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I was looking at lowering the gearing on my Alfine Inbred and thought a larger rear sprocket would be the easiest way to achieve this. The shop I spoke to said that I would be going past the Shimano guide Input Ratio of 2:1 by going for a 34/23 combo. I haven't been able to find much about this ratio on the Shimano web site and only seen some conflicting info elsewhere. It seems a bit high for a hub used on mountain bikes and given that I am already using a ratio outside this(34/20)will the 23 work nicely, explode the hub or kill me - any thoughts? Also does anyone run the Alfine without the rear chain guard- if so any problems (pattern sprockets without this guard seem available in larger sizes and cheaper)?
Thanks
Are you trying to catch mountain goats? That's a very low ratio, I'm on 32:20 and I'm a fat unfit get. There is an excel spreadsheet about showing you the ratios you get, not sure if it has the lowest bit thing included though.
You can use the rear without the plastic guide thing (which is pretty useless tbh), I run a nexus sprocket on my CX alfine to get the chain line shifted over a bit and it works well (the chainset trouser guard is no longer being destroyed).
TJ is yer man for this. He ran something like 22:20 at the puffer last year iirc
Thats quite low gearing at the top end, (gear inches on 26")
62.1
54.5
47.0
38.4
32.7
28.7
24.8
20.3
my rohloff at 36:16 gives me (gear inches on 29")
95.7
84.3
74.1
65.3
57.5
50.5
44.5
39.2
34.5
30.3
26.7
23.5
20.6
18.2
from
http://www.sheldonbrown.com/gears/internal.html
Saccade - no goat hunting yet but I tend to run low gears on all my bikes - 66" fixed on my Langster commuter. The Inbred is a gash "leave at work" bike which is only used for Surrey Hills stuff with workmates and not any great distance work. I was using bottom gear a lot the other night so thought a drop in ratios might be a good idea - I've never been in the position where a realy high gear has been required on this bike so am not bothered about loosing a bit at the top end of the range. Am on 34/20 at the moment and also on the larger size.
I thought shimano didn't publish a low gear limit - I have not been able to find one.
I am pretty sure 34 / 23 will be fine. I have been told 32 / 22 was the low gear limit.
I ran mine 22 / 18 at strathpuffer on the grounds that in the snow at 3 am you cannot have too low a gear and I wasn't going to worry abnout spinning out at 15 mph 🙂 it didn't break. I didn't hammer the pedals hard tho at all.
im running 32/22 on a fatbike for beachriding and it isnt low enough on very soft climbs due to the 29er outside effect of the tyres, was going to go 26f (inner ring) 18t rear for strathpuffer but didnt get an entry,will give you the chainring back TJ!,
with 32/22 it tops out on road and ideally id like a lower 1st and harder 8th gear, maybe the 11 speed will be better but quite expensive!
Been running mine with twin rings up front (22 and 36, 18 on the rear) and have now done around 3000 miles on this set-up with no issues.
I haven't been able to find a guideline for Shimano. My Rohloff is a 2:1 ratio.
I'm running a 32/22 on my Alfine on my fatbike so that 4th (direct) is equivalent to my usual winter gearing on a 29er. Couldn't imagine going lower than this - it wants to loop the loop in bottom.
TandemJeremy - Member
...I ran mine 22 / 18 at strathpuffer on the grounds that in the snow at 3 am you cannot have too low a gear and I wasn't going to worry abnout spinning out at 15 mph it didn't break. I didn't hammer the pedals hard tho at all.
You wouldn't need to hammer with that gearing. A light puff on the pedals would get you over anything 🙂
If you're 18stone and a gear masher, then running lower than the RECOMMENDED 1.6:1 ratio (not 2:1) might result in the internals stripping. It has happened to at least one guy I know of who posts on MTBR forums. He admitted that he's the wrong side of 18 stone though, and had put a 26T chainring on with a 22T cog on the back, and mashes the pedals!
So unless those criteria apply to you I wouldn't worry...
I've got 34/22 setup on mine, it's spot on for my 29er. I usually recommend 32/20 for most people running a 26" wheeled bike as a starting point, maybe go for a 34T ring if you find it too easy, a 21T cog if you find it too hard.
If you want the excel spreadsheet, then email me (mbonnes AT gmail DOT com)... It is I that created it, more than happy for you to have a copy. Plenty of others on here will hopefully attest to its usefullness, it works out all sorts of stuff from the gain ratio to gear inches to speed per given rpm etc... Just drop me an email and I'll send it to you...
Thanks for all the replies I think I'll give a drop in gearing a go and see how I get on.
[url= http://onehillside.com/hub.html ]there's a calculator here - hopefully slightly simpler than the Sheldon one[/url]
Nice one Woffle...
I wonder who did all the maths behind your online Calculator?!?! 😉
Incidentally, if you can be arsed to update it/change it, I've added the 11spd Alfine gear ratios in anticipation of its ever receding launch date...
howdo!
To be honest I'd completely forgotten about it - only noticed some hits from here a few months back. Quite happy to update (and I'll add a credit too) - if you mail the spreadsheet over I'll sort over the weekend.
YGM Woffle
Cheers fella
I ran mine 22 / 18 at strathpuffer on the grounds that in the snow at 3 am you cannot have too low a gear and I wasn't going to worry abnout spinning out at 15 mph
Given that is equivalent to a conventional 22/34 bottom gear setup (same as most people run in a full 27spd setup), and I've heard how bad the conditions are there, not a bad idea! Besides, like you say, spinning out at 15mph not really an issue if you're riding through mud and snow in the depths of a Scottish winter... Especially as rear tyre traction is likely to give out long before the clutch inside the hub mechanism is going to!