Got fed up having to refresh Sheldon Brown's site over and over and over again trying to work out all the information I needed to know for what my chosen Alfine gearing would give me…

So seeing as I had an hour spare, got busy on Excel and created myself an all singing, all dancing (well, not quite, but it does the job) spreadsheet for the Alfine, and now also the Rohloff Speedhub too.

Anyway, if you're interested, post your email address up on this thread and I'll email it to you for you to play with til your heart's content.

Hopefully it's fairly self explanatory, but it's totally unprotected so I should just mention that only input anything into the yellow boxes, and all measurements need to be in mm… That means 26" MTB rims are 559mm, 29ers and 700c are 622mm, tyre widths likewise in mm (so a 2" tyre is 51mm, a 2.2" is 56mm etc.), and also crank lengths…

Also the calculator works out what your equivalent gear would be if you had "normal" sized chainrings up front too… Say you wanted to know what your bottom gear is on your Alfine, but as an equivalent to if you had a "normal" 22T granny gear… Yup, it does that too…

So, just pop your email addy on here, I'll send it to you forthwith…

Feedback/comments/suggestions for improvement will all be gratefully appreciated too.

Hi that sounds interesting.

gordymackATbtinternet.com

Cheers
Gordymac

keppochATbreathe.com

Yes that sounds good.

keppoch

davenport_jamesAThotmailDOTcom

Cheers!

You guys have mail…

Anybody else, again just pop your email address down on this thread and I'll get back to you…

Yes please!
info"at"mcys.co.uk
Thanks.

Email it to me and I'll host it for you if you like meaning that you'll be able to provide a direct link to it and not have to email it.

Thanks

Very handy

Sounds interesting

ijs445raATtiscali.co.uk

Thanks

sounds like 'fun' 😉 could I use it to factor in Hammerschmidt ratios as well? I guess I'd just run it twice with the different equivalent front gears?

simon AT intrepidtravel DOT com

please

stw at northmalvern.co.uk

please
andyfb78ATgmailDOTcom

thanks!

mrcarlpeacheyAThotmailDOTcom

lovely.. good work
mister_chunkAThotmail.com

ade1963ATaol.com

that would be usefull

😀

garycartwrightAThotmail.com

You've all got mail

Clubber, have sent you mail about hosting it.

In the meantime, if anyone has any feedback at all, good, bad or indifferent, PLEASE let me know… I apologise, I'm sort of using you guys as beta testing guinea pigs I suppose, but once I know it's all 100% hunky dory then clubber can hopefully host it for me then it's there for the whole world to use!

Oh, and Stoner… You live in Malvern do you? I'm in Worcester mate… Must go for a ride sometime!

that's cool MaverickBoy 🙂 Really helps me see what I'm going to end up with when I finally get my Hammer + Alfine rig up and running (the gearing looks quite good according to your table, which is nice to know 🙂 )

I don't know if all your figures are correct but the speeds in the last column seem a bit low.

Very handy for looking at gearing comparisons and the effect of gearing changes – I know what the various conventional gearings with dérailleurs felt like so can see what he effect of altering chainring sizes is

Handy

tamarvin at googlemail.com

thanks!

psychle, be careful you don't strip the clutch on the Alfine running it with a Hammerschmidt… Someone on MTBR forum was running a 26T up front with a 22T out back, and killed his hub cos of too much torque! Let us know how it goes though…

TJ, I'm literally just off out for a few hours, but very keen to speak to you about your feedback. I thought the same as you when I looked at it, but I've double and triple checked my calculations for working out the speed. Might be I've got the calc wrong in the first place!

I don't know if all your figures are correct but the speeds in the last column seem a bit low

I kind of thought the same, but not sure how it's all worked out… 😳

The gearing calculations / ratios look fine. Its the road speed seems too low

I am running 32 / 18 gearing with the alfine. That comes up at the same as an 11/34 cassette with a 32 chainring which would seem right. I can hit the best part of 30 mph spinning like crazy in 32 /11 top gear. 25 mph for sure.

Now spinning like crazy – 90 cadence?? according to your calcs that only 20 mph. I don't have a cadence meter but I would have thought 90 seems about right. To reach 26 mph would be 120 cadence. could I be spinning that fast?

yes please…

bdsm72ATliveDOTcoDOTuk

ta 🙂

nah, spinning like crazy would be at least 100+ rpm surely? If you're really spinning out then 120 would be feasible?

How about uploading it to google docs as a public spreadsheet? Just an idea

80-90rpm is my normal road cadence. 120 will feel pretty fast. The fastest I've ever managed is 175rpm on my fixie at around 37mph on 48×18

175rpm 😯

Yeah but that's proper at the limit. In fact my back spasmed after that.

This is quite useful although it doesn't have the Alfine listed.

ashjATnetsoc.tcd.ie

Right, been out all night so sorry not got back to so many of you til now (hopefully you should all have emails by now)… Anyway…

To answer a couple of questions…

80-90rpm is not spinning like mad… That's a slow-normal cadence for me! 100rpm is getting more like it, 120rpm is quick… 175rpm on a fixie is ludicrous, but fair play I bet it gave you a rush! 😉

Anyway, have tested my calculations against the great Mr. Sheldon Brown's on his website… And there's a slight (like 1-1.5%) discrepancy on the speeds being chucked out… But it seems to go both ways depending on wheel and tyre size used, but it's never more than 1.5% different… So… I need to work out exactly how Sheldon Brown has calculated the total circumference of a bike wheel, cos it's obviously different to the way I assumed to (wheel diameter in mm, 559 for 26", 622 for 29er, + tyre height/width x2, all xPI, to give total circumference)… So if anyone can shed any light on this, especially regarding rim diameters (seems it's not so obvious as I first thought), then let me know!

Off to do a bit more research on it now… But it answer to all the worrying about cadence seeming way too high for intended MPH… You're wrong, your cadence is that high… To get within 1-1.5% of the MPH my calculator is chucking out anyway… 😉 My only other thought is that perhaps his site does quite a bit of rounding up/down in a calculation before you get the final answer (which is only to 1 decimal place anyway), whereas mine is going to the Nth decimal place in the calcs, only does it round up/down to 2DP in the answer column… Who knows!

FWIW the rest of the calculations come out spot on with those generated on Sheldon's site…

avdave2 will take a look at that when I get onto my PC (it's a .exe file, I'm on my Mac at the mo) and take a look… If it's any good, I'll probably get in touch with him…

Interesting.

Ok – so "spinning like a mad thing" is 120+ cadence?

Interesting.

Ok – so "spinning like a mad thing" is 120+ cadence?

Indeed

What did you think you pedalled at normally if you thought 80-90rpm was quick? I used to mash big gears when I was a kid, before I learnt that I was much better off sitting and spinning more, and even then would've considered 60rpm very slow… Think about it, measure a second, and measure yourself turning the pedals on a bike one full turn whilst taking a whole second to do so… It's VERY slow!

Got any ideas about wheel size/diameters? ie. where the 559 for 26" wheels, and 622 for 29ers and 700c is taken? I thought it was on the outside edge you see… Maybe that's where I'm making a mistake?

EUREKA! I've worked it out…

Sheldon was taking his tyre size diameters from the table at the bottom of the following link…

http://sheldonbrown.com/gain.html

They are an approximation, not totally accurate (mind you, is any bike tyre in its size!), and therefore his calculator has some margin for error built in… Which makes mine totally more accurate!!! 😀

I knew I wasn't crazy… 😉

BED TIME now though… 😳

Right, now up to v3 of the calculator…

A few minor things refined, all measurements now in mm not inches (so I don't confuse myself!), and tabs for SRAM I-Motion 9 and Sturmey Archer 8 speed hubs now added in addition to the Alfine and Rohloff tabs…

Will email it to everyone in a bit… And possibly ask Clubber to host this one pending a touch more testing…

if you don't mind me adding it to the Genesis site, enquiries@genesisbikes.co.uk – thanks. We get asked about ratios a fair bit and i'll credit you for the table if you don't mind me sending it on.

cheers
James

alexredwoodAThotmailDOTcom

Would be greatly appreciated…..

Cheers,

Alex

yes please 🙂 damitamit@gmail.com

Can you send it to me please benny_boy35 at hotmail.com