Threadless Steering Tube Extensions?

It sounds like this a MTB. Is the steerer tube Al or Fe? Is it 1'"or 11/8"? If it is 1 1/8" steel,
the sky's the limit. Your weight and riding style will determine the limits for Al. I once sleeved
an Al steerer w/cro-mo for a customer with few options. Tom

--
Bruni Bicycles "Where art meets science" brunibicycles.com
410.426.3420 (Pete Cresswell) <[email hidden]> wrote in message
"]news:[email hidden]...

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Maybe somebody with an engineering background can shed some light...

Seems to me like I read somewhere that the max height of a spacer stack

was

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something like 1.25 or 1.5 inches - anything in excess of that was

challenging

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the strength of the steering tube too much.

If that's the case, what's the diff between that and:

1) Really high riser bars - like 3". Isn't the leverage still there down

where

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the steering tube goes into the headset?

2) Steering tube extensions that clamp on to the existing protrusion -

same

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observation about the leverage still being there.

My agenda is that my riser bars are pretty high, and I've already trimmed

my

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steering tube so it's max stack is about 1.25". If I replace those

risers and

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want to keep the same bar height, I'll be faced with a choice between

getting

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risers that are just as extreme and getting, say, 1" risers and elevating

the

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stem attachment point (the stem's height is already max..).

Any thoughts besides getting a custom frame?
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PeteCresswell

(Pete Cresswell) said:

Seems to me like I read somewhere that the max height of a spacer stack was something like 1.25
or 1.5 inches - anything in excess of that was challenging the strength of the steering tube
too much.

That sounds like either a limit for carbon or aluminum steerers (possibly less for carbon) or
manufacturer's ass-covering. A steel steer tube is quite strong. It is stronger and stiffer than
other devices used to get several inches of rise, such as the swanlike 22.2mm diameter aluminum
Nitto Technomic stem, or the aluminum and steel quill riser stems that most early MTBs came with.

I'm pretty sure there are folding bikes out there with very long steerer extensions. Of course, they
aren't intended for big dirt-jumping, but I think you aren't planning on that.

Quoted message said:

If that's the case, what's the diff between that and:

Quoted message said:

1) Really high riser bars - like 3". Isn't the leverage still there down where the steering tube
goes into the headset?

Quoted message said:

2) Steering tube extensions that clamp on to the existing protrusion - same observation about the
leverage still being there.

RE/

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Is the steerer tube Al or Fe? Is it 1'"or 11/8"? If it is 1 1/8" steel, the sky's the limit.

1", Al. Marzocci X-Fly 100 fork.....
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PeteCresswell