# gear ratios and hill climbs



## gbs (1 Jan 2009)

Having been successful at hill climbs on a Marin hybrid with fat tyres I have been shocked by my poor performance on a lightweight Bianchi with 23c. The only negative characteristic of the Bianchi is the v high gearing; lowest gear ratio is 40:23 = 1.74. The comparable hybrid ratio is 0.81 (26 on the chain wheel and 32 on largest rear derailleur). I am considering changing the 2 chain wheels to produce a bottom gear that approximates 1:1 and possibly going for longer cranks to increase power. Does any one have advice for this 66yr old reasonably fit novice?


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## RedBike (1 Jan 2009)

The Bianchi will probably be *39*/23, not that it makes any difference. 

The cheapest option is to switch the cassette at the back. Without making any major changes (just a new chain) you can probably get away with cassette that has a 27 tooth sprocket. (You will need to get your LBS to check this is within the limits of your current derailleur.)
This will give you 39/27 =1.7

To get any lower than this is going to be costly. You will either need to fit a 32/34 casseette, change to a triple or compact chainset. 

The 32/34 Cassette will involve switching your rear mech to a MTB mech and a new chain. This will give you a bottom gear of 39/32 = 1.2

The triple will involve changing both the front and rear mechs (You may also need a new bottom bracket, cables and gear shifters; and while you're at it you might as well fit a new cassette. 
The bottom gear will now be 22/27 = 0.8


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## jimboalee (1 Jan 2009)

1st question...

What gradient are you riding up?

39 x 23 is a 44" gear, so you have a gear to get up a 10% on a sub 22 lb bike.

For comfort - My 16.5 lb SWorks Spesh has a 39 x 25 lowest, and I got off and pushed when I recce'd Saintbury. I'm a fifty year old club rider.

2nd question...

How far into the ride did you climb the hill? Was you properly warmed up?
Strangely, its the second or sometimes third ride up the same hill that is the easiest.

RedBike's advice on the 27 sprocket is a goodun, but you might have to build the cassette custom.


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## butki55 (1 Jan 2009)

Being a begineer and staying in the begineers section for begineers advice and tips. Could some one tell me in Lamens terms......heres looking at both jimboalee and RedBike what all that means numbers and stuff? 
I aint got the foggyest what that means.

Sorry if im I right one.

butki55.


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## RedBike (1 Jan 2009)

Sorry Butki55. 

The first figure is the number of teeth on the smallest chainring (The gears at the front.)
The second is the number of teeth on the largest sprocket of the cassette (The gears at the back)

You then divide one by the other to get the gear ratio 

A gear ratio of 1 means that everytime you turn the pedals one revolution the wheel will rotate once. A gear ratio of 2 means that for every half turn of the pedals the wheel will rotate once. Obviously the lower the gear ratio the easier it will be to climb a hill.


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## Euan Uzami (1 Jan 2009)

in addition to what redbike says: obviuosly a triple is the best option. however it may mean changing your front mech and shifter, but if you can afford it like i say would be the best option.
Shifters/cables: You wont' need new cable outer, and shifters normally come with inner - however shifters are quite expensive (like 3-figures normally, that said mine are 'out-of-the-back' oem 105s that i got for a bargain £40 a pair new, so hunt around - also try ebay for second hand ones).
Front mech: a chance that it will 'just work', although it may be the case that triple front mechs have more travel than double ones, so you may need a new one, that said front mechs aren't that dear. (like £20?)
Rear mech: likely need long cage, but try it first with the new setup to see if it shifts ok into all the usable gears.
Rear cassette: with a triple, you may not need to change the cassette aswell to achieve the ratios you need, and if the bike's fairly new then you may not need to change the chain, so therefore could get away with also not changing the cassette.
So, plan: hunt for bargain triple LH shifter, and triple chainset, fit them. Set up existing front mech. If it doesn't work because not enough travel, get triple front mech. Repeat. Check rear cassette shifts onto all usable gears. If rear mech is short cage and is struggling to cope with variation in length of chain, change to long cage, that should be it.

HOWEVER: getting a compact chainset instead of a triple may avoid you having to upgrade to a 3-speed shifter and front mech, if that's important to you and *may* avoid you having to upgrade to long cage rear mech. It will likely take your lowest front chainring down to ~34 instead of ~30, so you may want to go to a 12-27 instead of an 11-23. However so i've heard, with doubles you dont' get as much overlap and are more likely to have to run a small-to-small or large-to-large, resulting in not as good a chainline.


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## gbs (1 Jan 2009)

Well, I am almost overwhelmed by the number and depth of response - thankyou to everybody. The hill is a sort sharp tester of about 15% (does any one have a more accurate view?) in Richmond park btw RH and Kingston Gates. Jumping off and walking in cleats is a skill too far!


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## Euan Uzami (1 Jan 2009)

gbs said:


> Well, I am almost overwhelmed by the number and depth of response - thankyou to everybody. The hill is a sort sharp tester of about 15% (does any one have a more accurate view?) in Richmond park btw RH and Kingston Gates. Jumping off and walking in cleats is a skill too far!



15%, you are standing up out of the seat (honking) i presume? you get a lot more torque through the cranks that way.


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## yenrod (1 Jan 2009)

>Gear ratios and hill climbs

I select 'generally easy' gear on a hill.

The best idea with a hill is to be in the gear you can be SPINNING at the top. So go up 2-3 gears and see how you fare up and over the top...as you get stronger you can go up 1-2 but its definately better to spin!


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## gbs (1 Jan 2009)

*CRANK LENGTH and further comment re ratios*

Sorry to sound like a nag but no-one has commented on my question re length. Does more necessarily mean better? Current length 175mm (I think)

Researching manuf websites suggests the typical road bike low gear ratio is about 1.5x (my "difficult" Bianchi is at 1.70x) although I did spot a Cannondale Synapse at 1.26x. So my thought that I might lower to the ratio to 1.0x is entirely out of order and maybe I need more conditioning.

Yes, I do try to spin and honk - but not when driving in Richmond Park - must not disturb the deer!


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## Euan Uzami (1 Jan 2009)

more will theoretically give you more torque, so easier for a given ratio (like a lower gear), but probably very little difference, as it's only 5mm. most common i think are 165mm, 170mm and 175mm. all my bikes are 165 iirc.


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## rickangus (1 Jan 2009)

Regarding crank length. 

I've studied this in an amateur-ish way for a while, having longer legs than average. I'm 6' 5" so not huge but taller than most. The almost universal view is that the ideal crank length is a function of leg length and it isn't difficult to see why. The legs are the only moving part of the cyclist's engine and there are various analogies that can be called upon to demonstrate if nec... 

Although there are different formulae to calculate crank length they all seem to conclude that the perfect size is 21% of leg length. But it is important to understand what is meant by leg length. It is not the leg length of the trousers you buy! It is the length from your sit bones to the floor. Probably the easiest way to identify this is to measure your overall height, without shoes in metric. 

Then sit on the floor, back to the wall and measure your sitting height. Subtracting the sitting from standing height will give you your leg length. From that you can calculate your perfect crank length.

Are you particularly tall or short?

Obviously the human race has a wide range of heights and component manufacturers can't address all of them. If you fit within the 170/175mm range you are very fortunate. If you don't, you have to compromise - or fork out on some custom cranks. Do a google.com search and you will find a few suppliers in the US but the current exchange rate doesn't help.

Standard issue cranks are 170/172.5/175mm and you can appreciate that the difference is almost negligible. I actually use cranks that are 200mm and many folk gasp in amazement as they seem so much longer. Actually, it's only about an inch and they offer me a lot more comfort and I think greater efficiency but that is difficult to measure or prove. 

In summary, cranks that are too short lose you comfort and efficiency but you should be mindful that cranks that are too long will eventually hurt your knees and may even harm them.


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## gbs (3 Jan 2009)

Thanks for the comments re crank length. At 188cms height and 94cms sitting height, my 175mm crank length falls short of the 21% suggestion from Rick. I will investigate suppliers.

Meanwhile having established that the hill in question certainly exceeds my 15% guessestimate and may be close to 20% I will establish another thread to see what views others have of appropriate ratios


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## Steve Austin (3 Jan 2009)

GBS, your cranks are fine. crank lengths is one of them often debated cycling red herrings. 175 is fine for most cyclists
simply put:
shorter cranks are easier to spin
longer cranks can give more leverage

any more words will just confuse the issue

As for gearing. You would benefit from 12/28 cassette.


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## jimboalee (3 Jan 2009)

I checked out a Sram cassette. I ride a 12 - 23. Sram have a 12 - 26 listed, ChainReaction £24.
Going to LBS to count the intermediate sprocket sizes to see if it lies in a smooth gear progression with my 52 - 42 - 30 tripple.

For MTB use, they have a 11 - 32 and 11 - 34 
The upper jockey wheel will be pressing the chain onto this size sprocket on a road derailleur.
I've been there. I fitted a 13 - 28 on an old road bike. Its a bit noisey, but worth the lower gearing on the North Devon coast road. Not the thing for everyday, just for when demand dictates.


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## Cranky (3 Jan 2009)

jimboalee said:


> I checked out a Sram cassette. I ride a 12 - 23. Sram have a 12 - 26 listed, ChainReaction £24.
> Going to LBS to count the intermediate sprocket sizes to see if it lies in a smooth gear progression with my 52 - 42 - 30 tripple.
> 
> For MTB use, they have a 11 - 32 and 11 - 34
> ...



Hi jimboalee, I use the Sram 12-26 with a 52-42-30 triple myself. It's an excellent combination IME and the Sram cassettes give a very smooth change, too. I also use Sram 11-32 on my MTB.


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## butki55 (4 Jan 2009)

RedBike said:


> The first figure is the number of teeth on the smallest chainring (The gears at the front.)
> The second is the number of teeth on the largest sprocket of the cassette (The gears at the back)
> 
> You then divide one by the other to get the gear ratio
> ...



I know that I am on a MTB as im just getting into this cycling....and may I say the time I have been out its great. I have counted me teeth on the above sprockets as you said and my front small was 24 and the rear large was 34. Is this then a 0.7 or a 1.4. What does this mean for me riding this setup? What are the pros and cons for me.


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## gbs (4 Jan 2009)

To butki55; as a novice maybe I should not offer advice but since I started the thread I should show the kind contributors that I have learnt something.

I would say F/R 24/34 gives 0.71 ratio a v low gear ratio designed for difficult terrain (gradient and mud)


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## RedBike (4 Jan 2009)

> I know that I am on a MTB as im just getting into this cycling....and may I say the time I have been out its great. I have counted me teeth on the above sprockets as you said and my front small was 24 and the rear large was 34. Is this then a 0.7 or a 1.4. What does this mean for me riding this setup? What are the pros and cons for me.



It is a ratio of 0.7. It means that it is a very low gear compared to the bottom gear of most road bikes. Although, irronically it's not as low as most MTBs. Most MTBs have a 22 sprocket at the front! Im guessing the bike is acutally more of a hybrid?

It means that using this gear you'll have to pedal MUCH quicker than someone on a road bike in order to keep up (Probably almost twice as quick). However, you should be still going long after the road bike rider is pushing. It is also low enough to enable you to cope with a bit of off-road riding.


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## butki55 (4 Jan 2009)

Thanks to you both for that I thought it would be the lower number as it is a MTB and therefore making it easier on trails or off road terrain. 

Well I have to put up with it for at least this month as I am not intending to invest in anything untill February (My date). This gives me time on the bike, to see if one I will still enjoy it then. 

The problem of course will be when I want to invest in new/second hand road bike and getting used to the new ratios. 

butki55.


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## jimboalee (4 Jan 2009)

A 0.7 ratio on an MTB ( 18" gear length ) is for climbing stairs.


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## rickangus (5 Jan 2009)

Steve Austin said:


> GBS, your cranks are fine. crank lengths is one of them often debated cycling red herrings. 175 is fine for most cyclists
> simply put:
> shorter cranks are easier to spin
> longer cranks can give more leverage
> ...



I find this comment a little dismissive. 

Crank length is often debated and for cyclists who fall within average dimensions then, yes, 175 will be fine and for those people the topic may, indeed, be a red herring.

However, for those riders who fall outside the normal boundaries, whether tall or short, it is an issue. And the further you fall outside of it the more of an issue it becomes. Of course you can use 175s and live with it, being none the wiser. But why do people spend time and a lot of money perfecting their bike 'fit' or having custom frames built? Because they want to get the greatest possible efficiencies and not taking into account crank length just does not make sense.

For years I used 170 cranks - I never gave it another thought until I tried 175 and found they offered me a noticeable improvement. And now I have much longer ones that even better match my physiology.

I can only repeat my experience of 'fitted' cranks which has been that the benefits are twofold; 

First and foremost, comfort. This is a big one (for me, anyway). Long legs simply don't spin as well as shorter legs. I rode a friend's bike recently with 175s and for me that felt like having to walk with a shorter step than normal, if you see what I mean. Not disastrous, obviously, but certainly a lot less comfortable.

Secondly, I believe there to be an efficiency improvement - although this is difficult to measure. I got my long cranks while recovering from illness so any improvement in performance could be attributed to increasing strength, fitness or mechanical efficiency. However, I did find my cassette ratio was then a bit on the 'low' side and changed it for a taller set.

Perhaps I should say that I am a touring cyclist, not a racer.

GBS, you do appear to have longish legs and it is for you to decide whether this is an area that requires further investigation. My opinion is that you would be better served by those with experience of being outside the 'average' rather than accepting a 'one size fits all' mantra. 

I've attached a couple of links on this matter that make for interesting reading but there are loads of others if you do a google.com search.

I would say, though, that obtaining non std length cranks won't be cheap so you'll need to be sure it's right for you. 

http://www.polaris.net/palmk/Crankset.html

http://www.peterwhitecycles.com/fitting.htm


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## Steve Austin (5 Jan 2009)

You are right my comment is dismissive. dismissive of the confusion your post causes. 

I gave a personal recommendation on the length he needs based on the height he said he is. 
Its not rocket science, and crank length is one of these oft mystified measures on bikes. Its not worth debating the point, but the majority of people would be happy with 170 on roadbikes, and 175 on commuters/tourers/mtbs. it really is as simple as that.


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## rickangus (5 Jan 2009)

You’re right and I agree it’s not rocket science. It’s really very simple - so why you don’t get it I just don’t understand.

Actually, I think I can see where your confusion arises. Crank length is a function of leg length not height.

Happy on std length? I'm sure the majority of people are happy on std length but we're talking about people who are outside of the majority. 

I was happy on std length, too, for a while. But I am much happier now on the correct length cranks.

What's confusing about that?


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## gbs (5 Jan 2009)

to Rick; thank you for passing on yr sources. I will probably look at these tomorrow - heavy work day today. I still have the intuitive view that longer cranks means more leverage and that must help on the steeps. Having said that I think my first priority is to degear ie fit the largest cog possible and reduce the lowest gear ration to something around 1.5x


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## rickangus (5 Jan 2009)

gbs, I think you're right. You do experience an increased leverage with longer cranks - it's a law of physics after all. But there are other implications also that you should be aware of and take into consideration.

In the first instance changing the cassette will be a cheaper and quicker change. Changing cranks for non std length is a much greater financial commitment.


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## Chris James (5 Jan 2009)

rickangus said:


> For years I used 170 cranks - I never gave it another thought until I tried 175 and found they offered me a noticeable improvement.




I have ridden 165mm and 175mm and didn't notice any difference in the crank length, so i find myself agreeing with Steve Austin, albeit that I am 5 foot 11and so presumably within normal design parameters.


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## jack the lad (5 Jan 2009)

gbs said:


> to Rick; thank you for passing on yr sources. I will probably look at these tomorrow - heavy work day today. I still have the intuitive view that longer cranks means more leverage and that must help on the steeps. Having said that I think my first priority is to degear ie fit the largest cog possible and reduce the lowest gear ration to something around 1.5x



Wrong length cranks is probably more of a problem for short people with standard cranks being too long than it is for tall people with them too short.

Even if longer cranks were a benefit uphill they would be a nuisance elsewhere. Bear in mind also that longer cranks mean that at any given speed the pedals describe a bigger circle. Your feet will need to move further for the distance travelled and your legs have to be moved faster to keep up. Your knees will also need to bend through a greater angle at the top of the stroke, putting more strain on your muscles and joints. As you are an old fella, like me, you probably move a bit slower than you used to and appreciate less strain on the knees, not more. I think, on balance, it is better to keep standard cranks but lower your gearing for hills. This is also the implication of the advice given in the second of the two links given. You will, I guess, have 18 or 20 gears to choose from, so you can have low ones for uphills and high ones for down. 

Even at 16 stone and 50 yrs old I could manage White Horse Bank which is 25% on 36/24, 1.5:1. To get up Mt Ventoux I fitted a 34T 'megarange' at the back. That was a mistake as it was too low, but the 24T next lowest was too high. 28T would have been about right. So from my experience I would suggest that on a road bike a compact chainset with a 34 or 36 T front sprocket and a low of 27 or 28 at the back should get you up almost anything the UK can throw at you once you are fit . If you can outpedal 50/11 at the top end you are probably going quite fast enough, thank you. If you can manage with 39/28 that's the cheapest option and the one to try first.

Hope this helps.


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## rickangus (5 Jan 2009)

Completely agree that cranks that are too long can cause discomfort and possible knee problems. Cranks that are too short simply lose comfort and efficiency. Far better to go too short than too long. 

Regarding your point, Jack, about spinning the pedals faster because of the greater pedalling diameter. In my experience (which is what my comments are based on) I don't think I do spin faster, rather I turn more slowly but in a higher gear. I say this because when I am cycling with others at the same speed, I have a lower cadence.

I know my legs don't spin fast - I have a b/c with a cadence counter and I seriously doubt I could get anywhere near 80 rpm (I have other background health issues which don't help).

An analogy in one of the links I posted compares two track athletes running at the same speed, one of them tall, the other short. Although running at the same speed Lanky's legs are turning more slowly compared with Shorty's but with a longer stride, whereas Shorty's legs are spinning faster. We're all built differently and that is how we adjust to meet at a common point.


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## Randochap (5 Jan 2009)

One other disadvantage (perhaps the worst) of longer cranks is the increased danger of pedal strike in corners.

I have short legs, so have recently tried 165s. Don't feel much different to the 170s I've always used.

I've always been a "spinner" and this is probably why knee problems are relatively rare, despite the distances (audax) and climbing I do.

Get longer cranks if leg length dictates, but don't worry about "leverage" on hills; make sure you have the gears you need to spin up them.

Your knees will thank you.


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## asterix (5 Jan 2009)

With a 36 inch inside leg measurement, I suspect I might not be average! Nevertheless, I am unaware of any difference between 170 and 175mm cranks.

WRT the OP, I find that ergonomics and frame stiffness are more important than minor weight differences. The bike built for me by Roberts transformed my hill-climbing abilities. They used 170mm cranks.


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## bleakanddivine (5 Jan 2009)

gbs said:


> Meanwhile having established that the hill in question certainly exceeds my 15% guessestimate and may be close to 20% I will establish another thread to see what views others have of appropriate ratios



The LHCCC (London and Home Counties Cycle Chat) group ride in November took in the main circuit in Richmond Park, some of it in both directions. I don't see anything over 15% in the GPS log.


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## gbs (5 Jan 2009)

to bleakanddivine: I do not argue with mapmyride. Check it out for the section from RHG towards KG. Their data suggests that the short pitch up to the carpark exceeds 20% - I had previously guessed at 15% or so (based on skiing experience - I am an aged but novice biker) . I think the difference in average gradient reading is a function of the length of the measured sector. Regardless of the precise facts of the gradient perhaps you could tell us:
(1) of the gear ratios used by yr mates on that more difficult part of the stretch and (2) let me know how you deal with cleats when you are at yr personal limit.


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## bleakanddivine (6 Jan 2009)

gbs said:


> to bleakanddivine: I do not argue with mapmyride. Check it out for the section from RHG towards KG. Their data suggests that the short pitch up to the carpark exceeds 20% - I had previously guessed at 15% or so (based on skiing experience - I am an aged but novice biker) . I think the difference in average gradient reading is a function of the length of the measured sector. Regardless of the precise facts of the gradient perhaps you could tell us:
> (1) of the gear ratios used by yr mates on that more difficult part of the stretch and (2) let me know how you deal with cleats when you are at yr personal limit.



Hi gbs
Yeah I guess the figures will vary depending on the source. I'm not that familiar with the area myself so we could even be talking about a different stretch!

(1) Don't know what others were using, there was at least one fixed, but I would have used my lowest 36/30. This is the standard equipt on my 1981 tourer. (2) Never used cleats, still have the old toe clips. At 50, I actually prefer sitting rather than pedal dancing, I think it puts less strain on the legs and back, and less disastrous if the chain jumps. I can still get up most things, but the length would eventually take its toll now on anything over say 20%.

Jonathan


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## gbs (6 Jan 2009)

Jonathon, thanks for gear ratio info - makes me feel less embarassed that I failed on 39/23!
BRs GBS


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## gbs (6 Jan 2009)

bleakanddivine said:


> Hi gbs
> Yeah I guess the figures will vary depending on the source. I'm not that familiar with the area myself so we could even be talking about a different stretch!
> 
> (1) Don't know what others were using, there was at least one fixed, but I would have used my lowest 36/30. This is the standard equipt on my 1981 tourer. (2) Never used cleats, still have the old toe clips. At 50, I actually prefer sitting rather than pedal dancing, I think it puts less strain on the legs and back, and less disastrous if the chain jumps. I can still get up most things, but the length would eventually take its toll now on anything over say 20%.
> ...


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## bleakanddivine (6 Jan 2009)

gbs said:


> I doubt that we are confused; travelling from Robin Hood Gate towards Kingston there is only one climb. bikehike.co.uk suggests that the pitch is closer to yr GPS result. BRs GBS



Ah, I wasn't sure whether RH was Robin Hood, Richmond Hill or RoeHampton but I see what you mean. On MapMyRide I played with the distances and got a small stretch of a few yards up the KG end to register as 18-20%, although this is downhill, and I think you are probably referring to the uphill Broomfield Hill section. Both these sections maxed at 14% when I rode them, both ways, Maybe using only the economy mode GPS sampling is why. 

Anyway, good luck in resolving the gearing issue.

Jonathan


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## DreamBig (28 Mar 2012)

Today I came across a nice app called Bike Gear Calculator, www.BikeGearCalculator.com I had the same dilemma to get compact or not. this gear calculator gave me the answers I needed. Switching to compact now. As it turned out there are so many things to take into consideration. http://itunes.apple.com/app/bike-gear-calculator/id505985340?ls=1&mt=8


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