Newbie question on gears

Dartmoorcf

Regular
Hi there
I've got a hybrid Marin bike (san rafael ds1) and I've been cycling round the hills of Dartmoor. The bike is pretty heavy at14.9kg but it does the job.
A friend has lent me a much lighter bike a Trek alpha 2.5) which has much thinner tyres 25mm rather than 40mm.
It is much faster on the straights and downhills and is a lovely bike. The pot holes and rubbish roads round here are not as forgiving ride-wise as the Marin due to the lack of suspension and thinner tyres.
On steep hills I find the hybrid is actually easier. It seems to have much lower gears meaning I can get up most of the really horrid hills whereas the Trek in its lowest gear is a struggle to keep moving.

Ideally I'd like a bike with wider tyres but retains the lightness of the Trek bike with the added feature of handling a few tracks and trails. I was looking at the Specialized Diverge E5 base which looks good. However would it have the same "higher" gearing as the Trek or does anyone know if the lowest gear is likely to be ok for steep climbs.

I asked in the bike shop and their answer was 'the road bike isn't as good on hills" but didn't really explain why. Maybe it is because the Marin has 3 cogs and 21 gears whereas the Trek only has 2 cogs of 9.

Thanks
 

CanucksTraveller

Macho Business Donkey Wrestler
Location
Hertfordshire
It's not a question of how many gears or "cogs" a bike has when you're working out how easily it'll go up hills.
It's how many teeth there are (a) on the rear cassette (where more teeth and a larger cog means easier pedalling), and (b) how few teeth the smallest ring at the front has (where less teeth or a smaller ring means easier pedalling).

You can, if you're that way inclined have all sorts of fun (!) working out gear ratios, and perverts with slide rules and brown dust coats will happily help you learn about something called gear inches, but in practice it holds true that most hybrids, MTBs, and those "adventure" bikes will all have lower gearing (bigger cogs) available at the bottom end.
So what the guys in your bike shop should have said, if they were being more helpful, is that road bikes tend to be more optimised towards faster top end speeds, and a hybrid will trade some of the faster cogs for some bigger ones, for to go up hills more easy.
 
What constitutes a "steep" climb and what constitutes "OK" gearing are both personal opinion rather than matters of fact, and depend hugely on fitness.

If you go for a bike with wider tyres they will add weight and make the bike feel less sporty. Again, whether that matters is subjective rather than objective; but there is a balance between ability to ride on rough surfaces comfortably, and speed on smooth surfaces. Once you get to the point of accommodating knobbly tyres to be able to ride on offroad tracks comfortably and with sufficient grip, you'll make a huge difference to the effort you need on smooth tarmac. You really can't have both.

For the specific question on gearing, what matters is the ratio (smallest front cog)/(largest back cog), in teeth numbers. You can look it up on the spec, or just count. On specs, the front cog will be referred to as "chainset" or "chain wheel" and the rear as "cassette", each given with a range of smallest to largest.

Compare that for your current bike and the two you're considering will give you your answer.
 
OP
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Dartmoorcf

Regular
Hiya. Thanks. That's very helpful.

Here are the details...
The Marin is
Crankset Shimano FC-TY301, 48/38/28T
And cassette is SunRace 7-Speed, 11-34T

The current Trek (on loan)
Shimano Compact 50/34
Shimano 105 11-28, 10 speed

And the Specialized says
Shimano Claris R200
Sunrace, 8-speed, 11-34t

I'm not looking for chunky tyres just wider than the 25s on the loan bike. I cant fit wider as no clearance apparently.
Also good puncture protection.

As for hills. The roads here are where they do the Dartmoor Demon and Devil bike rides. One of the downsides of living 1200ft up!
Thanks
 
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Dogtrousers

Kilometre nibbler
A little bit of research suggests that off the peg the Marin has three chainrings 48/38/28 (number of teeth) and a cassette with the range of 11-34 (smallest sprocket-largest sprocket)

A bit more unreliable research suggests that the Trek was originally supplied with a double chainset of 50/34 and a cassette of 11-27 teeth. Of course the owner may have fitted different stuff on it, but we'll assume that it has this.

The both have the same sized wheels "700C" which means that the rim size is 622mm (don't ask).

Because they have the same sized wheels it means we can compare the gearing directly. If one had different sized wheels to the other it would be more complicated. The fatter tyres on the Marin may affect things a bit, but we can ignore that.

So the Marin has a bottom gear of 28/34 (chainring/cassette) and the Trek has 34/27. That's a really significant difference. The Marin has a much lower bottom gear, making it easier (but slower) to go up steep hills.

Some back of a fag packet calculations suggest that for one complete turn of the pedals the Marin will go forward a bit over 2m. But the Trek will go forward about 2.8m. That means in each pedal rev you have to put in a load of extra work, so the pedals are stiffer and it's harder to do.

So when looking at new bikes a key question is "how low is the bottom gear". If the smallest chainring is smaller than the biggest sprocket (as is the case with 28/34) the answer is "really low". If it's the same (as is the case with my bike, 34/34) the answer is "low". But by the time you get to the Trek's 34/27 the answer is "not very low at all".

Many road bikes on the market these days go down to 34 chainring with 32 or 34 at the back. That's not as low as your Marin. It may be OK for you. I don't know, you'd need to try it.

You also say you're looking for fatter tyres than the Trek's 25s. This means you need to ask "what is the largest tyre clearance".

Road bikes with low gears and clearance for big tyres (and some other features) are currently being marketed as "gravel" bikes. Many people on here hate that term, and its very mention causes angry paragraphs to be posted about marketing fads etc. But it is useful - if something is described as "gravel" it may well have what you're looking for (low bottom gear, big tyre clearance). If you're looking for a new bike, that is.
 
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OP
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Dartmoorcf

Regular
A little bit of research suggests that off the peg the Marin has three chainrings 48/38/28 (number of teeth) and a cassette with the range of 11-34 (smallest sprocket-largest sprocket)

A bit more unreliable research suggests that the Trek was originally supplied with a double chainset of 50/34 and a cassette of 11-27 teeth. Of course the owner may have fitted different stuff on it, but we'll assume that it has this.

The both have the same sized wheels "700C" which means that the rim size is 622mm (don't ask).

Because they have the same sized wheels it means we can compare the gearing directly. If one had different sized wheels to the other it would be more complicated. The fatter tyres on the Marin may affect things a bit, but we can ignore that.

So the Marin has a bottom gear of 28/34 (chainring/cassette) and the Trek has 34/27. That's a really significant difference. The Marin has a much lower bottom gear, making it easier (but slower) to go up steep hills.

Some back of a fag packet calculations suggest that for one complete turn of the pedals the Marin will go forward a bit over 2m. But the Trek will go forward about 2.8m. That means in each pedal rev you have to put in a load of extra work, so the pedals are stiffer and it's harder to do.

So when looking at new bikes a key question is "how low is the bottom gear". If the smallest chainring is smaller than the biggest sprocket (as is the case with 28/34) the answer is "really low". If it's the same (as is the case with my bike, 34/34) the answer is "low". But by the time you get to the Trek 34/27 the answer is "not very low at all".

Many road bikes on the market these days go down to 34 chainring with 32 or 34 at the back. That's not as low as your Marin. It may be OK for you. I don't know, you'd need to try it.

You also say you're looking for fatter tyres than the Trek's 25s. This means you need to ask "what is the largest tyre clearance".

Road bikes with low gears and clearance for big tyres (and some other features) are currently being marketed as "gravel" bikes. Many people on here hate that term, and its very mention causes angry paragraphs to be posted about marketing fads etc. But it is useful as if something is described as "gravel" it may well have what you're looking for (low bottom gear, big tyre clearance). If you're looking for a new bike, that is.
Thanks very much. This is most useful info. The Trek is on loan and will go back soon. I guess now is a bad time to buy any bike. Our local dealer has zero bikes in my size (xl) from any manufacturer!
 

MichaelW2

Veteran
The easiest way of comparing gear ratios on different bikes is to use a measure such as "gear inches". You can achieve the same gear inches or gear ratio using different front/rear cog combinations.
Do it all roadbikes often marketed as gravel or cyclo cross or adventure or touring are a very useful style. The tyre clearance may max out at 32mm on some, which is OK for rough roads and farm tracks but a bit wider is always useful. Mudguards reduce your max tyre clearance by 3-5 mm of the designated tyre size eg 37mm to 32mm.
 
Alright, R200 has a 34T inner ring.

so the three bikes are pretty much evenly split on their lowest gear - the specialised is exactly half way between the other two in terms of ratios. It has 35mm tyres to start with and you can fit up to 47, so much larger than the 25s on the trek.

Whether the gearing is low enough, only you can say!
 
OP
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Dartmoorcf

Regular
Ok so looking at a different bike
A Cannondale CAADX1
This has the chainset below. Would I be right in thinking this might be a better option?
Chainset:FSA Omega ME Alloy, 46/30
 
Ok so looking at a different bike
A Cannondale CAADX1
This has the chainset below. Would I be right in thinking this might be a better option?
Chainset:FSA Omega ME Alloy, 46/30
It depends what you want!

If you want a lower bottom gear, you need to look at the cassette as well as the chainset. Just calculate the ratio front to rear, as posted above
 

Dan77

Active Member
Location
Worcester
I have a hybrid with 48/38/28 at the crank and an 11/32 cassette. This gives me a bottom gear of 28/32.

I have been actively trying to avoid using that bottom gear on the front though because it just feels like a cop out and I like to punish myself. I did my most climbing so far in a ride this weekend (only 600m total) and didn’t use it at all.

I plan to get an endurance road bike with 34/34 bottom gear. Whilst it’s not as low as the 28/32, it’ll be a lot lower than I’m currently allowing myself to use. Combined with the reduced weight, thinner tyres and better aerodynamics I should be able to get up hills quicker. How much quicker remains to be seen.

I think the 34/34 is pretty low gearing and should be enough for most people. I’m not trying to ride around the Dartmoor Hills though and don’t know how steep they are. Also depends how fit you are and how much power you generally push out. The difference between a 34 and the 28 on your Trek loan bike is significant though.
 
OP
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Dartmoorcf

Regular
I have a hybrid with 48/38/28 at the crank and an 11/32 cassette. This gives me a bottom gear of 28/32.

I have been actively trying to avoid using that bottom gear on the front though because it just feels like a cop out and I like to punish myself. I did my most climbing so far in a ride this weekend (only 600m total) and didn’t use it at all.

I plan to get an endurance road bike with 34/34 bottom gear. Whilst it’s not as low as the 28/32, it’ll be a lot lower than I’m currently allowing myself to use. Combined with the reduced weight, thinner tyres and better aerodynamics I should be able to get up hills quicker. How much quicker remains to be seen.

I think the 34/34 is pretty low gearing and should be enough for most people. I’m not trying to ride around the Dartmoor Hills though and don’t know how steep they are. Also depends how fit you are and how much power you generally push out. The difference between a 34 and the 28 on your Trek loan bike is significant though.
Getting fitter by the day. Lost 20kg now with another 5 to go. The cycling is really helping.
 
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