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I'm building a bike up for someone and it's very special.... how is not important right now!!!
I've come across a problem where I need to tension a stem/aheadset combo, as in any normal bike, but I can't use any kind of top cap/SFN system (something else is on top of the stem!).
I'm sure I saw a tensioning system involving some sort of adjustable headset spacer once but can't find one now, can anyone help??
Can you use one and then remove? Once the stem is tightened up the top cap is redundant.
Can't you tension it, do up the stem, then remove the top cap?
adjustable headset spacer
called a ringo star.
http://www.ultimatesportsengineering.com/use-hardware/stem-and-headset/ring-go-star
but as jam bo says, you dont need to leave a top cap in situ once youve preloaded the headset bearings and then tightened the stem bolts to lock the tension in.
I had one like you describe. It sort of clamped onto the steerer and then could be rotated on a thread to effectively thicken it and tension the headset. Think it came from Halfords about 15 years ago. Not very helpful but they do/did exist.
I want to be able to adjust the headset afterwards if necessary without taking all the gubbins off the top that is in place of the top cap.
What "adjustment" is necessary?
Just in case the stem becomes loose.
Basically I am building a bike for someone who had one arm a lot shorter than the other. If I had loads of cash if just get something made up to fit but the budget is non existent.
Anyway what I plan to do is have a normal headset/stem/bar setup for the "normal" length arm and then use a quill adaptor to extend the steerer a bit (yes they do work and types they are reliable) so I can mount another short stem on top pointing backwards.
Each stem will have half a riser bar on it and one brake/gear lever.
If the headset needs tensioning after it's all done it would involve taking the quill adaptor out, installing a star nut and top cap, tensioning it back up, removing the star nut then replacing the quill adaptor.
I'd like some forks that have a steerer long enough so I could fit 2 stems on but I need about 250mm of steerer to do that.
I think I've more or less visualised what you're doing - haven't got a better idea but rather than use a star nut, why not an expanding bung* ? OK you still need to refit/reinstall it to take up play in the aheadset - but at least it's doable with an hex key, unlike a star nut.
*Hope head doctor and the like
edit, sorry - didn't read the first few posts and it's more or less what they said.
If you put a screw thread on the steerer there might be a way to fit an adjustable top race with some kind of locknut. I think you can get suitable components with 1 1/4 inch thread.
Acros type headset?
What about some custom bent bars? Custom motorbike places seem to charge about £60 for a set of custom bent steel bars. Will be heavy but I wonder how the weight compares to what you are looking to do.
Would a longer fork steerer with two regular ahead stems, one on top of the other not work?
There are others lke this and a friend had one which was like a two sawtoothed spacers which expanded when tightened u
Other option is again mentioned above. Thread the steerer and use a 1 1/8th threaded headset lock ring. That arrangement is used on raleigh twenties
Steerer tube extender (there's loads about but this one offers a load of height adjustment options);
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[url= http://www.excelcycle.com/montague-octagon-steerer-extender-height-adjust-qr-up-to-4-in.-long.html ]http://www.excelcycle.com/montague-octagon-steerer-extender-height-adjust-qr-up-to-4-in.-long.html[/url]
using a standard aheadset stem will give a lot more options with regards to stem length change as well.
Dia Tech headsets work without using an SFN. They have a clamp that expands down onto the top race wedge, under the stem after you tighten it up. [url= http://m.ebay.co.uk/itm/201250072513 ]Here's the clamp bit[/url]. Should do the job, depending on the headset you add it to. Might need a cone-type thing adding to it as well though.
breadcrumb - Member
Would a longer fork steerer with two regular ahead stems, one on top of the other not work?
POSTED 2 HOURS AGO # REPORT-POST
Yes that would be ideal but I can't find any suitable replacement forks for my budget.
I'd like some forks that have a steerer long enough so I could fit 2 stems on but I need about 250mm of steerer to do that.
Now your text last night makes sense Rob!
Is 220mm any good to you?
What sort of fork would be ideal?
I can get stuff..... 🙂
As above, I reckon a longer steerer fork would probably be a cheaper (and much simpler) option.
The bike he is using at the moment has some butterfly bars on it - he seems happy with those but I want to make something which will fit better. I have ordered some more butterfly bars to fit on this bike which I might try first before I buy anything else. If he doesn't use them I will - wanted to try some for a long time!
Found my old one. My old bike parts filing system works!
You tighten the upper/middle bit to the stem then rotate the lower part with the bearing to tighten the assembly. Once tight it is locked in place with an allen screw.
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Yours if you want it. Needs a clean and probably needs new bearings but it takes standard balls.
@nickjb,good one fella. I remember those YST things from a while back think they stopped making them AFAIK. 🙂
Tharsis XC?
http://www.pro-bikegear.com/en-gb/catalogue/components/81/stems/prss0308_main/tharsis-xc-stem
[url= http://www.chainreactioncycles.com/gusset-universal-headlock/rp-prod17766 ]Gusset Headlock[/url]
It's removable unlike a star nut. So your idea of a quill stem wound still work. There would be no need to remove the star nut each time.
I think too stems with really short stack height is your best bet.
Like this [url= http://www.evanscycles.com/products/dmr/swarm-stem-318mm-ec035608 ]Link[/url]