilder. That website has other options too.

That Vigorelli ~is~ Columbus. I see no reason why it wouldn't hold 90kg...

But after all, are you racing that bike or is it just for weekend and group rides? Gravel bikes are great. I do most of my riding and training on my gravel since I built it. Just have two wheelsets, tarmac and offroad, thats two bikes in one. You can get the second wheelset later...

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kgt
Posts: 7818
Joined: Sun Jun 18, 2006 10:29 am
Location: Athens, Greece

by kgt

To anyone who is interested in steel frames I would suggest to look for something NOS. You can find (at Ebay or elsewhere) amazing frames with top, lw Columbus or Deda tubesets for 700-800 euros.

Marin
Posts: 3518
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

2lo8 wrote:
Thu Nov 22, 2018 12:10 am
parachute has a very small cross section
no :)

2lo8
Posts: 539
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

Marin wrote:
Sun Nov 25, 2018 1:46 pm
2lo8 wrote:
Thu Nov 22, 2018 12:10 am
parachute has a very small cross section
no :)
The profile cross section.
[6.6kg of no carbon fiber]
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