jcwitte

After visiting Sheldon brown's gear calculator, it seems the overall advanatage to lowering the gearing would be negligible. I have a Trek 520 with the 50/42/30 and 11-32 rear. The three lowest combinations in gear inches that I'd get is 33.8, 28.9, and 25.3. I have seen some people say they change to a 26 granny. If I did this, my bottom three combinations in gear inches would be 29.2, 25.1, and 21.9.

So, really I would only be getting one more combination that is of any significance. With a 24 granny, you get two lower combinations of any significance (24.8, 21.2, and 18.6). How many times have you all actually needed your bottom combination to the point that you would have had to get off your bike and walk? Or am I missing something else about the whole gear inch thing?

edtrek

This page about my Trek 1100 contains the charts and details,
but here's what my front rings / rear cassette and lowest gear-inches were:

OEM: front 30-42-52 / rear cassette 12-28 / 29" granny
2004: front 30-42-52 / rear cassette 13-34 / 24" granny
2005: front 24-42-52 / rear cassette 13-34 / 19" granny

So I went from a OEM granny gear of 29 inches to a post-mod granny gear of 19 inches.
And I'm loving it! One of the best upgrades I've every done, and not that expensive!

chipcom 

You will appreciate that 21.9 gear inch granny when doing a long climb with a full load. You might even want to consider the 24 to get you closer to 20 gear inches on the low end. I'd much rather spin, at even 40rpm, than walk - at 20 gear inches you are still moving faster than you would be walking a loaded bike uphill.

roadfix

When you're carrying a heavy load it sure makes a difference. I would rather winch my 65 lb bike up a long steep climb pushing 18 inches at 2 mph than walk it...

Bekologist

I drop it into the lowest of my low (26 front 34 rear) on my loaded touring bike up most every long climb.

it's nice to keep it in 2nd though, and keep extreme low as a resting gear even during fierce, multi hour climbs....drop into crawling granny, grab some drinks and snacks on the fly, relax for a couple of minutes, then pop back up into 2nd to continue the grind.

supcom

How low a gear do you need? That's up to you. I've used the lowest gear on my hardtail MTB while towing a trailer and still had to take breaks on the way up (15% paved grade). It just depends on what mountain you're climbing, how much load, and how strong you are.

Oh, and sometimes the wind decides to blow in your face up that mountain, just to make it more fun.

jcwitte

The main reason I am second guessing this is that I tried switching out to a 26 granny and it did not work. When I put the 26T ring on, I couldn't get into the smaller five or six rings on the rear cog (9 spd) without the chain rubbing against the ramps on the middle chainring. Pretty frustrating. So It appears that I would have to switch out the entire crank and BB at a cost of at least $160.00. So I looked up what the benefit would be and realized it is just one lower gear combo. I realize that there may be times when I would appreciate the lower gear, but I'm just curious as to how many times you guys have actually used that lowest possible gear that I would have to pay about $160.00 to get. If there was just like one or two stretches in your entire tour that you needed that lowest gear, then I'm thinking it may not be worth $160.00 to me. It's just hard to judge I guess since there aren't any significant hills or mountain-like climbs in central Illinois.

jcwitte

Well, I guess I'll have to go find the biggest hills around here (not too many exist around here) and test it out with a full load. I suppose that really is the best way to answer my question. I rarely even use the 30 for my regular commuting. I'll do that tomorrow.

Bekologist

ride 70 miles fully loaded first, then up and down the hill about 20 times, maybe?

Whatever gearing you go with, I'd recommend trying the approach of 'second gear' as the rolling granny, and 'extreme low' as the resting granny.

bkrownd

There is a practical limit to your granny gear. There is a point where either you won't be able to go fast enough to maintain balance, or if struggling against a load/slope your front tire will lift off the ground so much you won't be able to maintain steering or balance. The two lowest gear combos on my mountain bike are pretty much useless because of this.

NoReg

"front tire will lift off the ground so much you won't be able to maintain steering or balance"

Put 30 pounds on your front wheel, should be fine.

jcwitte, what I find to be the case is that if I'm loaded touring I rarely use the big chain ring, and if I'm riding around town I rarely use the small one. Makes me feel maybe the 10 speed (12 or 14) isn't such a bad design afterall.

Going east in Quebec last year I hit a headwind so bad that with my not inconsiderable bulk balanced over the pedal in my lowest gear on my 23 speed, mid 20s, the bike would not move forward! Road signs were twisting back and forth. This was not a gust, but some sustained wind rain coming through a potatoes marsh. Miller time! I find it isn't so much the hills that get me as the wind. Around here one rarely finds a hill that lasts several days.

chipcom 

If you are only going to be touring in your area, you may be fine, but if you plan on long distance touring the lower gearing would be wise.

bkrownd

...if that's an option, yes.

wagathon

Don't know if you need them, but it is amazing how low a gear you can get by just swapping out the road triple for a MTB triple, e.g., 22/32/44 or 26/36/48, while using just a 12-27 freewheel. The narrower cluster (instead of to 32T), gives you a lot more closely spaced gears without a lot of double shifting (however, you do give up the really high gears).

22F / 27R for example is just 0.81 revolutions of the rear wheel (i.e., about 21.9"--same as for your 26F / 32R option) compared to nearly one-to-one with the 30 /32 combination.

MichaelW

In tried lowering the granny ring oon my Campy triple but it never realkly worked well. I swapped the chainset for an LX and lowered the Campy front mech and it is much better.
The low gear really helps me on a mountain trail or an 18% grade.

dreamy

Make sure you ride 100 miles first!

pur1138

I envy people that don't live in hill country. I built my LHT with a 22-34 low gear and use it regularly. The bike with racks, dynohub etc. weighs 36 lbs. Empty.
Loaded it's over 100.
I use that granny a lot. I also push a lot, but watching the speedo at 2.5-3mph pushing and 4mph pedaling gives a lot of incentive to pedal.
The frame flexes a lot when that heavily loaded at those low speeds and is really a handful, but at least it's doable.
Good upper body workout too.

Kevin

Cyclist0094

in a cold pouring rain...

wagathon

Ride with a teenager--who just gets stronger everyday--and learn after about day 3 that he has been staying with you the whole time on a Walmart MTB with the rear brakes dragging.

nun

You might want to check the chain line, but using the small rear cogs with the 24t granny should be avoided anyway as your chainline will be far from optimum and you'll have the same ratios in the middle ring anyway.
For me there are 3 basic gear choses, leaving out the old half step plus granny and sigle speed

53-39 with 11-25 - for young racers or old supermen
48-36-24 with 11-34 - for touring riders who really must have something just above 100 gear inches to save face among racers (44-34-22 with 11-27 is similar for those who don't like old school 110/74 compact cranks)
40-24 with 11-34 - old touring and recreational riders who are no longer vain enough to need 100 gear inches.

Or you could just go the Rohloff hub route

Wil Davis

$160?

I recently changed my Veloce 52/42/30 for a Veloce 53/39 which included BB set (which I didn't need) for $51 on eBay. I also looked around the InterNet and found a Shimano Exage LX-500 50/40/32 for my MTB (swapped out a 46/36/24) for $39. I went with the higher gears on the MTB as I use it mostly on the road, and wasn't using the lower gears - same for the Bianchi road-bike. Look around on the net - you'll be surprised what you can find…

- Wil

jcwitte

I'm probably not describing all of this very good, but here goes.....

When I tried the 26T, I could not shift onto the smallest 5 or 6 rings on the rear cog without the chain rubbing on the 42's shifting ramps. The actual ring I bought is a generic one from Nashbar. The chainring was flat. The 30 that it replaced had a ridge near the outer edge of the ring allowing the teeth to be further away from the 42 chainring. In other words, the actual teeth sat on a sort of ridge that acted as a spacer. I'm guessing that if I could find a 26T chainring that had a similar ridge, then my problem would be solved. Does anyone know where I can get one like that? Are the TA rings sold by Peterwhite cycles like that? https://www.peterwhitecycles.com/chainrings.asp

I'll try to illustrate what I mean by flat versus a rdige....

(30T chainring with a ridge near the teeth) Note the extra spacing between the teeth of the 30 and 42
52__________
42________
30-----__



(flat 26T chainring)
52__________
42_______
26-----

I need to go for now (go Bears) but I'll check back later for any replies and try to answer any questions to clarify any of this.

Bekologist

Hi JC witte,

you might just try spacers on that 24 ring...wait, before you try that....

I've got a 520 with the same stock rings like yours, and also my heavy touring bike that is actually running a 24-36-46 with 11x34 in the back.

Before xmas I jotted down some gear inch ratios from Sheldon's GREAT gear calculator so I could pour over them on the airplane, and here were my (possibly incorrect) inferences...

****MAJOR EDIT BELOW**** had to substitute 'lowest' cogs for 'smallest', doh! brain freeze


on the 520 with stock gearing, you only have to run the lowest three rear cogs with your small chainring before you duplicate gear travel in 4thcog/small ring & your lowest cog/middle ring.

So, on stock, only the first lowest three on the front small ring, then bring it up to middle ring. Then you can do some fancy cross ring shifting if you want to keep the steps small.

On my bike with 24-36-46 and 11-34 in the back, I only need to run the lowest three again, until I get a gear near-duplication in lowest cog/middle ring - so again, the same scenario, I only HAVE to use the the lowest three cogs in my smallest chainring, then can move up into the middle ring.

There's a lot of fancy cross shifting you can do and alternate chainrings to step small, but I'm a straight shifter myself. My brain doesn't do math while riding very well. I think i probably get away with using the lowest 5 or so cogs before I remember to shift into the middle ring on either the 520 or my heavy tourer.

Hope this helps...

michaelnel

I had a 24/36/46 with 11/34 8 speed on my Atlantis. I used the granny a LOT on that bike (90# fully loaded), but with 26/36/46 on my Soma Doublecross commuter / allrounder I almost never use the granny. For loaded touring it sure comes in handy though!

dreamy

I know what you mean – I had the same issue when replacing the 30 with a flat 26 on my Fuji, and had to shell out $10 for one that was offset.

Having said that, I would not do another long tour involving mountains with this setup. The jump between 26 and 42 is too big – not only in ratio but also when shifting down the chain kept wanting to jump off onto the BB unless careful and shifting up I had to overshift (I had sti shifters though). I would replace the whole crank with 48-36-26.

Around home unloaded I never use the 26, even on steep hills, but would not tour without it...