How to raise head tube base?

sinjun

I'm building a road bike for my wife, having taken delivery of a bespoke titanium frame and forks from XACD. I must have miscalculated on my measurements since the top tube, which is supposed to be horizontal, slopes down a little towards the front - I think because the fork has a slightly unconventional rake (required to get the trail right for the given head tube angle).

Anyway, to rectify this, and to reduce the number of spacers above the head tube, I'm looking for a headset which has a large lower stack height, or possibly one with deep cups onto which I could put a spacer. Whilst these exist, e.g. Cane Creek S3 plus 5 http://www.canecreek.com/S-3-Plus-5-Headset.html, Chris King Steelset http://chrisking.com/headsets/hds_steelset I can't find one for the required 1 inch steerer size. The other option might be a head tube extender which I've seen http://www.flickr.com/photos/hardcore100/2456440897/ but can't track down.

Any ideas?

ride_whenever

how much do you need?

I had a FSA UFO with the needle roller bearings that did about 15mm or raising, but CRC aren't doing the 1" headset anymore.

ride_whenever

Longer a-c length possibly? Or put a 700cc front wheel on and a 650cc rear!

nicklouse

So let me get this right.
you now wish to change the frame angles by raising the headtube?
changing the trail etc. that you got the fork for .... (yes i know 5mm will only make a small change in headtube angle but my point is have you actually got the correct fork?).

sinjun

ride_whenever wrote:

how much do you need?

I had a FSA UFO with the needle roller bearings that did about 15mm or raising, but CRC aren't doing the 1" headset anymore.

17 mm or so would be good enough, 25 mm for dead level.

sinjun

nicklouse wrote:

So let me get this right.
you now wish to change the frame angles by raising the headtube?
changing the trail etc. that you got the fork for .... (yes i know 5mm will only make a small change in headtube angle but my point is have you actually got the correct fork?).

Raising the top tube to horizontal should bring the head tube angle to what I had intended - I think it's only about 0.6 of a degree for 10 mm anyway.

ride_whenever

that's going to be a big ol' headset... not sure you're going to find anything, just because of the size of the bearings necessary. The only suitable would be needle roller bearings methinks.

meagain

Having gone to the expense of a custom Ti frame, surely worthwhile having an "extender" like the one in your link machined to exact size needed? Should be possible even in titanium for not a vast amount of money! XACD would probably do you one.

nicklouse

sinjun wrote:

nicklouse wrote:

So let me get this right.
you now wish to change the frame angles by raising the headtube?
changing the trail etc. that you got the fork for .... (yes i know 5mm will only make a small change in headtube angle but my point is have you actually got the correct fork?).

Raising the top tube to horizontal should bring the head tube angle to what I had intended - I think it's only about 0.6 of a degree for 10 mm anyway.

and the effect on the trail?

i would be getting the correct fork myself.

Sorry i am trying to still see what the problem is? is it an incorrect fork or is it an incorrect riding position?

sinjun

nicklouse wrote:

sinjun wrote:

nicklouse wrote:

So let me get this right.
you now wish to change the frame angles by raising the headtube?
changing the trail etc. that you got the fork for .... (yes i know 5mm will only make a small change in headtube angle but my point is have you actually got the correct fork?).

Raising the top tube to horizontal should bring the head tube angle to what I had intended - I think it's only about 0.6 of a degree for 10 mm anyway.

and the effect on the trail?

i would be getting the correct fork myself.

Sorry i am trying to still see what the problem is? is it an incorrect fork or is it an incorrect riding position?

Incorrect fork for the frame if I want a level top tube - looks a bit odd sloping down. I was interested in designing a traditional looking audax bike (horizontal top tube) for a small woman (5 foot 1) whilst avoiding toe overlap. This involved a shallower than average head tube. Having ordered the frame I found I could not locate an off the shelf fork (1 inch steerer, 650c wheels, mudguard eyes) so I ordered one from XACD suitable for 650 wheels, taking the opportunity to calculate the correct rake to compensate for head tube angle and bring the trail back into conventional bounds. However, this greater than average rake has given the bike its forward slope - not necessarily a problem for riding position, more of aesthetic.

sinjun

meagain wrote:

Having gone to the expense of a custom Ti frame, surely worthwhile having an "extender" like the one in your link machined to exact size needed? Should be possible even in titanium for not a vast amount of money! XACD would probably do you one.

Hadn't thought of that - could be worth trying. They are pretty good at XACD in responding to requests but language can be a bit of a problem when trying to explain anything out of the ordinary....

nicklouse

Ok i now see what you are really wanting to do.

how much do you want to lift the frame off the fork?

As you may have other issues with the headset and an extender as the extender will have to be longer than the insert depth of the headset.

sinjun

nicklouse wrote:

Ok i now see what you are really wanting to do.

how much do you want to lift the frame off the fork?

As you may have other issues with the headset and an extender as the extender will have to be longer than the insert depth of the headset.

Yes, you're right - I would have to take into account insert depth of headset. I was thinking of about 20 mm.

nicklouse

Ok i have just been educated, (re read parktools with a 1" steerer in mind)

what i would have made up is an oversized bottom cup that will take a bearing for a 1" Integrated bearing.
then there will be no issues with the changing of the bearings and removing the extension.
I have something similar on some MTB's