Measure twice......cut (gulp)

[Sprunghub]

I need to 'cut' the 'ahead' tube on the forks I have for the Marin. The bike came with a pair of RST forks & a multi-adjustable Zoom 'head', holding Marin bars.

The Zoom head was supported by 2 x 5mm alloy spacers. The fittings are standard Acor kit.

The 'stem' (steerer ?) on the Rockstar forks is in the region of 2.25" taller than the top of the Zoom 'head' when it is in place.

I think.....reading between the lines that I need to cut off more than just the 2.25" to allow the "cap" some compresson to tweak the bearings to perfection ? I can see that if I cut it 'flush' the flange of the cap will not be able to pull down as it will sit on the steerer tube ?

Is there a 'given' amount to exceed the 2.25" of off-cut ......

+.......before cutting the tube, I have the option now to increase / amend the spacer's under the head-set. Do I just stick to what I have (ie. 2 x 5mm = 10mm) or enter into complex calculus to decide the optimum spacing etc ? I have a 'pal' who tends to get stuff "off the shelf" & he suggests "leave well alone".....trouble is, once it's cut....with 10mm of spacing, if it need's 15 or 20mm, we're stuffed.

On all fronts, the Zoom adjusts up/down quite considerably, if needs be from -10 to + 40.

 

[jax13]

i would be tempted to get a set of small increment spacers (or cut down the 5mm ones if you can do it accurately), play about a bit and work out your ideal stem height before making the cut.

 

[Sprunghub]

Hmm....not sure how I / we tell what's "right" ?.....I've only ever been on a bike set up by the maker before

& the 'gap' between the top of the stem & the top of the head-set.....is 5mm about right ?

 

[Alex Creasey]

Another little trick I tend to do is if you have 10 mm worth of spacers under the stem, also add another 5mm spacer above it before the ahead cap. That then gives you a little more playing space to get the feel and move things around (not alot I know but it all helps).

 

[feetabix]

A few years ago I cut a new carpet for my living room, using the old as a template......I placed them back to back to get a better surface to cut and ended up with a mirror image......doh!.....lesson learned!.....use spacers to get a feel first and double double check!!!!!......good luck!....

 

[Sprunghub]

Ok - all noted.....have some more spacers - 15mm's worth - & another "star" thing, as I'm guessing I won't have much luck getting the other one without fubarring it - especially with my track record.

Seat is sorted...as suggested on the 'other' thread, it's a 27mm dia. post.

Begins to look 'ok'.

 

[02gf74]

A few years ago I cut a new carpet for my living room, using the old as a template......I placed them back to back to get a better surface to cut and ended up with a mirror image......doh!.....lesson learned!.....use spacers to get a feel first and double double check!!!!!......good luck!....

hahaha double then triple check.

few years back I wanted to fit three rooflights (dome windows) to my garage roof.

marked it all out, measured twice ..... then went and sawed out the piece in between two adjacent rooflights. :? boy did I feel sick. :evil:

 

[jax13]

few years back I wanted to fit three rooflights (dome windows) to my garage roof.

marked it all out, measured twice ..... then went and sawed out the piece in between two adjacent rooflights. :? boy did I feel sick. :evil:

that is legendary!

 

[We_are_Stevo]

What no-one has actually said is; set your seat up to the correct height (heel flat on pedal at full extension to give mandatory slight bend in knee when pedalling...) whilst mounting stem on uncut steerer - start with NO spacers (my preference) then add spacers until you're comfortable with the position. Then REMOVE one 5mm spacer and mark the steerer at the top of the stem - this is your cut line. When you have cut your steerer nice and straight and chamfered the edges with a file put it all back together and you will have a nice, neat 5mm gap between the top of your steerer and the top of your stem. Insert your new star nut 10mm into the top of the steerer, tighten up the top cap so there's no play in the bearings, tighten up the stem clamp bolts and you've just set up your bike better than any shop ever did for you

 

[Sprunghub]

'Tis done....'tis good

Thanks for all the help/advice.......