ascherer 

ISO ideas...I've got an 8-speed hub on the way for a townie/commuter rebuild of my International. Before I start obsessing with searches, can anyone share their wisdom/experience for a suitable crankset? I probably need to go to a mid-to-low 30s chainring, and I prefer silver/alloy. Other than that I can be flexible. Pull the big ring off an old road set? Get something new? Thanks!

bwilli88 

https://www.ebay.com/itm/Stronglight...e/174080938465
This guy single speeded it

nlerner

Yeah, an 86 bcd crankset gives you lots of ring options. Plenty of contemporary Sugino models to choose from, too.

jcb3

Nervar Star

42 chainring seems fine to me with a 18t rear - about the same range as a 50x34 front - 13x28 rear

and way more quiet!

just finished this winter build and am liking it.

bwilli88 

My Alfine has a 19t cog on it and the online Gear calculator shows that anything smaller than a 38 will be a high torque situation and bad for the hub.



Bicycle Gear Calculator

stevel610 

Congrats congrats on the 8-speed. I used to have a Nexus igh 8. It was great.

Hudson308 

FSA Gimondi

ascherer 

Great suggestions, thanks. It’s a Sturmey 8, and 1st is 1:1. Has a 25 tooth cog so I’m aiming for mid-to-low 30s. @jcb3, that Pug looks great.

jcb3

Thanks

Mine is a Nexus 8, where 4th is 1:1

Salamandrine 

The period solution would have been TA 50.4 crankarms with one chainring. Still possible today with either new or vintage TA, SunXCD, VO, etc. FWIW. Nobody would have used a 30 something chainring though. It would have been 44t or around there.

I don't recommend using a double crankset with only one chainring, unless the outer one is replaced with a bash guard, or simply not used. The chainring bolts can tend to loosen up.

smontanaro 

Given what bwilli88 said about his setup, aren't you going to want a bigger chainring to avoid damaging the hub with too much torque? I am certainly no IGH expert, but I thought lower gears meant more torque. Here's a thread over on the bike mechanics forum about Sturmey 8's. Apparently the manual doesn't specify a minimum. Still, it would seem to be important which gear is direct drive (no load on the planetary bits, which I assume are what might break).

https://www.bikeforums.net/bicycle-m...m-gearing.html

I've read that Shimano does for (at least) the Alfine. Here's a thread about that. Minimum ratio for that hub seems to be 1.9:1.

https://www.bikeforums.net/bicycle-m...que-limit.html

Of course, IANAE (expert) and YMMV.

gugie 

What works? Whatcha got in your bin?

jackbombay

If every gear in the 8 speed sturmey is overdriven the hub has to be designed to handle a lot of torque so you aren't perpetually stuck in your low(est) gears.

What is the gear ratio for 4th and 5th on this sturmey?

ascherer 

It’s an XRF hub:
Gear 1 - 100% (Direct Drive)
Gear 2 - 132%
Gear 3 - 148%
Gear 4 - 169%
Gear 5 - 192%
Gear 6 - 220%
Gear 7 - 250%
Gear 8 - 325%

Seems like Sturmey sells a 30t crankset intended to go with these hubs. I’m pretty sure I don’t have anything applicable in the bin(s).

noglider 

I have a crankarm with an old 22T freewheel cog bolted to it if you want to try it.

But I think that given that your cog is 25T and you'll be using 700c wheels, a 34T chainring will give you a 37" gear which will get you up pretty much any hill. (34/25*27=37) You may not want to ride it in Vermont, but I bet that's not in your plans. Compare 37" with the lowest gears on your other bikes.

jonwvara 

A Stronglight 93 might look if you decide that a 37-tooth ring would be small enough. A few months ago I sold a 37-tooth ring to a customer who was planning to pair it with a Sturmey 8 hub--when I saw the title of this thread I thought it might be you, but evidently it wasn't.

ascherer 

@brianhamp Thanks for that link. Great info. @jonwvara Wasn't me. I have an unused PX-10 with a 93 (and, I believe, stripped extractor threads) and a handful of rings in storage. If one of 'ems small enough it could be a short-term option but Id have to get that crank off. Definitely wins the style category. @noglider No, I tend to take the Mercian to VT. Not that it's geared for it either!

Keep 'em coming, folks. This is great intel and I really appreciate it.

ascherer 

Starting to warm up to a 100 BCD 34. I could get silver Origin8 single arms easily enough and that wouldn't look too odd on that frame. .

noglider 

You could cover the chainring with a chainguard, and it would hide the puniness of the chainring.

ascherer 

Why do I hear that in Arnold Schwartzenegger's voice? "YA YOUR PUNY CHAIN VEEL ISS EMBARASSINK"

noglider 

bwilli88 

That Evilbay crank looks better than I thought looking at the 25t rear the gear chart likes a 30t chainring. Any chainring much bigger and the top end GI goes way up. A 34 or 35 tooth chainring gives some nice ratios in the middle 6 gears.


The difference between the Sturmey and the Shimano; the Sturmey wants big rear cog and small chainring and the Shimano wants smaller rear cog and bigger chainring with much the same ratios.

jcb3

Thinking outside of the box, you could go with a triplizer, (130bcd) that will get you down to 26t, then shave off the teeth on the triplizer to form a bash guard.

jonwvara 

I have no hesitation about flaunting the puniness of my chainrings. I figure that my freewheel cogs are so massive and manly that they more than make up for it.

ascherer 

Neal, can you point me to some of those? I'm not finding much that isn't on the 'Bay.