38
votes
Accepted
Why did curved forks disappear?
The main reason is the materials used.
Basically, on all bikes with bent forks the bent forks are made of steel. Steel has been mostly replaced by carbon and aluminium.
While steel is heavier, it is ...
- 2,370
32
votes
How does brazing and welding not ruin the heat treat on steel tubes?
tl;dr heating chromoly to brass-brazing temperature doesn't really change it, at all; the steel was born hot and heating it back up does nothing to it other than oxidizing the surface if you don't ...
- 3,316
18
votes
Accepted
Is it possible to rebuild a a steel bike frame (to make it lighter) by welding aluminum tubes
I would not. Instead I'd strongly recommend you look at buying the bike you want rather than chopping up a working vintage bike. At best you'll come out with something worse than a replacement ...
- 121k
17
votes
Accepted
Why almost every custom framebuilder builds steel bikes, but not many work with aluminum?
When you consider the overall outcome - the final bike, not just the frame, hand building in aluminum rarely makes sense. Modern aluminum factory frames are hydro formed into all sorts of engineered ...
- 49.1k
17
votes
Why did curved forks disappear?
Frames and forks were made of tubes that are brazed into lugs. Lugs are cast standard parts. Frames are sized by using tubes of the correct length. The respecive production processes makes lugs stiff ...
- 9,610
16
votes
Why did curved forks disappear?
A big part of the change from curved to straight forks is the engineering requirements for disc brakes.
Curved forks provide structural flexibility, in that forces applied to the tire become ...
- 1,531
14
votes
Accepted
How to attach cable mounting points to a bicycle frame?
I'd go with full housing for both brake and gear cables and hold the cables on with cable clamps. There are many kinds of cable clamps to choose from. I prefer the type that have a screw clamp over ...
- 20.7k
13
votes
Accepted
Feasibility of bike frame design by a layperson
Interesting question and way of looking at it.
Here's my take: those in the bike world who would seem most qualified to design scientifically optimal frames, which involves both mastery of all the ...
- 81.9k
11
votes
Is it possible to rebuild a a steel bike frame (to make it lighter) by welding aluminum tubes
There is a lot more to a bike frame than just weight. If there is one thing early aluminum frames taught us is that straight gauge aluminum rides harsh! Modern aluminum frames typically employ ...
- 30.5k
11
votes
Spring frame in place of shocks?
Softride is one of the bigger names in this area. Their main bike design exchanged the top/seat tube and seat stays for a composite materials "beam" that cantilevered back to a saddle in ...
- 121k
10
votes
Accepted
Why are bicycle tubing diameters often metric approximations of imperial measurements?
The decimal sizes such as 25.4 and 28.6mm are not "unusual" sizes. They are actually the standard sizes. You can count on engineers to do the easy and cheap thing, so they use the standard ...
- 3,316
10
votes
Accepted
What are these parts of the frame called?
Those are cantilever or V-brake bosses. In cycling, a boss is a bump or protrusion. They are usually mounting points, and in this case the brake boss holds the post that your brake caliper is bolted ...
- 29.7k
10
votes
Why did curved forks disappear?
In addition to what was discussed in other answers, there is one significant detail: flat mount disc brakes. The flat mount brakes that are almost universal on road bikes require a flat mounting point ...
- 21.8k
10
votes
Accepted
Is there a reason why it was said that the distance between the seat tube and the rear wheel should be as small as possible on a road bike?
The distance will depend on the tyre width you choose for the stage on that day. Today's road bikes allow a wider range of tyre widths partially thanks to the adaption of disc brakes. For time trial ...
- 16.1k
10
votes
Is there a reason why it was said that the distance between the seat tube and the rear wheel should be as small as possible on a road bike?
This hasn't necessarily always been about aerodynamics, although it can be. There have been bikes with super-short chainstays for a long time; the most extreme example is the Rigi Bici Corta, which ...
- 29.2k
7
votes
3D printing frames?
Five years later, it turns out it was just a matter of time until 3D-printed (additive printing) titanium frames showed up:
https://www.pinkbike.com/news/the-3d-printed-moorhuhn-is-now-available-in-...
- 3,534
7
votes
Spring frame in place of shocks?
The reason why flexible forks and stays are not used for suspension is geometry. With flexible forks blades or stays there is nothing that makes the left and right side of the fork flex together. ...
- 21.8k
7
votes
Accepted
What is the advantage on road bikes where the seat stay merges into the upper part of the seat tube, but well below the top tube
It offers both improved comfort (less resistance to vertical forces) and improved aerodynamics.
Road.cc have a large article discussing this subject: https://road.cc/content/feature/what-are-dropped-...
- 18.3k
6
votes
Feasibility of bike frame design by a layperson
I remember seeing courses about how to make a bike frame, but they were not about new designs, they used standard designs and the courses were about selection of tube, welding/brazing, finishing, etc.
...
- 121k
6
votes
Spring frame in place of shocks?
Too much "spring" is not always a good thing, especially when it allows the frame to flex in directions it is not supposed to.
There is a video by Colin Furze where he makes several attempts ...
- 14.4k
6
votes
Accepted
Are worse QC'ed carbon frames chosen for pairing with lower tier components? Does it matter?
Short answer: No.
Bike manufacturers are certainly aware of the QC issues inherent in the carbon fiber manufacturing process and ways to both test for and mitigate them, and it is also true that for ...
- 925
6
votes
Accepted
How do vintage steel frames compare to modern ones?
The ad copy is saying that the frame has some of Tange's 531-esque product of the time, i.e. a steel with manganese and molybdenum alloying elements. It's either all Tange, or some Tange and some 1024/...
- 81.9k
6
votes
Accepted
Aluminium frame alterations
First up - figure out your budget. Frame repairs are not cheap and skill costs money. It is conceivable that this repair costs more than a replacement frame that does suit you.
It may be that ...
- 121k
5
votes
Why almost every custom framebuilder builds steel bikes, but not many work with aluminum?
Mattnz's answer is canonical and addresses aluminum, steel, and titanium frames. Until we can easily 3d print metal frames, custom frames are going to be tube based. Hydroforming metal for one-off ...
- 29.1k
5
votes
Can I fit a modern internally geared hub on an old bike ?
While you probably could cold set it, the Sturmey-Archer XRF-8 is available in a version with 120mm OLN dimension.
(And you almost certainly can fit a modern bottom bracket. Worst case, have the ...
- 2,536
5
votes
Dent on aluminium frame?
This is only engineering judgement, not technical analysis: the damage does not appear particularly serious or significant at that location. As Daniel advises above, keep an eye on it for cracks ...
- 258
5
votes
What are these parts of the frame called?
Weiwen's answer is correct - this is a V brake mount, and the three spring holes are part of that.
But the more-general phrase for something like this is a "braze-on" because in the days of ...
- 121k
5
votes
Accepted
Any good / free software to design lugs?
All you need here is any of the pieces of software that framebuilders use to print stickers for hand-mitering tubes. You input an angle, the diameters, and which tube will be the "parent," ...
- 81.9k
5
votes
How thick is a traditional steel road bike lug?
I have handled quite a few lugs of different types. Some are cast and some are made out of pressed sheet steel then curved and jointed shut to make the 3D shape. Other people create a fillet joint in ...
- 13.7k
4
votes
Accepted
Lugged carbon frame repair
It should be possible to repair the frame, the big question is whether you'll be able to find a replacement tube or will you have to make it yourself. Making the tube isn't hard, it's just messy.
The ...
- 23.3k
Only top scored, non community-wiki answers of a minimum length are eligible