cyclezen

I'm not sure how you could even start comparing between the 2 bikes... 42/28 + 5lbs vs 34/28 ?
Ok, 5-6% grade isn't much, but I was trying to put into a frame work which I see a lot of riders struggling. But let's make it 'real' 8-9%+ and, for whatever reason, you're barely turning 55/60, on a current bike with 34/28, 25mm rubber - you're goin about 9 kph (6ish mph) - you drop into a 30 or 32 - I would put big money that, after about a 20 yd surge, you will again be doing 8 kph.... and happy that you haven't put a foot down. WHy do I say that?
Well, if you're at 65-70 rpm, you're getting into a new, lower effort comfort zone. If you're at 55 rpm, you're already DONE/cooked and 30/32/34 isn;t going to save you - you'd need 40/42/48 to find relief... Reality is a *****.

Ride On
Yuri

big john

Actually what he asked for was both higher high and lower low. He also mentioned coming from a flat area and moving to a hilly area. Before buying parts it might be to his advantage to try and stay with his current gearing for a time, to see if he even needs to change it.

It might help him to hear that experienced climbers who are older, heavier, and in questionable condition (me) climb and descend hundreds of thousands of feet each year with more limited gearing than he already has. Or maybe not.

xroadcharlie

I once thought that using my lowest gear of 21 gear inches was more effictive for me to climb a steep hill with soft gravel on my comfort bike. Certianly for the steepest parts of the climb this is true, But on less steep but still challanging sections I found shifting up a cog or two (to 30 gear inches) to be best. For me keeping a cadance of about 60 rpm seems to work best climbing. Its Strange that on a flat 70 - 75 rpm seems to work well at medium high effort.

Regardless, I want the right gear for the job. IMO if a gear change to a 46/30 chainring gives the op the gearing that works best for him, Then it is a smart move.

cyclezen

Respectfully, I agree that anyone who has angst about effort, should take all precautions they feel necessary.
If I keel over on Gibraltar some day, c'est la guerre...
BUT, we can only comment on what info the OP puts in his Q.
Truthfully at 40 rpm, dropping into the next lower gear is not gonna do it.
... Get the 11/32 or 34 cassette, but then go put the work in.
Ride On
Yuri

HTupolev

It's pretty simple kinematics, and 5lbs is usually a small enough difference to total system weight that even rough approximation can paint an accurate-enough picture to address the question.

For instance, if a bike+rider is 167lbs, a 5lb increase represents a 3% increase in resistance from gravity. So for example, on a steep climb where you're going slow and bottlenecked by gearing, that 42T chainring on the Miyata would be like using a chainring slightly larger than 43T on the Emonda.

Why are we assuming that the rider will "surge"?

What point are you even arguing? I mean, obviously if your legs want to climb at 70rpm, and your gearing currently pegs you doing a lot of 55rpm, going from 28T to 32T may not produce a totally-optimal situation. But it's still an improvement, and if a rider wants even lower, they can set their bike up with even lower: the OP's question about lowering gearing was quite open-ended.

genejockey 

Sounds like he's shopping for a new stereo.


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seypat

I weigh around 200lbs. A 10lb loss or gain is equal to a 1 cog change of the big cogs.

urbanknight

This might require that the OP buy a subcompact crankset. Not super cheap, but it would be effective (assuming you take the above advice and just coast down fast descents).

You could probably throw on an 11-34 cassette without any other changes, but it would be a tiny difference.

urbanknight

Is there a source for this? It seems way too round of a number and way too linear of an equation to be anything but made up.

big john

Pretty sure the OP isn't coming back.

seypat

Just my experience in the past with weight variations climbing the same hills.

koala logs

40 rpm indeed a point of great struggle. It may feel significantly easier if you can spin at least 60 rpm which likely means a gearing change.

Another option is just buy a gravel bike with super low gearing, 46 to 30t chainring and 42-11t cassette. Gravel bikes also have endurance geometry like your Giant Defy.

I don't really pedal on a 5% gradient descent or more. If you have tight fitting clothes, just tuck it in and it will get you to 60 kph.

datlas 

Agree. But it won't prevent this thread from dragging on. It may even come back in 10 years as a zombie!

#41

seypat

Maybe not, but he/she'll probably be looking at it from time to time.

Road Fan

@Barrettscv, My reply was intended for the OP, who seems to have gone away, not to you. I was stimulated to add by your response to him. To add a bit, some cycling training experts, such as Joe Friel talk about different types of fitness and what they mean. Friel wrote a nice book called “Cycling Past 50.” He describes it as a ”high level of endurance that relates to the muscles’ ability to cope with the fatigue associated with the buildup of lactate and the depletion of glycogen.” These last two effects are what happens to your muscles when your are for example climbing more difficult terrain for a longer time. When your thighs and perhaps glutes burn, your breathing may not permit you to speak a few words, much less have a conversation.

I am nearly 69 and no paragon of fitness or training knowledge, but in the past year I’ve decreased my weight from 207 to 197, reduced BMI from 32% to below 28, and increased lean mass to 138# from 125#. Before this I had burning legs on our local hills (Midwest USA is pretty flat compared to the Rocky Mountains, but still pretty flat), and now my 50/34 11/29 lets me ascend it with about 60 rpm, 7 mph without going anaerobic. The breathing performance alone is aerobic endurance, but adding the load of climbing makes it muscular endurance. The improvement was based on more and harder yoga, more indoor pedaling, a lot of housework and home rearrangement in a house with three flights of stairs.

When I tell my doc I want to kick up my cycle training, she thinks not about my max HR, but about whether my heart is functioning well under physical stress. While I use an HRM, I’m not oriented at the moment to zones and levels. Pushing your heart rate might be ok for you, but if you are using a number just calculated from a simple formula or chart based on age as a firm limit, that is probably not a good practical (or productive!) limit for you.

genejockey 

"I'm building a C&V bike with a carbon fiber frame and first-generation 105 Di2, but the only 12 speed cassette I can find is 11-34. Can I fit a 48t cog to go with my 20t small ring? Will the derailleur work? And can I use my 15 speed chain with it?"

xroadcharlie

I just looked up a decent appropiate 46/30 crankset. I thought they'ed be less expenive. And yes, to spend that kind of money on my $500 Giant Sedona seems high. But where talking about a CDN $3,000+ bike. A very good bike at that, So in this case I think it would be a very good option.

We could use a wide range cassette and new proper derailuer that might cost the same. But I really like the closer ratios on the stock cassette.

koala logs

I find this suggestion unusual. I read a cycling fueling article and experienced for myself if fueling is limited and you want to last as long as possible on a ride without stopping, low intensity effort is the key.

Low intensity efforts gets you into fat-burning mode if carbs are running short and you'll be able to last much longer if burning body fat. Higher intensity efforts will get you into protein-burning mode, if carbs are low. Burning protein will cause early fatigue and hamper recovery post-ride. Strictly in terms of fuel economy, low intensity efforts are better and if fuel is limited, you'll get farther with lower intensity efforts.

That is one reason why the majority of the training time allotted for polarized training is at low intensity effort. Mainly for endurance adaptions without imposing too much on recovery.

On long 6 hr rides in the mountains without stopping, I "carbo-load" the day before and shortly before the ride and bring a fixed amount of fuel. If I work hard enough, I'll bonk the ride mid way and be forced to stop to refuel like ice cream and pepsi. But if I take it easy enough. I'll make the 6 hr ride non-stop and still have plenty of energy left for a sprint on the last 200 m distance from home.

HTupolev

It makes sense as a very rough approximation across some common road cassette sizes.

200 pounds, plus say 20 pounds of bicycle, means that a ten pound difference is something like 230 vs 220. That's a 4.5% difference in gravitational resistance on the climb. In reality, the total resistance is going to change by a bit less than that because not all resistance while climbing is gravitational (i.e. there's still some stuff like aero drag).
Meanwhile the difference between a 24T cog and 25T cog is ~4.2%, or the difference between a 27T cog and 28T cog is 3.7%. So these 1-tooth gear ratio changes are in the same neighborhood as the difference in resistance caused by adding 10 pounds on a climb.

The approximation will break down with less traditional arrangements, like if the road bike in question is running a 1x setup with an 11-50 cassette. Then a 1-tooth difference is a 2% change to gear ratio, for instance.

urbanknight

so this only works at the large end of the cassette? Because 11 to 12 is more like 9%. And we’re only talking to Clydesdales? Because 10lb to a 120lb rider is more like 8%

HTupolev

Seypat's comment about "big cogs", plus the reference to weight, made it sound like they were referring to what their bottom-end gears were worth on a climb.

Yeah, the comment referred to a 200lb rider weight.

I don't think Seypat was intending for the formula to be generalized.

seypat

Correct. 200 to 210, need 1 more climbing gear. 200 to 190, 2 less climbing gears than 210. On 9 speed 11-28 or 11-30 cassettes.
BTW, that's 5'8" 200, so I really can't give recommendations on "ride or feel." Something like tires or frames are going to feel completely different to me than to a 5'8" 130 or a 6'3" 200 rider.

koala logs

I can vouch for the fact that you are right. I get rather significant improvement in climbing speed if I switch to a lightweight bike at my weight of 124 lbs.

My bike weighs in at 40 lbs with one bottle of drink and the tools and panniers and fenders and all that but had easier gears for climbing loaded on mountains.

Then a I tried a friend's bike weighing only 20 lbs, what a world of difference!! I climbed the same hill at higher gear, higher speed and didn't even feel like I'm climbing! Fu** is the word for it!! Only wished I can afford the same bike he had!

Actually, the % difference in performance can be a lot higher if the effort is above lactate threshold just to get things moving like a in a steep climb and then goes below with equipment changes. It allows you to do intervals to alternate pushing or getting rid of lactic acid build up or maintain constant effort around lactate threshold with a lot less suffering. It can mean a large improvement in average speed in a climb, well beyond the % difference in equipment offered like the weight or gear ratio. In my experience, reducing bike weight is more straightforward approach because it directly translates to reduced power requirements. Switching to easier gears may not. Power requirement would be the same but the easier gears would allow you to ride slower or strain your legs less but you can still blow it up if not used to the power level.

seypat

I think koala legs stated in one of these threads that he's around 173cm/68inches tall. If you were to give us the same bike to ride and evaluate, you'd get 2 totally different opinions. That's what makes the world interesting.

koala logs

Yeah, that would be the case! At GCN they talked about it in one of their videos with Emma Pooley on it. Because she only weighed 106 lbs, they commented how the bike's weight would make a much bigger impact to riders like her. You can't go cheap if you are that light! Or go cheap and heavy and limit yourself to slow speeds like I do!