what you running on your 29er

looked at sheldons calculator and run through a normal 22:32 set up on 26 inch wheels is 17.9 gear inches – i could ride up a wall in that gear

a 28:32 set up is 22gear inches thats lower than i normally ride – 32:32 is normally as low as i go unless im feeling particularly lazy …. rare

a rohloff set up with 36:15 on a 29er with 180mm cranks is 19.9 gear inches at easiest – a 38:15 is 20.5 and 40:15 is 21.5

are any of these numbers relevant – am i going to jump on it and find that its much harder than the eq derailleur gear as folks keep telling me i will – ive ridden one for about 40 miles but didnt pay attention to the gearing on it at all – for all i know i coulda been on a 50 tooth ring !

brings me onto my next question – good quality SS 40 tooth rings for 4 bolt chainset …. not downhill rings and pref stainless steel !

I started off with 38:18 on mine then switched to 36:18 to try and keep out of the lower gears a bit more.

Edit.
I think it was an 18 on the rear but not 100% sure as I sold it quite a bit ago.

2nd edit.

Thinking again it was a 16 on the back.

Used a middleburn DH ring on the front.

I'm running a 40:13 at the moment and might change to a 38:13 or 40:16 undecided?

not really wanting to use a middleburn dh ring

prefer something stainless steel

surly only go up to 36 in 4 arm – have i many other options ?

for the dayshift – same question please

36 t Surly is the only stainless ring available and worth buying in 4 bolt. Have looked long and hard for alternatives in the past but to no avail.

I run 37:16 or 38:16 on mine. Gear range is fine and you still have gears at the bottom end of the range to climb like a MTBer offroad, not some technique-less roadie gear masher 🙂

38:16 is fine for MTBing, plenty enough at the top end to pedal (not like a lunatic) at 30 mph on the flat. I can't see the point in shedding the lower end to get bigger gears

gravel grinding is what i mostly want this bike to do Will i intend to ride the great divide race and im confident that is aidan can SS it on 32:18 (on a 29er ) i dont need the super low end – as nice as it would be at times it would tempt me to go slower and take it easy easy because i could. – im sure im faster racing on my SS than gears for this reason (course dependant) 36 at the front and a 13 and 15 for the rear and then what evers on it atm – i think 40:18 is on the bike i bought with a a rohloff its a middleburn dh ring and looks rancid

Ok, just bear in mind that the bigger the chainring the bigger the gaps between the gears as well. May or may not be an issue to you.

If you wanted to ride technical offroad climbs on the MTB I'd recommend 38:16 (or equivalent).

You can get a 13t sprocket from Rohloff which might be compatible with a 36t steel ring for the gear ranges you want. The 13 t ring is non reversible though and the wear rate on the smaller cog might offset the greater wear rate on the chainring anyway!

Will – think you're wrong there. All the shifting is at the hub so the chainring and cog make no difference to the gaps between the gears. It's always c500% overall/c13.5% per shift.

All you're doing is moving the overall gear band up and down. I've always run 38/16 on 26" wheels. I'm considering having a play with different sizes but haven't quite worked through the impacts. I figure larger cog on the back improves wear, larger on the front decreases clearance and alters impact on suspension (more imporant on single pivots frames). Anything i've missed? Thought about 36/16 (i like to climb the odd wall)

The percentage gap is the same but is that not a percentage of a different ratio to start with, and hence the absolute differences are not the same for different gear ratios? Just thinking out loud there. If that is the case, and I think it is, then there is not going to be much difference in a 38 or 40 tooth chainring I suppose.

Some info on here:

http://www.rohloff.de/en/products/speedhub/sprocket_ratios/

will – your sort of right but its the ratio that matters not ring size, because the rohloff just sees an input ratio (ie 2:1) it means the output ratios are a factor of that. So TR's choice of a bigger input ratio means his gear jumps will be a percantage of that input ratio, but as you say, it will be minimal difference.

TR – why so fixed on small sprockets? if i recall your going to be using this bike for everything, so why not run bigger rings and reduce wear? Surly rings are nice, tho obviously Thorn do some too (not sure about stainless tho).

As far as ratios go im sure i read somewhere that there were ideal ratios for reduced wear, somthing to do with factoring in areas of cahin stretch and ensuring the links of a chain only saw certain teeth on the ring/sprocket, this ensured you didnt add extra wear by trying to mate all the links of the chain to all the teeth. Somthing to think about.

surly only go up to 36 in 4 arm – have i many other options ?

Not SS, but the Renthal ones look nice

http://www.tritoncycles.co.uk/products.php?plid=m13b268s298p6632&rs=gb

STATO, yes I had perhaps oversimplified it by assuming keeping the same cog at the back. Small differences but definitely noticeable, recently switched back from a 37 (alps gearing) to a 38 and could tell straight away, although obviously I stopped noticing after a short while.

FWIW I had a Renthal ring and I wouldn't buy another. It wore quickly and was so thick (for DH RADNESS) that it threw the chainline out more than I would have liked.

not set on small sprockets at all id rather bigger – but 36T is the biggest surly ring i can get and thus my ratio would be 36:13 but id rather run a 40 upfront and a bigger rear ring to spread the wear better.

ground clearance not an issue im on a 29er that was designed to run gears thus a 44 outer …. what i do want is a stainless ring – experiance on my SS tells me that alloy – even good quality. lasts no time at all.

Sorry, i appear to be unable to read today. Will, your post was right, higher ratio equals bigger gear jumps. TR, yes surly dont do bigger than 36t, forgot that, why not 40t alu then? Salsa or Thorn maybe? Too slow!

You'll have to get alloy then. A reversible one will give some extra life I suppose. I would like someone to make a bigger 4 bolt stainless chanring but I suppose the demand is likely to just a bit too niche – otherwise someone would make one!

I did once get a 38 t steel DH ring that came with some cheap Truvativ DH cranks out of the workshop in the store I was working in at the time. Been looking for another ever since it wore out, but they don't seem to sell them. There are some really cheap and nasty looking steel rings for sale on eBay but they look like they're been robbed from a crappy shopper bike and are very thin.

salsa on my ss – 32t – lasted less than 3 months ! – part of that is my SS was my day to day mtb that i rode in all weathers on all trails and washed it once a week/month if it hadnt rained while i was out 😀 all it got was lube – obviously ill be trying to treat this bike a bit better as ill still have my SS to abuse but it still doesnt bode well for alloys longevity as a rohloff front ring

my on-one stainless did all last winter and came off and cleaned up to look like NEW

the real question is – whats cheaper …. replaceing alloy rings or replacing rear sprockets 😉

i ran a 14 tooth surly on my fixed wheel for 2 years commuting 20 miles each way 3 times a week – removed it about 4 months ago and it was hardly marked – slight puckering to the metal around the tooth but nothing a file wouldnt clean up – obviously thats road miles though