caad12 gearing options

Discuss light weight issues concerning road bikes & parts.
scfc151
Posts: 8
Joined: Tue Sep 04, 2018 11:38 am

by scfc151

hi all.

just bought my 1st road bike a caad12 105 disc. it currently has a semi compact 52/36 fsa gossamer and 11/28 cassette.
im finding due to my lack of fitness at the moment that any gradients above about 15% im stuggling with.

i dont know whether to change the rear cassette but then id need a longer cage derailliur and chain, or change the crankset to a 50/34. if i do this and want to change to 105 i believe i need to adapt from bb30a to hollowtech2? this is all new to me so im still learning.

the other option for the future is ideally id like electronic shifting. so im trying to work about what the best option would be. for example would i be better putting an ultegra crank on if i have to adapt the bb to prepare for di2? or would sram red go into bb30a?

thanks all

by Weenie


TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

You could definitely fit an 11-30t cassette on the back without issue. You should even be able to run an 11-32t, but don’t take me word for it.

As for the crankset, swapping FSA Gossamer level chainrings isn’t that expensive...easily under $100 to do so. Keep the old chainrings in a drawer until you need them again.

Shimano crank spindles require 24mm adapters or full conversion BBs. SRAM crank spindles come in BB30 or GXP 24/22. The BB30 version should work with BB30A if you remove the preload adjuster and install a wave washer.

scfc151
Posts: 8
Joined: Tue Sep 04, 2018 11:38 am

by scfc151

i have seen fsa adapters fpr bb30a to 24mm for about £12 but in green that would look odd on my frame. im not sure if there are any other adapters available. would the 30 cassette go with a short cage? if so how does a 36/30 compare to a 34/28 in terms of climbing?

Bluechip
Posts: 115
Joined: Thu Nov 12, 2015 2:04 am

by Bluechip

A 34/30 combination is only a few gear inches smaller than your lowest now. I woulnd't change anything right now, but wait until it's time to replace because of wear. A few gear inches won't make that much difference on a 15% grade. Everybody struggles on those. Just keep riding and it will get a little easier (not much).

TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Every little bit helps, and he can always swap back to the 11-28t at a later date. It’s not like he has to dispose of the old cassette or old chainrings when he swaps.

scfc151, I’m extremely confident that the CAAD12 with a 105 short cage will handle an 11-30t cassette just fine.

BTW a medium cage 105 rear derailleur costs something like US$40.

Bluechip
Posts: 115
Joined: Thu Nov 12, 2015 2:04 am

by Bluechip

A 36/30 vs a 34/28 are nearly identical. Check out the gear chart. http://www.bikecalc.com/gear_inches Both are about 2 gear inches lower than your current 36/28. Not enough of a difference to change imo. Edit to follow rules. In both examples every pedal revolution would carry you 5 cm less in distance than your current setup.

scfc151
Posts: 8
Joined: Tue Sep 04, 2018 11:38 am

by scfc151

i must admit although the suggested gearing isnt too far apart from what i already have theres been a couple of occasions when i have felt i just needed an extra gear or two to get me up the big climbs.

i am only 5'8 with a 29" inside leg and have 172.5mm crank arms. because I feel my knees come up a bit high towards my chest when im in a more aero position i was considering switching to a shorter crank.

i was wondering if this would help me up hills along with a slightly easier gear in terms of cadence?

TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

If you switch to 165mm cranks, you will mostly nullify a switch from a 36t to 34t small ring.

07stuntin6r
Posts: 196
Joined: Mon Aug 08, 2016 2:09 am

by 07stuntin6r

scfc151 wrote:i must admit although the suggested gearing isnt too far apart from what i already have theres been a couple of occasions when i have felt i just needed an extra gear or two to get me up the big climbs.

i am only 5'8 with a 29" inside leg and have 172.5mm crank arms. because I feel my knees come up a bit high towards my chest when im in a more aero position i was considering switching to a shorter crank.

i was wondering if this would help me up hills along with a slightly easier gear in terms of cadence?
Interesting as I'm 5"8 with 32" inseam. I notice myself as well that when I'm resting my forearms on my bars to get.more relaxed and aero I feel my knees come up high also with 172.5 stock cranks.

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TobinHatesYou
Posts: 4175
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

I’m 5’10” and currently experimenting with 165mm cranks. They’re great for flats, but I’m not sold on them for climbing, even with a 34x32 low gear.

07stuntin6r
Posts: 196
Joined: Mon Aug 08, 2016 2:09 am

by 07stuntin6r

TobinHatesYou wrote:I’m 5’10” and currently experimenting with 165mm cranks. They’re great for flats, but I’m not sold on them for climbing, even with a 34x32 low gear.
I live in Fl so all I got is flats haha

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scfc151
Posts: 8
Joined: Tue Sep 04, 2018 11:38 am

by scfc151

07stuntin6r
are you goin to shorter cranks?

07stuntin6r
Posts: 196
Joined: Mon Aug 08, 2016 2:09 am

by 07stuntin6r

scfc151 wrote:07stuntin6r
are you goin to shorter cranks?
Not sure was going to ask once I get fitted if I should or not....was going to go with 172.5 but now I'm wondering how much smaller I should go.

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2lo8
Posts: 539
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

TobinHatesYou wrote:
Tue Sep 04, 2018 12:14 pm
As for the crankset, swapping FSA Gossamer level chainrings isn’t that expensive...easily under $100 to do so. Keep the old chainrings in a drawer until you need them again.
Probably cheaper to just buy a take-off or shady OEM crankset off ebay. That's the issue with Shimano cranks too. It's often cheaper to buy a new crankset than source chainrings.
scfc151 wrote:
Tue Sep 04, 2018 2:13 pm
i am only 5'8 with a 29" inside leg and have 172.5mm crank arms. because I feel my knees come up a bit high towards my chest when im in a more aero position i was considering switching to a shorter crank.
Shorter cranks will lower your leverage for climbing though. Still, shorter cranks do help with the top dead center issue. I pretty much refuse to run anything but 165mm on my bikes. Are you sure you're measuring inseam correctly (book method or whatever)? 29" for 5'8" is very very very short. If you have noticable TDC problems then you should try a full 5mm shorter (this will raise your knee 10mm less), not 2.5mm. Since 167.5mm is rare, I'd err to 165mm rather than 2.5mm which will only have a marginal difference if you have noticble crank length issues. The normal 165mm-175mm crank range is nowhere near the actual range of leg lengths, so I wouldn't worry about going too short if you are actually having problems.

My view on crank length is 2.5mm increments don't make much of a difference, they just exist because it looks pro to have 2.5mm increments and is splits the difference between 170mm and 175mm crank bikes with OEM cranks and makes it so there isn't a sudden step in the middle of your bike size range to include more people under the bell curve. If your optimal crank length is 172.5mm, you won't have issues running 170mm or 175mm. If crank length is a noticable issue, there's nothing wrong with jumping a couple of sizes because it's a big enough issue where you're probably off by more than 2.5mm.
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scfc151
Posts: 8
Joined: Tue Sep 04, 2018 11:38 am

by scfc151

thanks for the replies. im keen to try a 165mm crank length. just dont wana spend a load of cash committing to it if its wrong. off to the lbs for a fit maybe

by Weenie


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