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?
gear ratios and hill climbs
- Thread starter gbs
- Start date
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RedBike
New Member
- Location
- Beside the road
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
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
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.
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.
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.
I aint got the foggyest what that means.
Sorry if im I right one.
butki55.
RedBike
New Member
- Location
- Beside the road
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.
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.
E
Euan Uzami
Guest
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.
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.
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!
E
Euan Uzami
Guest
gbs said:
15%, you are standing up out of the seat (honking) i presume? you get a lot more torque through the cranks that way.
>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!
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!
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!
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!
E
Euan Uzami
Guest
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.
rickangus
Über Member
- Location
- west sussex
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.
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.
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
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
Steve Austin
The Marmalade Kid
- Location
- Mlehworld
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.
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.
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.
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.
