deacon mark

I have a compact 34-50 with 11-23 rear. Works great here in Illinois. Going to Cadillac Michigan next week a few climbs do it before but wonder if going to 11-25 is worth it for a week of riding. I am a pretty strong rider but not great climber so my bailout gear 34-23 vs 34-25. Swap it have buy another cassette or just suck it up and mash up the few longer grades. Give some advice. Going to 28 rear not because chain would need to be swapped.

10 Wheels

Go for 12/32...Mine worked Great

TrojanHorse

2 teeth? Not much difference there but maybe enough to keep you from crying on a long hill.

Chains need to be replaced periodically anyway, I wouldn't let that stop you from getting something like a 12-28... you can always prune a link out of the chain later, and with a removable link you can switch between chains very easily.

PepeM

23 to 25? Probably not worth it. Going to 28-32 would probably be a better option, but I don't know what type of hills we're talking here. Chains are not too expensive and you could keep the chain for whenever you want to use the easier gearing again.

RJM

I would switch it to 11x28 and replace the chain. Two teeth isn't really worth it, IMHO.

therhodeo

Are we talking about rollers or stuff that you're going to grinding away for hours at a time on?

Bandera

One great advantage of modern cassette gearing is the ability to quickly and inexpensively swap gearing to match a rider's current terrain and fitness.
Experienced riders will often have Flats, Rolling and Mountain cassettes to change out as required.
Chains are wearable and should be replaced on a schedule that allows swapping cassettes w/o wear compatibility problems and long enough to accommodate the widest range to be used.
Shimano cassettes of any 10 or 11 cog series are interchangeable, a 4700 rarely used wide range will work just fine for few $ on a bike that normally runs 6700.

Having the low/low that one can climb the stiffest hill w/o undue stress and the highest that one is willing to spin out on the down side is optimal gearing, which changes w/ terrain and conditioning.
Gearing is a personal preference, having options makes sense if travelling to a different terrain.

-Bandera

deacon mark

The chain now is almost new. I do have a 12-25 but I want an 11 on top. The ski lodge has one climb about 6-7% for about I mile. It probably averages a little less. I just remember 2 years ago I got up fine but hate to struggle. I guess this will not make it much easier my fitness is fine plenty of wind just no real hills around here to compare. I just want go up on down that hill to see if I can get some speed going down. I chickened last time at 37 mph probably good enough to get near 46 but have to work on that

Kopsis

I'm going to take a dissenting opinion and say that 23 to 25 might very well be worth the price of a cassette. 2T at those sizes is about a 9% reduction. You might also look into an 11-26 (a 13% reduction) if you have enough chain to handle it.

CliffordK

Many of the classic road bikes came with something like a 52/42 and 13/23 or so, and could climb hills just fine with the right rider.

It depends on the hills you're hitting (length, slope), baggage you're carrying, and whether you stand and pull up on hills.

How old is your chain? Stretch? You can always swap chains, and keep the old one as a spare. People also recommend a new chain with a new cassette... so you don't grind it down too much too quickly.

Drew Eckhardt 

It depends on your weight, mean maximal power curve, tolerance for lower cadences, required freshness after the climbs, hill grade, climb length, etc.

The 30x21 I used worked great for a week spent riding 418 miles and 28,000 vertical feet between Grand Junction and Golden, CO. 34x23, 39x26, and 42x28 are all close enough to work as well. With nearly 50 pounds of middle-age spread but otherwise similar fitness I'd need a 29.

You're in a much better position to figure out what will work for you than the rest of us. Estimate the power you comfortably produce in similar duration climbing situations using Strava and dump that into a calculator like Analytic Cycling's speed given power page. Only use steeper hills because power requirements there come almost entirely from your weight and speed which are known versus flat ground where it's largely aerodynamics varying radically and unpredictably between riders with a significant rolling resistance contribution that can be 50% higher from slow tires. Take speed in meters/second, multiply my 60,000 to get mm per minute, and divide by (3.14 X 622 + (2 X tire width)) to get rear wheel RPMs. Divide that by the cadence you want to get the gear ratio. Divide your small ring by the ratio to get a cog.

Example:
160 pounds of rider/bike/water / 2.2 = 73kg
73kg at 220W yields 3.6 meters/second up an 8% grade.
3.6 meters/second * 60 seconds/minute * 1000mm/meter = 216,000 mm/minute.
216,000mm/minute / (3.14 * (622mm + 25mm * 2)) = 102 rear wheel RPM
102 RPM / 70 RPM minimum desired seated climbing cadence = 1.45
34 ring / 1.45 = 23 cog

Chains are wear items you eventually need to replace. You won't spend appreciably more money buying a new one now, getting the rest of your miles out of your current chain some time after you switch back to the smaller cassette, then getting the remaining miles out of your new chain. You won't spend any more money if you've been planning ahead and already have the next chain you bought ahead of time from a low cost (potentially British) source.

OldsCOOL

As a Michigander (1.5hrs north) go with the gearing your bike can handle. Up here we have hills on every route. Hope you enjoy your trip!

banerjek

Go wider if you can. 34/50 with 11-23 gives little overlap right around the speed a lot of cyclists ride. I don't know what you consider a longer grade or your level of fitness, but 34/23 is not much of a climbing gear. If we're talking short climbs with hundreds of feet or just a few thousand feet overall that aren't on a horrible grade, you might be fine with you have if you're reasonably fit.

The trick with climbing is that you don't get to rest. You can last quite awhile, but once you burn up those muscles, you're in for a world of hurt. I'd recommend getting the new cassette and the chain. When you finish the climbing ride and swap out your cassette, just put your old chain back on. Many people keep a separate chain for the different cassettes so they wear together, but if you don't want to do that, you should size all subsequent chains for the larger cog. It's not like a chain with an extra link or two won't work with your small cassette -- don't forget that every combo on it is within the range of a larger cassette.

generalkdi

You can ride up 15 or 20% with that kind of gearing if you are a decent cyclist. If you want to go into steeper, I would change for something like a 12-27 or 11-28. (depending if you like big gaps in your cassette or not, I myself prefer 12-27)

smarkinson

Any reason why you can't swap cogs between your current cassette and the 25-12 that you have? So you can make a 25-11 cassette from your two existing cassettes.

bikepro

Going up to a 12/32 will certainly require a new chain. It may also require a new RD depending on the capacity if the current one.

banerjek

To ride 60 RPM at 15% on 34/23, you have to sustain 400 watts. So for BF purposes, this would be almost ideal gearing.

Those wishing a higher cadence and/or to last a bit longer might want a bigger cog in the rear.

TobinH

Yes, I think this is worth the price of a cassette. The right gearing can make a big difference to your enjoyment of the trip, and cassettes are consumables anyway.

GuitarBob

deacon mark

Well it is a done deal. I bought 11-25 the LBS had one so I just went for it. I can use it on my other bike too which is a standard double. I run a 12-25 on it so now I can add the 11 on the top. I did try an old cassette to piece together an 11-25 but it did not work. I have my own wheels I built ( BDOP DIY) they are 11 speed wheels but with a spacer I run my current 10 speed set up. I could not get the older cassette to piece together without a spacing problems on the wheels. Going to a new 11-25 cleared that up.

I am pretty decent wrench do all my own work and wheels, but sometimes rather than try and make things work I just go with what works. Strange is the I do not fear the long grade but I want to work on my descending with confidence. My thought is I can just keep going up and down this particular grade so that after a few runs I can handle some more speed on the descend. I was thinking of I have to work too hard going back up I will get wipe and give up. The old marathoner has wind but steep grades are always a challenge when you live in the flats.

bruce19

With my compact crank I went from 12x27 to 11x28 and it has made a great difference. Not so much with the 27 vs 28 but with the intermediate low gears.

macca33

Gold!!! I often wonder why all these 'Pro-riderss' are on here and not out training...

Jiggle

I bet your chain would be fine with the 28 as long as you didn't do big ring big cog.

generalkdi

At 129lbs I can ensure you this is way sustainable and is nothing "pro". I go up 25% with my 34-27 without problem, so I'm pretty sure I could go up 15% with 34-23. I'm far from being a strong cyclist at around only 2.5k per year.
I didn't say anything about 60RPM, I usually go around 50-55 cadence around theses grades.

data? https://www.strava.com/activities/32...ysis/2274/2480

And I'm still far from the first time which was done on a 54-25 on that segment (but by a much more than decent cyclist)
________________________________

With that said, I'm pretty sure he won't encounter that many steep gradient and should be good with his current setting.

JohnJ80

Having grown up cycling in and around Chicago, it basically qualifies as pancake flat. I'd go with an 11-28 or 12-28 for Michigan. It's going to be a lot like where I cycle now in MN - rolling hills with some steep grades at times but hardly ever just flat. I used to ride a 11-23 in Chicago and after leaving there, never used it again.

11-28 is great because the top half of the cassette through 19 is basically like the 11-23 with single tooth spacing. When you get to the last three gears, it separates by 2 or 3 to give you great climbing ability when you need it. On 11 speeds, I'd use the SRAM version - it will work on shimano drive trains just fine - because it has a longer run of single tooth separated gears than the Shimano version.

J.