from Rookie’s keyboard,
Hello, friends!
I am trying to keep up with my schedule, but sometimes I fell behind.
No more excuses.
Today, I have prepared a post on a somewhat obscure topic – wishbone seat stays. I actually have them on my retro road bike, and can therefore talk from 1st hand experience/observation.
Let’s start with the basic theory!
The seat stays are the tubing going from the seat tube to the rear dropouts.
Standard seat stays consist of two distinct tubes welded or brazed to the seat tube.
Wishbone seat stays, however, are attached to a monotube going to the seat tube.
The shape of mono seat stays is close to that of a bird’s wishbone.
A curious fact: Some people believe that wishbones bring good luck. There’s a ritual/tradition during which two individuals hold a wishbone and think of a wish.
Then they break the wishbone. The wish of the person left with the larger piece is expected to come true. (Hence the name – “wishbone”.)
The Pros
- A Stiffer Rear Triangle
Wishbones seat stays do not flex as much as the regular ones. The result is a stiffer rear triangle (at least in theory).
Hence wishbone frames are considered better for cantilever brakes – a brake model that creates lots of stress in the area.
- Faster Production Process
Wishbone seat stays a.k.a. mono stays are sometimes chosen as a way to speed up mass frame production.
The wishbone allows manufacturers to use the same base and seat stays to produce frames of different sizes by trimming the monotube when building smaller bikes.
Another production advantage of wishbone seat stays is the absence of a seat stay bridge (the small tube connecting the two seat stays).
The aforementioned shortcuts may not seem like a lot when building a single frame, but during mass production, one less step saves a lot of effort and money.
- Less Mud On The Seat Tube
The monotube acts as a small mudguard reducing the dirt reaching the seat tube.
- Another Place For Accessories
You can mount clip-on seat post accessories such as rear fenders and lights on the monotube.
You also gain the opportunity to install or remove a seat post without having to take off the rear accessories.
- Stylish Appearance
Wishbone seat stays are rare, especially these days. Most people don’t even know that wishbone seat stays exist in the first place. Thus, by acquiring a frame with such an architecture, you will stand out.
- A Second Handle
When carrying the bike, one can use the monotube to lift the rear wheel. Some people will find that option useful and convenient.
The Cons
- Excessive Vertical stiffness (theoretically)
Some say that the monotube adds vertical stiffness to the frame without having a noticeable effect on the lateral stiffness.
Vertical stiffness is not desirable because it reduces the compliance of the frame and makes the ride harsher.
This problem is more pronounced when the bike is equipped with thin tires operating at high air pressure.
If the bike has wide tires running at low PSI, the suspension effect of the tire compensates for the vertical stiffness introduced by the frame design.
- Tricky Full Fender Installation
Regular full fenders normally attach to the seat stay bridge. As mentioned, wishbone seat stays don’t have one.
Also, the distance between the monotube and the tire could be quite small.
As a result, it becomes increasingly difficult to install a full rear fender, especially if a larger tire is used.
It’s still possible, though. I did it on my road bike by adding metal hooks made from a thick wire on each side of the fender. Then I secured the fender to the brake bolt via a zip-tie passing through both hooks.
Of course, if the frame uses caliper brakes and has enough clearance it should be possible to install the fender normally.
- Tricky Installation of a Rear Rack
Rear racks have stabilization stays normally connecting to the seat stays.
Wishbone seat stays do not come with rack mounts. Consequently, you will have to look for an alternative solution.
One of the possibilities is to install a seat post collar with rack mounts on it.
Another option would be to mount some sort of clamps directly on the monotube.
You Probably Won’t Feel a Difference
Here’s the deal – you won’t feel a difference riding wishbone seat stays. Anyone who claims otherwise is delusional.
Thus, it boils down to aesthetic preferences, primarily.
And never forget that the overall performance of a bike depends on its entire geometry (not just one segment), the used materials, the thickness of the tubing, the craftsmanship, the tires…etc.
The dissimilarities between wishbone seat stays and standard ones aren’t essential enough to create an easily perceivable difference.
Ultimately, it’s up to you to make a choice.
I got this frame for other reasons. And the wishbone seat stays were simply an aesthetic bonus. They weren’t my main focus.
Until next time,
Rookie
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