REVIEWS DEALS BIKESHOPS TRAILS

Helius AM and custom geometry

1273 Views 11 Replies 5 Participants Last post by gerard baste, Dec 16, 2008

gerard baste

Discussion Starter · Dec 14, 2008

Hi,

I went from a SantaCruz Nomad size L which I have broken (toptube).
I'm 183cm tall.

I'm looking for an Helius AM, with custom géométry.
I'm expecteed for a bike as stable as the Nomad if it's possible, but with more fun in the short an technical single track, and a better position to pedal.

So i imagine this géometry:

- Toptube 605mm (23.8)
- chain stay length 435mm (17.125)
- head tube length 125mm (4.92)
- seat tube length 480mm (18.897)
- seat angle 72°
- head angle 66.5°
- bottom bracket heigth to axle 17.5mm (0.688)

With a 36 Van RC2, it gives wheel base= 1140mm (44.88)

I think the rear tire will just touch the seat tube in maximal compression of the shock.

What do you think about it?

Sorry for my English, i'm French

Tanx! :thumbsup:

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The_Lecht_Rocks

· #2 · Dec 14, 2008

gerard - i am also 183cm tall and fit the large perfectly.
i run a 50mm stem.
i have long arms and legs and run 175mm cranks.
the large is very stable and very stiff.
a medium would be too small, as i demo'd a medium before ordering a large.
no need for custom geometry, unless you have shport legs ? short arms ?
the bike has less bob than a nomad, and way better quality of finishing, as well as more stability and a quicker steering response.
VPP is a waste of time ime. A good Horst link will always surpass VPP.

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The_Lecht_Rocks

· #3 · Dec 14, 2008

i also run a TALAS 36 up front, as the AM has adjustable rear travel, it makes sense to give yourself the option of running the bike at 130mm for trail centres, etc.

hope this helps ?

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gerard baste

Discussion Starter · #4 · Dec 14, 2008

The_Lecht_Rocks said:
gerard - i am also 183cm tall and fit the large perfectly.
i run a 50mm stem.
i have long arms and legs and run 175mm cranks.
the large is very stable and very stiff.
a medium would be too small, as i demo'd a medium before ordering a large.
no need for custom geometry, unless you have shport legs ? short arms ?
the bike has less bob than a nomad, and way better quality of finishing, as well as more stability and a quicker steering response.
VPP is a waste of time ime. A good Horst link will always surpass VPP.

I have also long legs (89cm), so the 73°2 seat angle make me afraid. My Nomad is 70°.

Also the 67°7 head angle seems to be a little bit to large for stability, with short chain stay length (430mm vs 445mm on my Nomad).

I don't want to have a bike like a Ellsworth Moment, very fun but not good for high speed i think..

Tanx for your help, I don't want to make a mistake

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chinaman

· #5 · Dec 14, 2008

it is very difficult to see how a custom geometry frame will handle ... will recommend that you demo a large frame AM and go from there ...

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The_Lecht_Rocks

· #6 · Dec 14, 2008

you're analysing too much - the bike is a trail devastator. seriously...

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Mr Bling

· #7 · Dec 14, 2008

I personally feel the geo custom is actually in pahse with the original biek and shouldn't upset the bike.

sounds balanced with an emphasis on high speed, could be wrong as Chinaman poits out but it seems ok

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The_Lecht_Rocks

· #8 · Dec 15, 2008

if you want more stability, then the FR is a better choice than the AM.
The AM's raison d'etre is to allow a range of trail rides with accelerated climbing and steering abilities, but still provide some of the beef available from the FR's DNA.
the AM definitely is quicker to turn and sharper than the Nomad of which you owned, but the new Nomad has revised geometry and a few details (1.5" headtube) which, on paper at least, don't quite add up.
as chinaman says, try a Large initially then go from there. custom geometry would be a last resort if the off the peg sizes / geom didn't fit your requirements.
from what you've described, i doubt the AM is the bike for you anyway. the geometry desired is mostly FR reaching ???

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The_Lecht_Rocks

· #9 · Dec 15, 2008

forgot to say that in asking for a bike to climb better (steeper seat angle required) and to turn better in the single track (steeper head angle, and less offset / fork rake), then stability is always going to be a trade off. it's impossible to add stability, without losing some element of sharpness / turn in rate.
you could lengthen wheelbase, but why would you want to ? the head angle would remain the same, and the rear couldn't track as well as the original design.
i sincerely hope you try a large demo first, and report back your findings. of course, try emailing nicolai and direct them to your requirements too..

let us know how you get on :thumbsup:

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Mr Bling

· #10 · Dec 15, 2008

I reply here on behalf of Gerad whose English is far from being perfect.

He wants a bike that can handle the mountains he lives in: no shuttles for him, he always pedals to the top and wants something fun to bomb downhill.

what he did was simply to make a lighter FR and makes the most of what the custom options enable. No doubt he could do with the stock L but he knows what he's after and what he likes.

and yet again, demoing a Large FR here in France is not an easy task!

I am the same size and same inseam and my numbres are real close to his if I were to go custom. But I'd be glad simply to ride a Nicolai

for info
Toptube 23.8 or 24
- chain stay length 17- head tube length 125mm (4.92)
- seat tube length 18.5
- seat angle 73°
- head angle 66.5°
- bottom bracket heigth to axle 17.5mm (0.688)
wheel base= 45

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0007

· #11 · Dec 15, 2008

hey hey, there are people I know here !

As far as lenght of the top tube, it is really personal.
I'm 1m85 and I'm running a 585mm top tube on my Helius FR. I've ridding a lot on a Helius FR in Large size (test bikes we had), but it felt too long and heavy to ride on our singles.
My Mpire is a Large and if I could go back, I'll change against a Medium size.

It really depends how you ride and what you're looking for. I mean even for my next CC I'm planning on getting a 585 top tube and this bike will be built to climb !

Back to the AM and the head angle, I have a 66° angle on my FR and it's not bad at all. Since you have 160 fork that can drop quickly, the Lyrik 2step, the 55 ATA, the 36 Talas, you can have a close angle for climbing and still have this DH look when going down.

At least that's what I wanted when I ordered mine. But I'm leaving in the mountains and my FR is being used mostly to go down. When I have to climb, it's a 10k climb and it's killing, what ever the geometry !!!

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gerard baste

Discussion Starter · #12 · Dec 16, 2008

Mr Bling said:
I reply here on behalf of Gerad whose English is far from being perfect.

cullééééééééééééééé!!!!!

rft:

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