10 speed 46t/30t chainset or 11-40 cassette ?

[Guitars and Bikes]

On my cannondale caad8 I have the full 10 speed 105 group set which includes the 50 / 34 chainset and 11-32cassette. Nearby climbs include a horrible 12% and a really horrible 18%, both are about 1km in length, and I just want to be able to spin up them at a comfortable cadence, as opposed to what I am doing now. Swapping my 50/34 chainset for 46/30 ( I am not really bothered about the reduction in top end speed ) or swapping my 11-32 cassette for 11-40, which of these two options would make the climbs more noticeably easier and more suited to a higher comfortable cadence ?
Thanks in advance.

 

[Jameshow]

If it's a long rear mech could go to a 36 on cassette without any other changes?

 

[Once a Wheeler]

I would swap the chainset as keeping the cassette sprockets closer in size should make changing smoother during the climbs. However, I doubt if there's much diference in the end.

 

[Tigerbiten]

Don't make the mistake of just focusing on the new low first gear, whilst it's nice to have you'll not really use it that often.
Workout what's gear you normally use on the flat as that you most used gear.
Plug your gear setup into a gear calc and see what the steps between the gears are like around you normal flat gear.
Now plug the new setups into the calc and see how the steps alter around your normal flat gear.
Does the 11-40 add a very wide step next to your normal flat gear and how well do you think you'll cope with it.
Some people hate a cassette with has a big step there and other don't mind it. I'm in the hate it camp.
So I'd probably go for the smaller chainrings and keep the narrower steps between the gears of the 11-32.

 

[bobzmyunkle]

10 speed 105 with 11-40 cassette? You'll need a long cage (9 speed MTB derailleur) and a derailleur extender, will you not?
As stated above, changing chainset will give lower gears without larger jumps between.
I just done both 46-30 and 11-40, but that's for dragging my camping kit up alpine climbs.

 

[fossyant]

I think you are pushing it going above a 32 cassette with a 105 long cage mech - I have 34 x 32 on my CX bike, with a long cage 105 mech, and it goes up walls (off road) so a 12% should be a doddle. 25% is never much fun anyway !

 

[roubaixtuesday]

To answer the direct question: it's just the ratio of the cog sizes, or you can use a gear inch calculator (this gives the effective gear as the size of Penny Farthing wheel and is the standard way to compare): https://www.bikecalc.com/gear_inches

By simple ratio:

34/40 = 0.85
30/32 = 0.94

So your 40 cog cassette will give you a significantly lower bottom gear.

As others have written, however, that might not be very practical. I suspect a 34T rear cassette and a 46/30 chainset would be the best option, not requiring special widgets or loose chains.

 

[GuyBoden]

On my cannondale caad8 I have the full 10 speed 105 group set which includes the 50 / 34 chainset and 11-32cassette. Nearby climbs include a horrible 12% and a really horrible 18%, both are about 1km in length, and I just want to be able to spin up them at a comfortable cadence, as opposed to what I am doing now. Swapping my 50/34 chainset for 46/30 ( I am not really bothered about the reduction in top end speed ) or swapping my 11-32 cassette for 11-40, which of these two options would make the climbs more noticeably easier and more suited to a higher comfortable cadence ?
Thanks in advance.

Quote: "or swapping my 11-32 cassette for 11-40"

Difficult, due to 10 speed 105 being for road bikes. You could change to an older 9 speed MTB rear derailleur. (Shimano Deore M591 9 Speed)

10 speed road bike and 10 speed MTB rear derailleur are not compatible. The 10 speed MTB rear derailleur needs more cable pull from the gear shifter.

I am current using a 40t rear cassette with a Shimano Deore M591 9 Speed derailleur, with the b-stop screw changed to a longer screw.

I use a gear hanger extender for a 46t cassette.

 

[robjh]

I think you are pushing it going above a 32 cassette with a 105 long cage mech - I have 34 x 32 on my CX bike, with a long cage 105 mech, and it goes up walls (off road) so a 12% should be a doddle. 25% is never much fun anyway !

I managed to fit an 11-34 cassette with 105 front and rear mechs without any trouble, although the Shimano tech docs seemed to say it was impossible. Not sure if I could go any bigger than that at the back, but I have a triple 50-39-30 up front so get a good low 30-34 combo for comfortable climbing with a bit of luggage on the bike.

 

[fossyant]

I managed to fit an 11-34 cassette with 105 front and rear mechs without any trouble, although the Shimano tech docs seemed to say it was impossible. Not sure if I could go any bigger than that at the back, but I have a triple 50-39-30 up front so get a good low 30-34 combo for comfortable climbing with a bit of luggage on the bike.

2T more is fine, but not a 40T as the top jockey won't cleat the sprocket.

 

[I like Skol]

It won't be long until one of these clever bicycle gear manufacturers comes up with the great idea of adding a third, smaller chainring to a chainset to allow suitable gears for climbing without having to resort to stupidly big, expensive cassettes with big steps in the ratios! They could call it a 'triple' and I reckon it would be really popular......

 

[All uphill]

It won't be long until one of these clever bicycle gear manufacturers comes up with the great idea of adding a third, smaller chainring to a chainset to allow suitable gears for climbing without having to resort to stupidly big, expensive cassettes with big steps in the ratios! They could call it a 'triple' and I reckon it would be really popular......

Calling @ColinJ who I'm sure could think of a catchy name for that. Tringlespeed?

 

[roubaixtuesday]

It won't be long until one of these clever bicycle gear manufacturers comes up with the great idea of adding a third, smaller chainring to a chainset to allow suitable gears for climbing without having to resort to stupidly big, expensive cassettes with big steps in the ratios! They could call it a 'triple' and I reckon it would be really popular......

Sora 9 speed is available and excellent, though needs a generic chainset to get below 30T at the front because shimano.

I think it's also not available in hydraulic or Di2, so you get the added bonus of not getting anything unnecessary on a bike so equipped.

 

[GuyBoden]

It won't be long until one of these clever bicycle gear manufacturers comes up with the great idea of adding a third, smaller chainring to a chainset to allow suitable gears for climbing without having to resort to stupidly big, expensive cassettes with big steps in the ratios! They could call it a 'triple' and I reckon it would be really popular......

I was riding along with a rider yesterday, he looked at my triple and he said jokingly "Triples are for old blokes" as he was grinding his way very slowly up a not very steep incline with his double.

 

[ColinJ]

Calling @ColinJ who I'm sure could think of a catchy name for that. Tringlespeed?

Hmm - 3 at the front, and 1 at the back... you might be onto something there!