# Rolhoff Belt drive on a 29er+ help please



## Johnclimber (Jan 9, 2008)

I'm looking at a new 29er+ frame that is belt drive compatible and I would like those who run Rolhoff belt drive's help please.

I'd like to get near the gear range of my standard 29er - 3 x 9 (44 - 32 - 22 front & 32 x 11 rear), now I know this isn't possible high end but I could do with the spinny gears lowdown for climbing.

The front will fit a 46 tooth/pulley Gates cog (no larger), how close will a 19 tooth/pulley on the back give me to what I'm after?

What difference a 20 or 22 tooth/pulley make the gear range?

Please keep your answers simple for an idiot like me to understand...

Thanks and Happy Christmas to you all :thumbsup:


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## ladljon (Nov 30, 2011)

Check out Cycle Monkey....They have the answers....I'm running Rohloff chain....38t-16t and is the same as conventional 3X9 drivetrain...also check out the Rohloff or Sheldon Browns site for gear ratios....A 46x16 would be the same as a 24x30..for climbing. So an 18, 20, or 22t would climb a tree....


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## Johnclimber (Jan 9, 2008)

Cheers Ladljon, but I don't think the Gates belt pulley's are the same spacings as chain teeth spacing.

Does anyone know how different the pulley to tooth ratio is.

Anyone using a Gates Belt over a chain out there with the answer?

Cheers


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## anga (Aug 22, 2011)

What matters is the tooth ratio and not the spacing.
Use a spreadsheet.
Start with the gear ratios of your 3 x 9 setup and sort them.
Get the 14 gear ratios of the Rohloff hub.
Use a multiplier (call this A) to scale the Rohloff ratios to get as close as possible to the 3 x 9 gears. 
A = teeth in front pulley/teeth rear sprocket
The number of teeth in the rear sprocket is 46/A.


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## ladljon (Nov 30, 2011)

U really have to go by the size chainring will fit UR frame....

conventional 46/12 =rohloff 40/15=belt 50/19

conventional 22/34=rohloff 38/16=belt 46/19

conventional 24/32=rohloff 36/13=belt 55/20-60/22

I would say 46/19

Gates carbon Rohloff drive manual

Front chainring 104 mm for MTB


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## Johnclimber (Jan 9, 2008)

ladljon said:


> U really have to go by the size chainring will fit UR frame....
> 
> conventional 46/12 =rohloff 40/15=belt 50/19
> 
> ...


I don't understand a word of the above 

But I do understand and feel relieved about the following :thumbsup:



ladljon said:


> I would say 46/19


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## ladljon (Nov 30, 2011)

A 46/19 would give U the same low climbing ratio of a 22/34 conventional gearing....


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## Saul Lumikko (Oct 23, 2012)

Belt drive gear ratios are calculated the same as with chains. The different pitch doesn't matter, because it's different by a same amount through the system. 

For example 46/19 with a belt drive has the same gear ratio as 46/19 with conventional chain drive.


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## Johnclimber (Jan 9, 2008)

Thanks to you all for helping out a maths idiot like me.

I really liked the comment above "22t would climb a tree"

I'll post up pictures of the build at the end of Jan when it's here and I'll let you know my luddite thoughts as well.

Happy New Year


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## fokof (Apr 24, 2006)

Important thing is to stay in the length of the chain stay

The Gates application for iPhone works really well to find the right combo.


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## CycleMonkey (Nov 20, 2013)

Johnclimber said:


> I'm looking at a new 29er+ frame that is belt drive compatible and I would like those who run Rolhoff belt drive's help please.
> 
> I'd like to get near the gear range of my standard 29er - 3 x 9 (44 - 32 - 22 front & 32 x 11 rear), now I know this isn't possible high end but I could do with the spinny gears lowdown for climbing.
> 
> ...


Sounds like a fun project!

Most of our customers are okay running a 46/20 ratio on standard 29ers, but most of our 29+ customers have preferred the lower 42/20 setup.

We built both up of the bikes below with a 46/20 ratio at first, but the customers eventually decided to switch to 42/20.

The Monkey Lab: Twenty2 Cycles Belt Drive Rohloff 29+








The Monkey Lab: Surly Krampus with a Rohloff and belt drive








Let us know if you have any other questions.


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## Johnclimber (Jan 9, 2008)

CycleMonkey said:


> Most of our customers are okay running a 46/20 ratio on standard 29ers, but most of our 29+ customers have preferred the lower 42/20 setup.
> 
> We built both up of the bikes below with a 46/20 ratio at first, but the customers eventually decided to switch to 42/20.
> 
> Let us know if you have any other questions.


I think for the UK the 42/20 might be too spinny, where about's are your customers with this gear ratio? Hills or Mountains?

I'm planning on 46/19 which will be a touch harder but give me a bigger top end.


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## CycleMonkey (Nov 20, 2013)

Johnclimber said:


> I think for the UK the 42/20 might be too spinny, where about's are your customers with this gear ratio? Hills or Mountains?
> 
> I'm planning on 46/19 which will be a touch harder but give me a bigger top end.


Those 42/20 setups have been used for a variety of terrain, including customers here in the SF Bay Area and in the Canadian Rockies.

Keep in mind the 29+ tire makes for 30.5 diameter wheels.

46/19 should be okay if you expect to ride a lot of flatter terrain or if you are a stronger rider.


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## Johnclimber (Jan 9, 2008)

Thanks for your help CycleMonkey

I'm going for a 42/20 set up, with a 2nd belt and a 46 front to run 46/20 on flatter local rides.

I'll post up pictures and reviews once it's here in April


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## CycleMonkey (Nov 20, 2013)

Johnclimber said:


> Thanks for your help CycleMonkey
> 
> I'm going for a 42/20 set up, with a 2nd belt and a 46 front to run 46/20 on flatter local rides.
> 
> I'll post up pictures and reviews once it's here in April


Sounds good. Definitely post pictures here; we'd love to see it!


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## Johnclimber (Jan 9, 2008)

Cheers for your help, it's going on a Travers Rudy Fat










Rudy Fat 29+ Frame - Travers Bikes.com

Travers Bikes ? Rudy Fat ? New UK Titanium 29+ | FAT-BIKE.COM


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## Schmucker (Aug 23, 2007)

I'm running 42/20 on my belt drive Rohloff 29+.


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## Johnclimber (Jan 9, 2008)

Schmucker said:


> I'm running 42/20 on my belt drive Rohloff 29+.


Do you ride it in the hill's, are the hills big/steep/rough etc, etc?

How would it compare to a 29er 3 x 9 gearing on the lowest gears when going up hill please?


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## mangoman (Oct 25, 2005)

@Johnclimber: I also wanted a 29er+ with Rohloff + belt drive. I know Rohloff, but I don't know jack about belt drive. So I'm trusting Cycle Monkey to do my new build—completely. Neil and Co. are setting up a Surly ECR for me now, and I was willing to sell the current Precious (my Fatback) to fund this new monster All-Do bicycle.

Whatever that's worth.


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## rkt88edmo (Mar 28, 2004)

mangoman said:


> @Johnclimber: I also wanted a 29er+ with Rohloff + belt drive. I know Rohloff, but I don't know jack about belt drive. So I'm trusting Cycle Monkey to do my new build-completely. Neil and Co. are setting up a Surly ECR for me now, and I was willing to sell the current Precious (my Fatback) to fund this new monster All-Do bicycle.
> 
> Whatever that's worth.


Can't wait to se the ECR, sounds like exactly what I'd want for a next rig.


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## mangoman (Oct 25, 2005)

rkt88edmo said:


> Can't wait to se the ECR, sounds like exactly what I'd want for a next rig.


_*You*_ can't wait? Dude...

Neil (from Cyclemonkey) has no idea that I've been sleeping in his closet every night, holding my parts list and my little Cyclemonkey doll, softly sobbing myself to sleep...

*(Wow, that was really creeptastic.)*


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## CycleMonkey (Nov 20, 2013)

mangoman said:


> _*You*_ can't wait? Dude...
> 
> Neil (from Cyclemonkey) has no idea that I've been sleeping in his closet every night, holding my parts list and my little Cyclemonkey doll, softly sobbing myself to sleep...
> 
> *(Wow, that was really creeptastic.)*


I know now. I'm checking my closet from now on before I go to bed. 

-Neil


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## mangoman (Oct 25, 2005)

CycleMonkey said:


> I know now. I'm checking my closet from now on before I go to bed.
> 
> -Neil


Busted.


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## Johnclimber (Jan 9, 2008)

rkt88edmo said:


> Can't wait to se the ECR, sounds like exactly what I'd want for a next rig.


After riding the Krampus I really wanted the ECR but the lack of mud clearance over here in the UK was it's problem, plus it's heavier than what I've ordered.

I've gone for the new Ti Angus 29er+ from Travers Bikes, it's so new it's not even on the website as yet, but designed for belt drive/SS.
Travers Bikes.com - Home

ETA late March/April


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## Johnclimber (Jan 9, 2008)

The Rohloff's turned up with the Halo front hub and matching rim strips.

The cog will go when the CDX bits arrive from Gates.










4 weeks to wait


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## mangoman (Oct 25, 2005)

Nice. That's gonna be a beastly beauty. 

My ECR is finally enroute. Due next week. Pure murdered-out darkness, although that red Rolly was definitely tempting.


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## Johnclimber (Jan 9, 2008)

Johnclimber said:


> The Rohloff's turned up with the Halo front hub and matching rim strips.
> 
> The cog will go when the CDX bits arrive from Gates.
> 
> ...


And today my 42 x 20 turned up (thanks on here for the guidance)



















Just the Ti frame to wait for now


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## mangoman (Oct 25, 2005)

Nice pics! When's your frame due?


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## Johnclimber (Jan 9, 2008)

mangoman said:


> Nice pics! When's your frame due?


Around 4 weeks away


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## intheways (Apr 19, 2004)

That's gonna be a sick bike. I have a rohloff disc hub cap and I just need a hub to put it on.


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## mangoman (Oct 25, 2005)

Diggin' this Rolly + belt drive combo on my new ECR:


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## anga (Aug 22, 2011)

^ I like the clean and elegant look of this build.
Enjoy!!


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## mangoman (Oct 25, 2005)

anga said:


> ^ I like the clean and elegant look of this build.
> Enjoy!!


Thanks. Enjoying it very much, and getting it dirty this weekend.


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## anga (Aug 22, 2011)

Can you post closeup photos showing where the frame is split for the belt-drive and how the torque arm/OEM/OEM 2 plate is fitted on the NDS?


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## mangoman (Oct 25, 2005)

anga said:


> Can you post closeup photos showing where the frame is split for the belt-drive and how the torque arm/OEM/OEM 2 plate is fitted on the NDS?


Here's the frame split. Don't have one of the NDS Rohloff plate yet, but will try to capture one yet this weekend.


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## anga (Aug 22, 2011)

Thanks--I don't think the split seat-stay came with the frame.


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## manensky (Aug 22, 2011)

anga said:


> Thanks--I don't think the split seat-stay came with the frame.


Yep, split seat-stay doesn't come as a default with ECR frame.

Anyway, here is NDS photo of my hoffed ECR:








To utilize ECR's Rohloff-specific feature, you will have to have this axle plate (TS OEM2):


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## anga (Aug 22, 2011)

Thanks--looks like you've a belt drive.
Can you point out where the OEM2 plate is attached to the dropout?


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## manensky (Aug 22, 2011)

anga said:


> Thanks--looks like you've a belt drive.
> Can you point out where the OEM2 plate is attached to the dropout?


My ECR + Rohloff combo is with a chain since belt would not be a robust solution on my use (rock rubbing , tree branches between belt&beltring&etc) 

I hope that this pic will show, how OEM 2 plate is attached to the frame:








So from the previous NDS pic, OEM 2 plate's mouth is biting that lowest bolt under brake caliber bolts.


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## Yoreskillz (Feb 10, 2011)

That's a beaut Mangoman!!! I bobbled back and forth from the ECR and the 14' Salsa Fargo, in the end the Fargo won out. Cycle Monkey is building the wheels for it now, and I am seriously considering having a splitter installed to try out the belt drive....

Eager to hear how it goes for you all!


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## mangoman (Oct 25, 2005)

Yoreskillz said:


> That's a beaut Mangoman!!! I bobbled back and forth from the ECR and the 14' Salsa Fargo, in the end the Fargo won out. Cycle Monkey is building the wheels for it now, and I am seriously considering having a splitter installed to try out the belt drive....
> 
> Eager to hear how it goes for you all!


Thanks! Riding around the beach and back bay areas yesterday, it was nice to not have sand stuck to chain lube. Definitely glad I did the belt and encourage you to go for it.


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## intheways (Apr 19, 2004)

Yoreskillz said:


> That's a beaut Mangoman!!! I bobbled back and forth from the ECR and the 14' Salsa Fargo, in the end the Fargo won out. Cycle Monkey is building the wheels for it now, and I am seriously considering having a splitter installed to try out the belt drive....
> 
> Eager to hear how it goes for you all!


I've been thinking about this same setup. Curious to hear how you like it?


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## mangoman (Oct 25, 2005)

intheways said:


> I've been thinking about this same setup. Curious to hear how you like it?


The Fargo or the ECR?


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## intheways (Apr 19, 2004)

mangoman said:


> The Fargo or the ECR?


My bad. I meant to include the quote. I was referring to the Fargo, though I would imagine the ECR is awesome, too


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## monogod (Feb 10, 2006)

mangoman said:


> Here's the frame split.


nice. who did it?


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## mangoman (Oct 25, 2005)

monogod said:


> nice. who did it?


I think Retrotec/Inglis does the frame split work for CycleMonkey.


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