Darth Lefty 

Tom, are you thinking of the Future Shock, Shock Stop, or is there some other additional thing I've missed?

wolfchild

I am not a big fan of suspension on bikes for any type of riding. and even my mountain bikes which I use off road have a rigid fork. My body and my tires provide more than enough suspension.

noglider 

I don't know what it's called. A friend showed me his new high end Trek road bike. I don't even remember how it worked, whether it was in the stem or the headset.

gsa103

That would be Trek's IsoSpeed front decoupler. https://road.cc/content/tech-news/18...eed-decouplers
It lets the fork shift front/back slightly, moving the bars up and down to help take the edge off bumps. Specialized FutureShock is really just a miniature shock in the headtube.

To be honest, I don't understand the kinematics of how front IsoSpeed works. I guess the impact makes the wheel move backward by a few mm, causing the headtube to shift forward and the handlebars to drop as the front end rises to go over the bump. But it turns into a giant vector mess when you consider fork rake, stem angle, wheel size.

Darth Lefty 

That's interesting. The upper headset is in a trunnion, so it's not fighting the bending in the narrow part of the steerer.

That's basically entirely opposite of the point of going to tapered steerers in the first place.

grolby

I don’t think so, for two reasons. One, the deflection is fore-aft, while the deflection tapered head tubes are intended to resist is mostly torsional at a right angle to the direction of travel; two the lower headset and steerer are still anchored in place, and the steerer inside the head tube is essentially acting as a flex pivot, as you see in the rear suspension design of quite a few modern XC mountain bikes.

Darth Lefty 

Huh. Can you cite something? That makes no sense to me. The steering forces are dinky. The side forces are dinky. The cantilever from the handlebars to the steerer and from the wheel to the steerer must be on the order of a hundred ft-lb

Edit: you know what? Never mind. Trying to keep this thread light and useful and not bog it down

grolby

I don’t have a cite, sorry. I’m not a mechanical engineer and frankly I’m lazy. Believe me or not, that’s fair. All I can tell you is that to the best of my recollection tapered head tubes have always been sold on the basis of increasing steering precision by improving stiffness against torsion. From personal experience, it does make a difference, though personally I find it much more obvious off-road than on. Fore-aft stiffness isn’t really as relevant, I don’t think. And as I said, I think the fixed lower race should keep resistance to fore-aft flex very high.

Edit, sorry, I think I’m being unclear - my understanding is that, with the pivot point essentially being the middle of the steerer, an impact from below should induce fore-aft movement at the top of the stack but not at the bottom. Basically the lower race is still transmitting the force upwards, with the same vector as the rest of the fork. Does that make sense at all?

grolby

Believe me, I agree with you - intuitively, I think, surely the torsional forces on the frame from cornering are minuscule. But I can’t argue with the results. Again, if unclear, the plane of flex we’re talking about, here, is vertical. Imagine holding the head tube and seat tube of your bike and rotating them in opposite directions, as though you were going to twist them into a pretzel. That’s what tapered head tubes are primarily intended to resist, as I understand it.

subgrade

Short travel full suspension comfort bikes are a thing, although not very common. Ketller Alu Rad City Comfort is one model I know of, but therea are others too, I believe Giant also made one at some point in time. I think I've also seen an user here post a pic of his bike of such style recently.

Darth Lefty 

Right, but they're not really a category. You could maybe find one or two examples at a time. Cannondale had a Jekyll frame with a road wheelset, nearly 20 years ago.

Back on the topic of front suspension, this bike has a Head Shok, which was a Cannondale suspension fork in the 90's-00's. There were a variety of these, but they are no longer supported. There were many versions of the innards. Air/oil came first in 1992 but they did MCU on later less expensive versions. The placement limited the travel and to solve that they later moved the works outboard, and turned it into the Lefty fork.

Germany_chris

Those are more of European thing than American and they're getting a bit less common here too. While utility cycling is becoming more of a thing in the US we're still decades away from Europeans in that regard the good part is though that once were there companies have all the models we'll ever need.

Helldorado

For road commuting: it's not about the fork; it's all about the tire.

Darth Lefty 

I’ve been thinking about an addendum to this thread but I’m not sure how to quantify it. That’s control. It’s easier to talk about efficiency or comfort, and I suppose no one would like being told their favorite roadie bike is hard to control. (Prefer “agile!”)

Suspension forks improve control of the bike. I’m sure a debate could be staged, but I’ve watched my 6yo run his Hotrock with its little XCT fork up a curb and survive enough times, and remember how much worse it was on his 16er.

In the thread about “What did you find on the ground,” a common answer is “Myself.” I tried to see how many people had made this joke but ran into this problem:

FelixScout

This was an interesting read. Thank you.

fooferdoggie 

my e bike commuter came with the typical cheap suntour spring fork. I replaced it with the rockshox paragon gold and it works pretty well. mostly at higher speeds. but I can keep the tires at 70 psi they are 1.5" tires. the bike would beat me up in winter going 20+mph it does not move a huge amount.the bike bare is 52 pounds with my locks and one bag 70#