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80t chainring on the SX

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80t chainring on the SX

Postby one_half_3544 on Sun Sep 03, 2017 2:51 pm

Has anyone tried to install the 80t chainring (from SD, for example) on the regular strida SX?
My current understanding is that it should be pretty straightforward and would require the chainring itself, obviously, a new belt and possibly a new set of cranks (strida sx has 4-bolt cranks and sd has 5-bolt it seems)).
What are the other options for procuring 80t chainring?

It is just that the 100t on SX gives a gear ratio that is a little bit too high for me, especially for touring. And, while always thinking that SD low gear is really low, I've the checked it with the gear calculator recently and found out that it would be the same as my mostly used 'urban gear' on the mtb =)
So I would like to upgrade.
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Re: 80t chainring on the SX

Postby Blackstridaaustria on Sun Sep 03, 2017 6:23 pm

Maybe you can find a chainring, but you may have trouble to get matching cranks.

Btw, your development now is about 4,4 m - and you want a bit lower.
But 3,5 m is not really a bit - that's 20% :|
You are sure with the Mtb ratio?
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Re: 80t chainring on the SX

Postby one_half_3544 on Mon Sep 04, 2017 9:44 am

Well, yes. My mtb is dahon Cadenza xl with 39t/18t chainring/rear cog. This, with 2" tyres gives 47.5 gear inches in the 4th gear (according to sheldon's calculator). This gear gives me 20-22km/h with comfortable cadence. 25 km/h if I spin really fast =)

Strida SD with 18" wheels has 48 gear inches according to this post. So it looks like what I need.

I would have preferred something closer to the original strida 5 gear (53 gear inches), but, while finding/ordering bespoke chainring (90t?) might be an overcomable problem, finding a source of custom-length belts would be much more troublesome..
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Re: 80t chainring on the SX

Postby Blackstridaaustria on Mon Sep 04, 2017 1:40 pm

Forgot the Alfine, shame on me...

Edit:

Yes of course you are right.
I mean there's no chance to get a custom belt.
All you can do is try to find an 80 teeth wheel and matching crankset.
The belt is not a problem for Schlumpf/ATS drives.
Maybe you need spacers for the beltwheel.

Edit II:

Chain drive is not an option for you?
Maybe one could use 62:20 or 58:19 :?:
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Re: 80t chainring on the SX

Postby one_half_3544 on Sun Sep 17, 2017 6:24 pm

No, I actually like the belt (or, rather, I don't like the chain maintenance =)

Ok, so far the best offer for is from https://bikegang.ecwid.com/

So the only thing left now is to find a 110mm bcd cranks w/o chainrings (and probably singlespeed ones, to ensure straight chain line ?)
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Re: 80t chainring on the SX

Postby Blackstridaaustria on Sun Sep 17, 2017 7:47 pm

one_half_3544 wrote:...and probably singlespeed ones, to ensure straight chain line ?...


Not even with a single speed type can be ensured that the chain line is straight - and that's what I meant already above with the spacers!

It may also happen that you need custom spacers and/or a modification of the beltwheel depending on the spider of the new cranks.
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Re: 80t chainring on the SX

Postby Chester_Tan on Wed Jan 24, 2018 9:31 am

I have tried that gearing on an SD (2 speed 80T chain ring.) with 18" wheels.

You'd be slower than a single speed with 16" wheels.
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