# Gear inches...what is usable?



## OldschoolReloaded (Nov 20, 2012)

I am thinking of building up an Surly ECR for bike camping / touring and since I am a fan of the IGH I have settled on a Rohloff. I am in good shape but want a big range in order to help with steep hills. I was even thinking of adding a Schlumpf Speed drive which will get 868% gear range. However, you mostly see these on recumbent trikes as they have no need to balance at slow speed. So although you can now gear things down to the point of being like a trucker shifting through gears with a great range, at what point does it become useless for a DF bicycle. You can only ride so slow...right?


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## verslowrdr (Mar 22, 2004)

I haven't met a low gear ratio yet that I couldn't use, and the right one seems to be a bit lower than the lowest I've currently got, lol.... I'm currently running a granny of 22x36 on 26" wheels and it's awesome.


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## ECR (Sep 25, 2013)

Gain Ratios--A New Way to Designate Bicycle Gears
"The lowest gear on most mountain bikes is around 22-26 inches."

If you were to setup with Rolloff 14-speed IGH and 34t chainring similar to Logan on his tour of Africa then your gear-inches would range from 17.7-93.2.
Surly ECR: Bike Touring 1,000 KM Impressions - Pedaling Nowhere

Rohloff 14-spd w/ 29x3 tire & 16t cog
chainrings: 34t
gearinches: 17.7-93.2
[email protected]: 3.2-16.6
[email protected]: 4.7-25.0

My ECR is setup with Alfine 11-speed IGH and 26/39 chainrings which come standard on Surly OD crankset. I have never wanted smaller gearing, have rarely used lowest gear and find it difficult to balance at this low gearing.

Alfine 11-spd w/ 29x3 tire & 18t cog
chainrings: 26/39 (73mm OD std)
gearinches: 22.8-139.5
[email protected]: 4.1-24.9
[email protected]: 6.1-37.3

Sheldon Brown's Bicycle Gear Calculator


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## vikb (Sep 7, 2008)

OldschoolReloaded said:


> You can only ride so slow...right?


Yes. At some point you are hamster pedalling and going nowhere.



> The Schlumpf Mountain Drive is the best choice when you are looking for the lowest possible gear ratio. The wide 2.5 reduction ratio can offer an effective chainring size that is lower than any available chainring (depending on physical chainring selection). It also has the highest running efficiency of Schlumpf's offerings, making it the best choice for HPV's or other land-speed vehicles.* It is not recommended for use with the Rohloff SPEEDHUB 500/14 due to conflicts with Rohloff's minimum gear ratio requirement.*


Schlumpf Innovations Gearing Systems - Speed Drive, Mountain Drive, High Speed Drive

Note that you can't use a Schlumpf Mountain Drive [low range version] with a Rohloff and maintain your warranty.

Now if you are a low power rider you can ignore the warranty legal low input gearing restriction, but you'll have to decide how low you want to go before you risk shearing the torque limiting pins in the Rohloff. They can be replaced, but you'll have to ship the hub for service.

It's cheaper and safer to start with the lowest legal input ratio and work your way down by swapping in smaller chainrings. Just get a splined BB/crank so that you aren't limited by the BCD of the crank.

I'm running 34 x 16T on a Krampus with lightweight gear for dirt road and singletrack touring. I could probably use a 32 x 16T on occasion, but 30 x 16T would be so low I'd never get to the bottom of the Rohloff's gear range.

I'll just walk if it's faster than pedalling.


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## watts888 (Oct 2, 2012)

When I put my 26" in a 22T-32T gear, i have a hard time keeping balance unless I'm spinning like crazy. If my bike was loaded down, it'd be even worse. If my speed is anything lower than 2.5mph according to sheldon browns gear calculator, its useless for me.


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## bsieb (Aug 23, 2003)

I find my bike is more stable with my bikepacking load, especially when riding off trail. I don't have an especially low gear, 34/20 with an Alfine 8 IGH 29er, but I don't mind a push break now and then either. Spinning madly on flats seems undignified, maybe slightly less so on clipless, but on the whole not as impressive as simply standing and delivering.


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## She&I (Jan 4, 2010)

watts888 said:


> If my speed is anything lower than 2.5mph according to sheldon browns gear calculator, its useless for me.


What he wrote.


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