My gearing is too high

lil.godzilla · February 2021

I have a 2012 Giant Defy 2 with the Tiagra groupset, but the chain, cassette, and chainrings are due for replacement. Currently it has the stock 34-50 chainrings and 11-25 cassette.

I don't really ride hills, most of my riding is commuting so I can't always ride fast with the heavy traffic and parked cars. It also gets very windy where I live (NZ).

I find I almost never use the 3 smallest sprockets on the cassette and would like to get smaller chainrings if possible. I've been playing around with gearing calculators and I think I would like a 44-46t big chainring, and then a 11-25 or 11-28 cassette.

I've attached pics if it helps. And I need to replace my shifter cables!

I would also like a crank arm power meter. Is there any way I could do all this? I sort of feel like I have a 7 speed cassette sometimes not being able to use all the gears.

MattFalle · February 2021

Just buy whatever chainrings you want and fit them. Loads available on the internet.

Fit whatever cassette you want. Loads available on the internet.

Fit a new chain to match the new chainringss, adjust mechs suitably, fit new inner and outer cables.

Re powermeter, I wouldn't bother until you can pull the gearing.

webboo · February 2021

As above. If you need smaller gears that you have, a power meter will just tell you haven’t got any.

lil.godzilla · February 2021

So will any 46T chainring with the correct 110 BCD that is designed for a 10S drivetrain fit? Will I have to replace any other components or is the new chainring simply bolt on to what I already have?

My front derailleur bolts onto the frame rather than a clamp style, can I drop it down lower somehow even though it already appears to be adjusted quite low down on the mount already? Like an extender or something?

aberdeen_lune · February 2021

I don’t think you will be able to set the front mech properly on a 46t chainring if you don’t have any adjustment left to drop it lower.

Suggest you just change the cassette for an 12-28, replace the chain and cables both inners and outers.

For a power meter I suggest Fevero Assiomo pedals. They are brilliant, very reliable.

You will still have overlapping gears but you won’t have the 11 tooth.

MattFalle · February 2021

lil.godzilla said:
So will any 46T chainring with the correct 110 BCD that is designed for a 10S drivetrain fit? Will I have to replace any other components or is the new chainring simply bolt on to what I already have?

My front derailleur bolts onto the frame rather than a clamp style, can I drop it down lower somehow even though it already appears to be adjusted quite low down on the mount already? Like an extender or something?

can you post a piccie of your mech please?

the other alternative if you can't go any lower is to go 1x - ie only one chainring at the front.

MattFalle · February 2021

Ah - just double looked on your piccie above.

seems that you may not be able to drop the mech far enough - but difficult to say - so 1x or a mahoosif cassette and long cage rear mech.

tbh, 1x will be easier, cheaper.

junglist_matty · February 2021

lil.godzilla said:
I find I almost never use the 3 smallest sprockets on the cassette

Most average cyclists don't use them either, they're mostly there for tail-winds, downhills, sprints/intervals etc...

Based on the average cadence of an average road cyclist (which is approximately 70rpm) and assuming you've got a 25mm tyre, when in the big ring (50T) your speed in the lower sprockets would be:

11T = 25mph
12T = 23mph
13T = 21.2mph
14T = 19.7mph
15T = 18.4mph

If you've got gears in the middle of the cassette that work for you, then what's the issue here? Most of my time is spent in the big ring (52T) and the mid-cassette range (my average cadence hovers around 80-90rpm, or higher on hard rides).

simon_e · February 2021

I doubt you'd have a problem fitting a 46T front chainring. I'm thinking of doing this myself when my Trek's 50T ring wears out.

If you don't need winching gears have you considered trying a 1x setup? I've done this on the commuter. I like the simplicity and no more chopping between front rings like on the compact (I used to have a triple and used the middle 39T for at least 95% of my rides).

42T with 12-30 gives a range of 37-92" while 11-28 provides 40-100". A 46x12 top gear is 101", the same as 50x13. That's quite a big gear.

11-28, 12-28 and 12-30 tooth 10-speed cassettes are below. Personally I'd go 12-up and sacrifice the 11t to get the more useful 14t.

11 12 13    15    17    19   21    24     28
   12 13 14 15    17    19   21  23  25   28
   12 13 14 15    17    19   21    24   27   30

lil.godzilla · February 2021

aberdeen_lune said:
I don’t think you will be able to set the front mech properly on a 46t chainring if you don’t have any adjustment left to drop it lower.

Suggest you just change the cassette for an 12-28, replace the chain and cables both inners and outers.

For a power meter I suggest Fevero Assiomo pedals. They are brilliant, very reliable.

You will still have overlapping gears but you won’t have the 11 tooth.

Is there any kind of part I can get that can drop my existing front derailleur lower, like a different bracket or something?

Otherwise the 12-28 idea sounds good.

MattFalle said:
Ah - just double looked on your piccie above.

seems that you may not be able to drop the mech far enough - but difficult to say - so 1x or a mahoosif cassette and long cage rear mech.

tbh, 1x will be easier, cheaper.

The only thing I don't like about a 1x is the potential for having wider spacing between the gears. I like fairly narrow spacing. Unless the chainring is quite small which would make up for that I guess...

I could put in a medium or long cage 105 derailleur...

junglist_matty said:

lil.godzilla said:
I find I almost never use the 3 smallest sprockets on the cassette
Most average cyclists don't use them either, they're mostly there for tail-winds, downhills, sprints/intervals etc...

Based on the average cadence of an average road cyclist (which is approximately 70rpm) and assuming you've got a 25mm tyre, when in the big ring (50T) your speed in the lower sprockets would be:

11T = 25mph
12T = 23mph
13T = 21.2mph
14T = 19.7mph
15T = 18.4mph

If you've got gears in the middle of the cassette that work for you, then what's the issue here? Most of my time is spent in the big ring (52T) and the mid-cassette range (my average cadence hovers around 80-90rpm, or higher on hard rides).

I do have gears in the middle of the cassette that I like and use, but I would prefer to be able to use more of the cassette with narrower spacing between the gears with a smaller chainring. If I have a 46t instead of a 50t chainring that means I could use 1 sprocket smaller maybe on the cassette.

simon_e said:
I doubt you'd have a problem fitting a 46T front chainring. I'm thinking of doing this myself when my Trek's 50T ring wears out.

If you don't need winching gears have you considered trying a 1x setup? I've done this on the commuter. I like the simplicity and no more chopping between front rings like on the compact (I used to have a triple and used the middle 39T for at least 95% of my rides).

42T with 12-30 gives a range of 37-92" while 11-28 provides 40-100". A 46x12 top gear is 101", the same as 50x13. That's quite a big gear.

11-28, 12-28 and 12-30 tooth 10-speed cassettes are below. Personally I'd go 12-up and sacrifice the 11t to get the more useful 14t.
11 12 13    15    17    19   21    24     28
   12 13 14 15    17    19   21  23  25   28
   12 13 14 15    17    19   21    24   27   30

That does seem to make some good sense...

piker2 · February 2021

If changing from a 50T to a 46T will allow you to use a smaller sprocket will it not also make a bigger sprocket redundant. IMHO simply changing chainrings will not be of any benefit to you.

focuszing723 · February 2021

Really in terms of chain line you shouldn't be using the biggest sprockets on the big chainring.

If it was me I would simply switch to a 46, lower the front mech and give it a try.

N0bodyOfTheGoat · February 2021

Have a look at the cassette options at https://www.sheldonbrown.com/gear-calc.html and get one that covers a large range, that results in two tooth jumps in the smaller sprockets?

I have an 11-speed 11-34 on my Cube which does the above, which suits my needs as someone more intrested in climbing gear options rather than outright speed on descents...
11-13-15-17-19-21-23-27-30-34

pblakeney · February 2021

I'd imagine that getting a 14-28 cassette would be the best solution.
Ignores the smallest cogs, gives one extra easy gear, and smaller increments.

PMark · February 2021

I wouldn't bother changing your front gearing. I am assuming you are running the older 9 speed Tiagra, in that case just replace your rear Derailleur with a Sora R3000 GS one (as can accept larger sprockets) and then get a 11-34 9 speed cassette. I would also change your gear cable at the same time.

MattFalle · February 2021

focuszing723 said:
Really in terms of chain line you shouldn't be using the biggest sprockets on the big chainring.

If it was me I would simply switch to a 46, lower the front mech and give it a try.

really, in terms of chain line, its fine.

focuszing723 · February 2021

MattFalle said:

focuszing723 said:
Really in terms of chain line you shouldn't be using the biggest sprockets on the big chainring.

If it was me I would simply switch to a 46, lower the front mech and give it a try.
really, in terms of chain line, its fine.

The above graph illustrates a few things: Should a rider use the inner chainring on a 2X with any of the three smallest cogs, friction will be higher than it is when using the 1X. To achieve 2X efficiency gains, a rider must only use the inner chainring with the largest seven cogs. By contrast, the outer chainring of the 2X is more efficient on any cog than the 1X is in any cog. For riders seeking optimal efficiency, shift from the outer to the inner ring when shifting into the ninth-from-smallest (second-from-largest) cog.

https://www.velonews.com/gear/gear-issue-friction-differences-between-1x-and-2x-drivetrains/

https://www.bikeradar.com/features/friction-facts-free-speed-from-proper-shifting/

MattFalle · February 2021

Really, in terms of chain line, its fine.

simon_e · February 2021

lil.godzilla said:

That does seem to make some good sense...

Jut realised that I'd omitted the 14t from the 11-28 cassette so I was wrong when I said that cassette misses that very useful cog. Oops. Correct ratios courtesy of SJS:

11, 12, 13, 14, 15, 17, 19, 21, 24, 28

I'd suggest that it's more important to focus on the gears you'll use most of the time instead of the biggest gear you might want occasionally. After all, freewheeling downhill is fun.

dj58 · February 2021

OP, I have a 2013 Defy 10 speed, and have test fitted a 46/31T, it did not work because as you have eluded to, the baze on FD cannot be lowered sufficiently to achieve the required 1-3mm clerance to the outer chainring. Also IIRC the FD 4600/5700/6700 is not profiled to match a lower than 50-48T Chainring.

Try a CS-4600 12-28T, now CS-HG500-10, or CS-4600 12-30T, CS-6700 12-30T. If you want lower than 34T - 28/30T you can fit a 33T 110 BCD 5 hole inner chainring. If you are replacing your RD go for a RD-4601 SS or GS or RD-5701 SS or GS, RD-6700-A, if you can find one. RD-4700 SS or GS will not work with your current STI-4600.

My gearing is too high

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