Originally Posted by
hillzofvalp
I could still waste a star nut and use the top cap for cosmetics, correct?
No, because that's where the bolt to secure the quill riser will go (you know the one in the first pic you posted). You'll still have a top cap, but instead of connecting to the star nut it will connect to the wedge at the bottom of the quill and it won't be used for tensioning.
Originally Posted by
Burton
(a) Sheldon specifically stated that even what he was doing was NOT recommended for 1in steering tubes or steering tubes made of carbon fibre. According to what I recall from this post, the OP has a 1in steering tube.
Yeah, but the reason Sheldon's mod is ill advised for a 1in steerer is because the seat clamp won't have enough friction to hold tight on the smaller circumference tube. The OP, however, will be maintaining bearing tension with either a normal threadless stem (in cascade with a normal quill) or a threaded race, all of which work fine with 1" steerers.
Originally Posted by
Burton
(b) The configuration that Sheldon put together was SIMILAR to what the OP whants to do. but there are CRITICAL diffirences.
For example, Sheldon installed a long sleeve with an integrated clamping system over a tube of continuous diameter. The OP wants to install a steering tube entender which will have a tapered profile in the area that would be clamped using a set-up like Sheldons and in the area that the spacer rings would fall according to how the OP first described his intentions. Neither or those could be considered `safe` because there would be too much chance for play.
And lets not forget the most import element -experience. Sheldon had the experience and background to analyze available components and identify and seperate workable parts combinations from potential problems. The OP is attempting to do something similar and is asking for help before even starting.
What happens inside the spacers is irrelevant. But what ARE critical differences are that the OP's setup will have less leverage to flex the headset area and uses better clamping mechanisms than a seatpost clamp, which makes it safer than Sheldon's setup. We can argue all day about the differences, but the point is that all the parts will function in their normal capacity, therefore it will work.
Sure, the OP doesn't have experience, but we do and mine says that what he's proposing is
at least as safe as what Sheldon proposed. How much experience do you have tensioning threadless headsets without top caps? I have plenty and have found they're rather forgiving.
Originally Posted by
Burton
So lets be clear. There`s a chance that the OP has a combination of parts that MIGHT make this feasable. That doesn`t change the fact that it`s neither cost effective nor ideal as a solution and any info I`m personally providing I consider similar to addressing an emergency repair with stop-gap solutions using whatever`s on hand.
Why isn't it cost effective? Sounds like he has all the parts except the threadless stem (which he's going to reuse once he upgrades) and the quill. So it's a choice between buying the quill vs buying a new fork, with the quill being cheaper (at the expense of being heavier and requiring more labor to install and maintain than a bonifide threadless fork).
Originally Posted by
Burton
A few years back at least one manufacturer was using these steering tube extenders 9With threaded headsets) in $1,500 bikes so my only real concern is preloading that bearing system. If it can be preloaded with a threaded locking nut independently of the steering tube extension then IMO safety issues have been addressed.
While it's true that quill stems aren't quite as secure as threadless stems, if they're secure enough to hold the handlebars than they're certainly secure enough to hold the bearing tension. After all, in the words of one bike manufacturer that doesn't spec top caps, "if you lose headset tension the worst that happens is you will need to adjust your headset, but if your handlebars come loose you're going to crash badly"
But, yeah, if given the option using the threaded top cap is probably better because there are fewer clamping mechanisms involved, but it's not a big deal.