Questions re lower gearing

deevemon · July 2017

I have a 2012 Jamis Quest road bike with the Shimano 10 sp. 105 group. I'm wanting to change the rear 11-28T cassette for something with lower gearing. The bike has 50/34 front chainrings.

I need lower gearing for these East TN hills. Shoud I change to 32t or 34t cassette? Will a 32t make much difference?

I'm trying to figure out which components I'll also need to replace if I change to a larger gear. I assume I'll need a replacement 10 sp. rear derailleur. Will my 5700 shifters need to be replaced as well?

Any info on needed components would be appreciated.

Thanks,
Dave

k-dog · July 2017

The shifters will be fine (as long as you are using the same number of gears) but your rear mech won't cope with that - you can just squeeze 30 as the biggest cog (they do a Tiagra 12-30) but I don'tthink 32 would work as the chain would be too long or too short at the extremes.

You'd need to change to a longer MTB derailleur to make that work. A 9 speed MTB derailleur would work - the pull ratio for 10spd is different.

That's quite a lot of gear though - I have used 12-30 with a compact chainset and I can get up anything (slowly!) 34/34 is going to be hard to stay upright and will give you a few big gaps in shifts.

pilot_pete · July 2017

Harsh as it may seem, you already have a pretty low set of gears and shedding weight/ getting fitter would be the way to go! The more hills you ride, the stronger on hills you will get, it's as simple as that. When I started out on a lowest gear of 34/25 I found hills, even small ones, hard. A couple of years later I managed to cross the Pyrenees from end to end on that exact combination.

Good luck!

PP

lesfirth · July 2017

I run 105 with a Tiagra 11/34 cassette. You need a later 5701GS rear mech and you have to mess with the B screw. Easiest solution is, as said ,use a 9 speed mountain rear mech.( Dont be confused you still use 10 sprockets).
I can assure you that you will not fall over because you are going too slow.
I could loose some of my 67KGS and I could be fitter, however going back in time 50years to my physical peak is not,much as I wish it was, an option. If you need some lower gearing to enjoy your cycling more get some.

joncomelately · July 2017

Is there room to sacrifice top end - as then you could just change a chainring and leave the cassette and mech as it is, maybe shorten the chain if necessary?

deevemon · July 2017

Thanks to all the responders so far. I agree that I need to get fitter, but getting fitter isn't as easy as it used to be at 64 yo. I am going to do more climbing though, so that will help.

After some more research, I've decided to go with a Tiagra 11-32 cassette and use a 5701 med cage DR. That'll be a pretty good jump. We'll see how it goes. Thanks again.

dj58 · July 2017

If your existing 105 RD is a 5701 SS model you could fit a CS4600 or CS6700 12-30T cassette, add 2 full links to your chain length and wind the B-tension screw in, and see how you go on, before you splash out on a new GS RD.

nellie72 · July 2017

Same topic but slightly different detail.

I run an Ultegra 6700 10 speed compact with an 11/28 block. Later this year i have a three day event with three ascents of Mont Ventoux. I would like to go to a 12/32 to make life easier but don't really want to have to get a new RD.

So, if i go for a 12/30 instead will I;

a) see a noticeable difference on the steep
b) have any problems with chain length?
c) need to make any other considerations

Thanks in advance!

rick_chasey · July 2017

nellie72 wrote:

Same topic but slightly different detail.

I run an Ultegra 6700 10 speed compact with an 11/28 block. Later this year i have a three day event with three ascents of Mont Ventoux. I would like to go to a 12/32 to make life easier but don't really want to have to get a new RD.

So, if i go for a 12/30 instead will I;

a) see a noticeable difference on the steep
b) have any problems with chain length?
c) need to make any other considerations

Thanks in advance!

What do you ride on the front? Standard or compact?

nellie72 · July 2017

Rick Chasey wrote:

nellie72 wrote:

Same topic but slightly different detail.

I run an Ultegra 6700 10 speed compact with an 11/28 block. Later this year i have a three day event with three ascents of Mont Ventoux. I would like to go to a 12/32 to make life easier but don't really want to have to get a new RD.

So, if i go for a 12/30 instead will I;

a) see a noticeable difference on the steep
b) have any problems with chain length?
c) need to make any other considerations

Thanks in advance!

What do you ride on the front? Standard or compact?

Compact.

rick_chasey · July 2017

Is fine.

I ride Ultra 6700 with a compact and i have 12-30 on the back.

34x30 is pretty low. Beyond that you're in MTB territory, and you gotta have some standards...!

With things like Ventoux you can always want a lower gear, but there comes a point where you just need to MTFU and get on with it. It's gonna hurt whatever.

nellie72 · July 2017

Rick Chasey wrote:

Is fine.

I ride Ultra 6700 with a compact and i have 12-30 on the back.

34x30 is pretty low. Beyond that you're in MTB territory, and you gotta have some standards...!

Haha. Well i am MTB at heart but loving the road at present.

So no derailleur/chain changes required??

rick_chasey · July 2017

Nah. All good.

Might need to take a link out or two; or add some in.

TBH, for £15 you can get a bike shop to do it for you, and if they screw up the indexing they'll keep fixing it till it's silent.

nellie72 · July 2017

Rick Chasey wrote:

Nah. All good.

Might need to take a link out or two; or add some in.

TBH, for £15 you can get a bike shop to do it for you, and if they screw up the indexing they'll keep fixing it till it's silent.

Good news, thnks

dj58 · July 2017

You can also fit a 33T inner chainring to your compact, I've read on here that a member did that when they went on an alpine trip. https://specialites-ta.com/plateaux/roa ... nring.html

Nick Payne · July 2017

Pilot Pete wrote:

Harsh as it may seem, you already have a pretty low set of gears and shedding weight/ getting fitter would be the way to go! The more hills you ride, the stronger on hills you will get, it's as simple as that. When I started out on a lowest gear of 34/25 I found hills, even small ones, hard. A couple of years later I managed to cross the Pyrenees from end to end on that exact combination.

Yeah, right, must be why riders in the TdF mountain stages were using 38x32 or 36x30 bottom gear.

N0bodyOfTheGoat · July 2017

Gearing is a very personal thing, it depends upon things like your fitness level; the gradient and length of the hills you are climbing etc.

I've not been for a for weeks now, but I was until then I was regularly visiting the South Downs, ~47-mile journey there and back over five cat4 hills (my longest ride ever is ~53 miles in a day). The worst of the cat4s was bang in the middle of my route, Butser Hill, which has numerous cat4 Strava segments that are anything from 0.6 to 2.1 miles long.
https://www.strava.com/segments/8217041
https://www.strava.com/segments/14331133

For me, who only started this modern fitness quest back in January, hitting this hill after ~22 miles and having already ridden up two cat4 hills is a real challenge... I'm in my lowest gear (34/32) trying to maintain 80+rpm up that final ~0.6 miles of ~10% gradient.
https://www.strava.com/activities/10500 ... /1918/2170

I'm sure that if you knew what cadence you climb your favourite hills at with your current lowest gear, there must be a way to calculate what cadence you could manage with a 30/32/34T easiest sprocket, aiming for 80+rpm (to reduce metabolite build-up in your legs before you continue on your way)... But I've never tried this method and I'm too "wooly" this morning to think this through.

PhilipPirrip · July 2017

I had a similar idea earlier this year as I was off to Norway to climb some hills so I swapped out the SS plates on the 5700 rear derailleur for GS plates. Along with the b screw modification and a new chain was able to run a 34T sprocket without problems.

Having gone to all that effort I was then a numpty and forgot to change to the lower cassette over before I went.

stormsedge · July 2017

E. TN here as well. Started riding seriously in January on my MTB with slicks while conducting frankenbike experiments on my old Schwinn Crosscut. Moved to Frankenbike when it was ready to come off the work stand retaining the 28-38-48 chainrings, but moving to 9 spd 11-32 cassette. Rode that one (including the 3S3M...thank you 32/28) until I began completing my training rides without going to small 28 chainring. Then purchased a "real" road bike with 34-50 compact and 11-32 cassette. Wordy I know, but your conditioning will improve and you may find the 11-32 has sufficient grunt for the hills. That said, I'll be seriously considering an 11-40 or 11-42 cassette for next year's 3S3M. Keep smiling...the bugs are protein.

Questions re lower gearing

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