What chainring and rear cog for Rohloff?

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tommydog
Posts: 278
Joined: 11 Feb 2017, 6:48pm

Re: What chainring and rear cog for Rohloff?

Postby tommydog » 19 Dec 2020, 9:27pm

rotavator wrote:
but my main concern is finding at least a 48 tooth front chainring that will work with the Herbie in 104 BCD. What options do I have, as I heard the Thorn is too thick for the Herbie and the Surly only goes up to 36 tooth in 104 BCD.

Spec TA do a 48T 104 BCD 4 bolt chainring:

https://www.spacycles.co.uk/m8b0s113p2754/SPECIALITES-T-A-104-BCD-outer-42-50t

I don't how thick it is I could check some of mine tomorrow


Thanks for the suggestion, but are you sure it will work with a Rohloff? It does not say single speed on the webpage, but "Compatible 8/9 speed" I would use it with something like this:
https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1

Brucey
Posts: 42208
Joined: 4 Jan 2012, 6:25pm

Re: What chainring and rear cog for Rohloff?

Postby Brucey » 19 Dec 2020, 9:48pm

that TA chainring is a double outer, has short teeth and has shift aids on it. IME such chainrings don't work well in SS/IGH applications (they are designed to help the chain off...) and you certainly can't expect a chainglider to work with them; the shift pins would probably tear it to bits.

TA make a whole load of stuff which isn't widely available in the UK (maybe a TA stockist could order it specially?). They make 104 BCD chainrings for SS/Rohloff use and they only go up to 44T. However they also do 104 BCD 'blade evo' chainrings for BMX and they do go to 48T and beyond (41-50T in 1T intervals);

Image

https://specialites-ta.com/bmx/330-1533-bmx-plateau-specialites-ta-bmx-blade-evo-104-specialites-ta-pl45104119.html#/22,denture,41-dts

One of those would do the job?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

tommydog
Posts: 278
Joined: 11 Feb 2017, 6:48pm

Re: What chainring and rear cog for Rohloff?

Postby tommydog » 19 Dec 2020, 10:11pm

Brucey wrote:
TA make a whole load of stuff which isn't widely available in the UK (maybe a TA stockist could order it specially?). They make 104 BCD chainrings for SS/Rohloff use and they only go up to 44T. However they also do 104 BCD 'blade evo' chainrings for BMX and they do go to 48T and beyond (41-50T in 1T intervals);
https://specialites-ta.com/bmx/330-1533-bmx-plateau-specialites-ta-bmx-blade-evo-104-specialites-ta-pl45104119.html#/22,denture,41-dts

One of those would do the job?

cheers


Thanks for the suggestion. This is probably a stupid question, but on that website, some of them have dts abbreviations and others just have T abbreviations - what is the difference? Would they both be suitable for a Rohloff and the hebie chainglider?

Also I wonder if there is any big difference between the BMX stuff and the marketed Rohloff stuff? I did use a BMX chain once on my Rohloff and it seemed to work well.

Brucey
Posts: 42208
Joined: 4 Jan 2012, 6:25pm

Re: What chainring and rear cog for Rohloff?

Postby Brucey » 19 Dec 2020, 10:17pm

I have always assumed that dts is an abbreviation for 'dents' and that T is for teeth, so they mean the same thing.

I would expect the running qualities of a BMX ring to be no different from any other SS type chainring, and that differences would be confined to style and strength of the blank. So there is a chance it is thicker, away from the teeth, like the thorn one is....? I don't think I have ever had one of these in my hands and if I had I wouldn't have been looking at exactly how thick the blank was. Having said that, I have had a thorn reversible chainring and that did strike me as unusually thick.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Billy007
Posts: 57
Joined: 15 Apr 2020, 8:56am

Re: What chainring and rear cog for Rohloff?

Postby Billy007 » 20 Dec 2020, 3:10am

tommydog wrote:With my 26" wheel Rohloff touring bike, I currently ride with a 42 tooth chainring at the front and a 16 tooth cog at the rear. I know a lot of people have this setup, but I find I want something a little quicker. I tend to tour very light and have never used any of the gears 1-3, even on very steep hills.

What combination would people suggest? Whatever I choose, I will want to stay with it for a while, as money is tight at the moment and I can't really justify experimenting too much. I have decided to do this now, as my current chainring is worn out, so it's a good time to do this.

Also what is the best value to quality chainring to buy? I purchased the Thorn chainring before:
https://www.sjscycles.co.uk/chainrings/ ... nch-black/

Along with this:
https://www.sjscycles.co.uk/sprockets/1 ... ket-steel/

Are the above products still the best bet? About 50% of my riding is offroad so it needs to cope with mud / grit relatively well.


It would be helpful if you stated what bike you actually have, what tyre width you have on your bike and crank length? Also what sort of cadence you like to ride at? Are you a grinder or spinner? What is your height and weight? Are you a tall big guy built like a sprinter or a diminutive mountain goat type of guy best suited to climbing? I have a feeling you might be a big powerful grinder riding at quite a low cadence. I am more mountain goat than a big heavy rugby player frame.

If you typically ride at a cadence of say 90-95-110 cadence in gear 14 on a 42x16 with 26"wheels and 1.75" tyres this gearing will take you to over 30mph! I like to think I am still a strong cyclist but seriously the only time I get into gears 13 and 14 is down a steep hill or a very very strong following wind. Most of the time I am riding in 10-11 on the flat in fairly undulating terrain mostly gear 11, sometimes 12 if I am riding faster 20+mph, although the gear markers have now worn off my twist grip, carrying moderately heavy rear panniers. On tour I have never not been able to get up a steep slope, hill or mountain pass even 30% in bottom gear, nor have I found I needed a higher top gear to change into. I would rather have the lower gears for when I am crawling up an incline and my legs are screaming for lower gears to winch me and my bike up the gradient.

However I have a spare 17T rear sprocket, but have never used it yet. I have a spare Thorn 39T front chain ring, but have never had need to use it yet. Currently I use a 5 arm 130 bcd FSA Vero chainset with 172.5 cranks iirc. I will have to check. I have a Hebie Chainglider fitted as well. At first it was a PITA to get to sit properly and not rub due to it being a little too tight on the Thorn 5mm 7075 42T front chain ring. At the time I bought their front chain ring and Hebie Chainglider, SJS marketed it at as fitting. They no longer do as their chain ring is very slightly too thick for the chainglider. But I managed to make it fit better by trying to widen the Chainglider casing around the chain ring part using hot water and wedges over night to splay it out slightly. This seemed to partially work, but nevertheless in the years since the Thorn chain ring has now worn where it was initially in contact with the front portion of the plastic guard. Now the front chain ring doesn't make contact with the plastic housing of the chain guard and all is fine and quiet. I did look at getting a Surly front chain ring but they are steel and heavier. I was trying to keep my bike set up light. The Thorn front chain ring is 7075 aluminium and reversible and high quality. They were only about £34 when I bought mine.

The Thorn front chain ring is reversible which I have not yet had to do as it still looks like new in terms of wear on the teeth despite having about 30k miles on it which is testament to the protective performance of the Hebie Chainglider. Of course there is the very slight wear mark scoring the edge where it rotates inside the chain glider. I'm not bothered by this as I now keep the Chainglider on the whole time. The first year I took it off in the summer. Waste of time, the chain still got dirty and crappy so I now keep it on the whole time. On reflection I really like the Hebie Chainglider cover. At first it was a PITA now it is fine and wouldn't ride without it.

As for your gearing query I would ask what sort of cadence and power outputs are you pushing in gears 11 and above as I mention above 42x16 in gear 14 is more than high enough on a flat road with little wind to get you above 30mph! Given you have a touring bike with 26" wheels this is some feat to be habitually spinning out.

I tried a friend's bike the same a Troll with 26" wheels but with 1.5" tyres and they had their bikes built with a 44Tx16 set up, no Chainglider so chain needed more maintenance, but the gearing was so high. I didn't get much above gears 9-10. I stuck it in 14 and it was like riding a track bike. I could only just about turn the pedals at about 17-18mph in top gear. I know you would typically be riding faster when you did change into gear 14 but I thought "Jeese that's high!" when would you ever use the higher gears let alone gear 14 except when going down a steep mountain pass when you'd probably be doing well over 35-40mph anyway and free wheeling and likely braking trying to slow your bike down not speeding up before you lost it on a hairpin bend!

My suggestion to you would be to fit a Thorn 7075 44T 104 bcd front chain ring and see how you go with that. If you like it then fit a Hebie Chainglider although initially you might have rub so will have to open up the channel a bit as I did and expect some wear on the chain ring but it isn't that much and frankly nothing to worry about if you have the chain glider fitted the whole time anyway. I wouldn't go above a 44T front chain ring as that is frankly too highly geared but each to their own. Your knees would likely suffer premature failure if they haven't already. If you go for a chain ring other than the Thorn one you have linked to you need one specific for a single speed. You don't want a chain ring with the pins, ramps and cut outs in that are present in chain rings used on double and triple chain sets. Just pointing this out. Sorry if I am stating the obvious.

With respect to chain I use a KMC X1 silver single speed and Rohloff specific chain (now discontinued) with the supplied quick link which has never ever broken so I don't know what you are doing with your chains? Is the chain line for your bike set up correct? It should be around 54mm. Each chain lasts nearly 20k mile before it gets to the 1.0 mark on my Park chain checker tool. I've only had to change the chain once.

Depending on the bike you are riding and available clearance using a larger 700c wheel might be another option using a wider and higher tyre akin to a 29" set up to raise gearing but of course this will not be a cheap option as there would be considerable cost perhaps something that you are unable to do at present given you have stated money is tight. When isn't it!

I hope my thoughts are of help to you and you are appreciative of the time I have taken to give you them. I do actually ride a bike with the gearing and components you are asking about and have the experience of how they perform as opposed to others on here with seemingly key board experience only.

tommydog
Posts: 278
Joined: 11 Feb 2017, 6:48pm

Re: What chainring and rear cog for Rohloff?

Postby tommydog » 20 Dec 2020, 9:48am

Billy007 wrote:At first it was a PITA to get to sit properly and not rub due to it being a little too tight on the Thorn 5mm 7075 42T front chain ring. At the time I bought their front chain ring and Hebie Chainglider, SJS marketed it at as fitting. They no longer do as their chain ring is very slightly too thick for the chainglider. But I managed to make it fit better by trying to widen the Chainglider casing around the chain ring part using hot water and wedges over night to splay it out slightly. This seemed to partially work, but nevertheless in the years since the Thorn chain ring has now worn where it was initially in contact with the front portion of the plastic guard


Thank you for this feedback, it is really helpful. In all honesty, it sounds like a nightmare. I don't want to be messing about trying to stretch things out in hot water with wedges etc. I just want something ready to fit out of the box. On this basis alone, I am going to rule out the Thorn and look for a thinner chainring, as I really would like to try the Hebie Chainglider. I don't know if you realise, but I am currently running a Thorn and have been happy with it, but it's now come to the end of its life and will need something thinner for the Hebie.

I do tend to go through chains quite quickly, but then again my chains get regularly caked in mud, as I do a fair few bridleways etc. Not really steep mountain bike stuff, but nevertheless plenty of mud and grit. Most of my riding is quite local and averages about 65 miles a ride, but I do like speed. But then again I always stop for at least an hour to visit a pub. Downhill, it would be nice to have something that would take me over 40 mph.

As for my build, I am around 5'7" and around 14 stone. Years ago I used to do bodybuilding, but these days I am carrying a few extra pounds! As for riding style, I am definitely a grinder. As I say, I hardly ever use gears 1-3, even in the Scottish Highlands.

So with all this in mind, I am minded to try a 48 chainring, but it needs to fit the Hebie Chainglider out of the box. That does not leave many options, as I need 104 BCD. What do you think about this that another user posted:

TA BMX Blade Evo 104 Specialty Chainring
https://specialites-ta.com/bmx/330-1533 ... ure,41-dts
Last edited by tommydog on 20 Dec 2020, 11:02am, edited 1 time in total.

tommydog
Posts: 278
Joined: 11 Feb 2017, 6:48pm

Re: What chainring and rear cog for Rohloff?

Postby tommydog » 20 Dec 2020, 9:49am

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Last edited by tommydog on 20 Dec 2020, 11:01am, edited 1 time in total.

tommydog
Posts: 278
Joined: 11 Feb 2017, 6:48pm

Re: What chainring and rear cog for Rohloff?

Postby tommydog » 20 Dec 2020, 11:01am

tommydog wrote:
Brucey wrote:I have always assumed that dts is an abbreviation for 'dents' and that T is for teeth, so they mean the same thing.


I did think that, but I can't understand on the same website listing why some are labelled dts and others T.

GrahamJ
Posts: 13
Joined: 18 Nov 2020, 8:15am

Re: What chainring and rear cog for Rohloff?

Postby GrahamJ » 20 Dec 2020, 11:41am

I don't have a Rohloff, but have been thinking about getting one over the last couple of months. I've adjusted my current bike to a 15-80 range, closely matching the range of a Rohloff, and using that for a month or so. It's about right for me and the cycling I do. If I have understood the previous comments correctly (especially Brucey's), then for such low gearing, a Hebie Chainglider is not possible. Is that right?

Brucey
Posts: 42208
Joined: 4 Jan 2012, 6:25pm

Re: What chainring and rear cog for Rohloff?

Postby Brucey » 20 Dec 2020, 11:48am

GrahamJ wrote:I don't have a Rohloff, but have been thinking about getting one over the last couple of months. I've adjusted my current bike to a 15-80 range, closely matching the range of a Rohloff, and using that for a month or so. It's about right for me and the cycling I do. If I have understood the previous comments correctly (especially Brucey's), then for such low gearing, a Hebie Chainglider is not possible. Is that right?


you don't say what size wheels you are using. AFAICT chaingliders are made in different sizes to fit chainrings 38T, 42T, 44T, 48T. The rohloff rear section (for use with splined sprockets) is compatible with 15,16,17 tooth sprockets.

Thus 38/17 is the lowest ratio which allows a chainglider to be used with a rohloff, and with with 26" wheels gives gear ratios of ~15.6" to about 81"

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

GrahamJ
Posts: 13
Joined: 18 Nov 2020, 8:15am

Re: What chainring and rear cog for Rohloff?

Postby GrahamJ » 20 Dec 2020, 12:18pm

Brucey wrote:
you don't say what size wheels you are using. AFAICT chaingliders are made in different sizes to fit chainrings 38T, 42T, 44T, 48T. The rohloff rear section (for use with splined sprockets) is compatible with 15,16,17 tooth sprockets.

Thus 38/17 is the lowest ratio which allows a chainglider to be used with a rohloff, and with with 26" wheels gives gear ratios of ~15.6" to about 81"

cheers


Thanks. I would get a new bike, so it could be 26" wheels, but I made it 26*(38/17)*.279 = 16.2 (which I find irritating).

ID Works's All Rohler (https://www.idworx-bikes.de/product/all_rohler) can have a non-Hebie chain guard , which I presume works well (at a price), but I don't know what gearing is possible, or if they'd sell just the guard.

Brucey
Posts: 42208
Joined: 4 Jan 2012, 6:25pm

Re: What chainring and rear cog for Rohloff?

Postby Brucey » 20 Dec 2020, 1:11pm

your calculation assumes that the wheel size is actually the nominal 26". It is only this big if you fit the fattest tyres for which those rims are designed, more or less. My calculation assumed 35mm tyres on 559 rims, hence the discrepancy.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Billy007
Posts: 57
Joined: 15 Apr 2020, 8:56am

Re: What chainring and rear cog for Rohloff?

Postby Billy007 » 20 Dec 2020, 1:32pm

tommydog wrote:
Billy007 wrote:At first it was a PITA to get to sit properly and not rub due to it being a little too tight on the Thorn 5mm 7075 42T front chain ring. At the time I bought their front chain ring and Hebie Chainglider, SJS marketed it at as fitting. They no longer do as their chain ring is very slightly too thick for the chainglider. But I managed to make it fit better by trying to widen the Chainglider casing around the chain ring part using hot water and wedges over night to splay it out slightly. This seemed to partially work, but nevertheless in the years since the Thorn chain ring has now worn where it was initially in contact with the front portion of the plastic guard


Thank you for this feedback, it is really helpful. In all honesty, it sounds like a nightmare. I don't want to be messing about trying to stretch things out in hot water with wedges etc. I just want something ready to fit out of the box. On this basis alone, I am going to rule out the Thorn and look for a thinner chainring, as I really would like to try the Hebie Chainglider. I don't know if you realise, but I am currently running a Thorn and have been happy with it, but it's now come to the end of its life and will need something thinner for the Hebie.

I do tend to go through chains quite quickly, but then again my chains get regularly caked in mud, as I do a fair few bridleways etc. Not really steep mountain bike stuff, but nevertheless plenty of mud and grit. Most of my riding is quite local and averages about 65 miles a ride, but I do like speed. But then again I always stop for at least an hour to visit a pub. Downhill, it would be nice to have something that would take me over 40 mph.

As for my build, I am around 5'7" and around 14 stone. Years ago I used to do bodybuilding, but these days I am carrying a few extra pounds! As for riding style, I am definitely a grinder. As I say, I hardly ever use gears 1-3, even in the Scottish Highlands.

So with all this in mind, I am minded to try a 48 chainring, but it needs to fit the Hebie Chainglider out of the box. That does not leave many options, as I need 104 BCD. What do you think about this that another user posted:

TA BMX Blade Evo 104 Specialty Chainring
https://specialites-ta.com/bmx/330-1533 ... ure,41-dts


With a 48T chain ring on a 4 bolt 104BCD spider crank I would be concerned about flex of the chain ring when pedalling hard under load. You have said you are more a grinder than a spinner so I am guessing you might put a lot more power and create more torque around certain parts of each revolution of the pedal which might cause this set up to flex more. Note I say might. Also you want to get a thinner chain ring so you can use the Hebie Chainglider without it rubbing which means the chain ring might be more susceptible to flex as it is thinner. Iirc the Surly steel/ stainless steel front chain rings are slightly thinner, but heavier and are a lot more expensive (double the price iirc) than the Thorn chain rings.

My first thought from what you have described of your set up and style of cycling would be to have a crank and chain ring that will be as stiff as possible so I would suggest you do get another Thorn chain ring if ONLY to see whether the 48T front ring gives you the higher gearing that you are seeking and is not too high which I feel it might well be. There might be a bit of trial and error. You can do only so much looking at gearing charts. The test will be when you come to ride your bike. I feel this would be the cheapest option for you as a starter. Don't buy a chain cover until you are happy with the gearing. The Thorn chain rings iirc are 5mm thick and pretty robust. I should imagine that probably the most robust of chain rings, but don't have any hard evidence or data to support this although other posters might be able to offer further advice in respect of this aspect. My Thorn 42T chain ring has never felt like it is flexing but then it is a 5 arm 130 BCD ring and smaller in size than the one you are wanting to buy. Also I tend to spin more than grind and use the gears more so I might be exerting lower stresses through the cranks and drivetrain and therefore creating less force thus flexing of the chain ring. The stiffness of the bottom bracket area of the frame may then also come into play. But there are more technically qualified people on here to answer rigidity issues for you here than me.

Anyway my suggestion is you get both 44T and 48T Thorn chain rings. See how you go with it. They are showing as £37.99 plus postage from SJS which isn't a huge price really. If you buy two at the same time you save £5.50 on postage as well compared to buy them individually. I see they also do 45T and 46T rings as well.

If you find a ring size isn't giving you the gearing you are seeking i.e. it is too high which I fear it might or indeed still too low then you can sell the ring(s) here or on Ebay for half price and you've only lost about £20 which isn't that bad. Alternatively you look for a COMPLETE new chainset but in a 5 arm 130BCD which might well be stiffer than a set up with a 4 arm crank 104BCD with the larger 48T chain ring. This is going to be more expensive but fairly easy to do. I don't know what BB whether HollowTech 2 or square taper you have on your bike? But you would also need to find a single speed chainset or a double chain set where you can get a chain line of 54 mm for the Rohloff hub as this might change with a new chainset. I think the FSA Vero chainset I have is a double but I use the outer ring with the 42T Thorn chain ring that gives a 54mm or there abouts chain line. My chain chain ring and rear sprocket seemed pretty in line when I checked them when I set my bike up plus I measured from the centre line of the bike on both axles and calculated the chain line.

For me the gearing and issues of rigidity of the chain ring come before the chain cover.

You might want to alter your cycling style. I don't know what cadence you ride at but if it is really low and you are pushing really heavy gears this might be a reason your chains wear out quickly and why they break? If you cycle at a higher cadence then this generally creates less stress on the drive train components and your knees! Maybe you should get a cycling computer with cadence sensor to see what you are doing. Pushing heavy gears is not good for your bike or you. I think the 44T or 46T would give you the higher gearing you are seeking but still be stiff enough on your 104 BCD 4 arm crank. I feel a 48T front chain ring is too big.

Do you have a Thorn bike? Raven or Nomad or something else? You said you have the Thorn chain ring. If you have a Thorn bike then they might be able to advise of the suitability of components to achieve the gearing you want, if of course you bought the bike new from them.

For chain covers may be you could look at something else which maybe wider allowing you to use it with the Thorn chain ring such as a Pashley or a Raleigh cover or maybe go onto a few German websites as they produce a lot more very good utility bikes than we do in the UK? Just suggestions. Yes it does seem strange that the Hebie Chainglider is quite narrow. You would have thought Thorn/SJS could have got them to make a wider one given they sell quite a few Rohloff equipped bikes. But I guess the numbers that SJS sell are a small fraction compared to the huge volumes sold in the German market. I don't know if certain Ebikes, horrible things, have fully enclosed chain guards, that could possibly fit or be adapted to fit your bike? Just guessing. You might have to make compromises some where.

Has your bike or just the current front chain ring reached the end of it's life? If the former I wouldn't spend a lot of money on your current bike. Put all your money into something newer.

Billy007
Posts: 57
Joined: 15 Apr 2020, 8:56am

Re: What chainring and rear cog for Rohloff?

Postby Billy007 » 20 Dec 2020, 2:13pm

GrahamJ wrote:I don't have a Rohloff, but have been thinking about getting one over the last couple of months. I've adjusted my current bike to a 15-80 range, closely matching the range of a Rohloff, and using that for a month or so. It's about right for me and the cycling I do. If I have understood the previous comments correctly (especially Brucey's), then for such low gearing, a Hebie Chainglider is not possible. Is that right?


From the Rohloff Manual pages 19-20 :

https://www.rohloff.de/fileadmin/user_u ... date_2.pdf

Sprocket ratios

The Rohloff SPEEDHUB 500/14 has a 526% range of gears, that means gear #14 is 5.26 times greater than gear #1. The 14 gears are evenly spaced out over this range in 13.6% increases. Through the choice of chainring and sprocket in use, the Rohloff SPEEDHUB 500/14 can be tuned for the specific riding purpose. The Rohloff SPEEDHUB 500/14 comes standard with a 16 tooth sprocket. 13, 15 and 17 tooth sprockets are available as alternatives.
In the following tables the distance travelled per crank revolution is listed for gears #1 and #14. The listed distance travelled per crank revolution is shown in the tables for a variety of sprocket ratios and wheel sizes (20", 26" and 28" wheels).
When the particular wheel/sprocket/chainring size and gear is not listed in the tables, then the following formula can be used to calculate the exact distance travelled per crank revolution of the Rohloff SPEEDHUB 500/14:
Formula key:
Distance travelled per crank revolution = W x C ̧ S x IGR
W = Wheel circumference
C = Chainring size
S = Sprocket size
IGR = Inner gear ratio listed in the following table
Inner gear ratio IGR = hub revolutions per sprocket revolutions of the Rohloff SPEEDHUB 500/14

gear #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
IGR
0.279
0.316
0.360
0.409
0.464
0.528
0.600
0.682
0.774
0.881
1.000
1.135
1.292
1.467


The tables or the following formula can be used to compare the Rohloff SPEEDHUB 500/14 to a derailleur gear system:
Ratio of the derailleur gear system = C ̧ S
Ratio of the Rohloff SPEEDHUB 500/14 = IGR x C ̧ S
Smallest permissible sprocket ratios (solo 100kg)
The sprocket ratio on the Rohloff SPEEDHUB 500/14 (e.g. 42:16) converts the slow rotational speed at the crank into a fast rotational speed at the sprocket and reduces the input torque for the Rohloff SPEEDHUB 500/14 in the same proportion. To prevent overstraining the hub, a minimum sprocket ratio of 1.90 must be used. With the available sprockets these minumum ratios are achieved by: 40:21, 36:19, 34:18, 32:17, 30:16, 28:15, 28:14, 26:13. This resembles a derailleur transmission of 22:40. Larger chainrings can be used without exceptions.


Page 20 and onwards gives comparison tables of gear ratios with derailleur geared bikes.

Sorry but the table above of gear ratios has come out vertically rather than horizontally.

HTH.

GrahamJ
Posts: 13
Joined: 18 Nov 2020, 8:15am

Re: What chainring and rear cog for Rohloff?

Postby GrahamJ » 20 Dec 2020, 3:50pm

Billy007 wrote:[...]
With the available sprockets these minumum ratios are achieved by: 40:21, 36:19, 34:18, 32:17, 30:16, 28:15, 28:14, 26:13. This resembles a derailleur transmission of 22:40. Larger chainrings can be used without exceptions.
HTH.


Thanks. My current bike, as bought, was a 3x9 MTB with 27.5" wheels and 2.25" tyres and a 17-110 gear inch range. It's currently 2x9 and 22-32T front, 11-40T rear, so a 15-80 range, with 22:40 as the lowest ratio. There's quite a few Rohloff options that are suitable, even with 29" wheels.