Gearing issues

[cabbieman]

Asking for a friend as we're both newbies and not sure. My friends bike has a crank 52-39. It's an 8 speed. He's having problems going up hills. Is it the lack of gears he has (16 in total)? Can he change the front crank or is it better to change the cassette to a 10 speed or similar? Is it that easy or would he have to purchase a new bike?

 

[ianrauk]

He can buy and fit what is called a compact crank set which is usually 50-34. That would make things easier.
10 speed cassette would be no good as he would have to change the shifters too.

 

[Spiderweb]

I have a 52/39 crank on my daily rider/commuter, I changed the rear cassette from a 12/25t to a 12/30t. You may need a new longer chain but the rear derailleur should be fine. I find the larger 30t rear sprocket much easier on the hills and it was the cheapest option.

 

[nickyboy]

If he's having problems getting up hills and he can't wait to get fitter or lighter or fitter and lighter he needs an easier gear

You need to focus on the small number on the crank (in this case 39) and the biggest number of teeth on the sprocket (this might be 25, 27, 28 etc). To make an easier gear you can make the small number on the crank smaller or the biggest number of teeth on the sprocket bigger. They have the same effect. You can do both if you like

Obviously there are cost implications as your friend will have to buy either a new crank or a new sprocket. I would go to a bike shop and ask them which would work out cheaper. As others have said, as soon as you start trying to fit, say, a 10 gear sprocket onto a bike which previously had an 8 gear sprocket, there are knock on problems which further add to the cost so it isn't something that we can give a definitive answer to

 

[mjr]

In addition to what @nickyboy writes, he also needs to make sure he's actually shifting into the appropriate gear - and a few shift levers seem to be numbered 1=high rather than 1=low, so look at the back to make sure: small cog at the front, big at the back.

That's assuming that "problems going up hills" means struggling to get up them at all. If you mean struggling to get up them as fast as you, it is possible that if you've got 10 at the back and he's got 8 then you're more likely to get the best possible gear for any given hill than he is... but like others said, changing that's really not an easy fix... and I'd expect the difference between 8 and 10 not to be noticeable for newbies, unlike when I ride my 3-speed with friends with 20+ speeds and spend all day yoyoing around the group

 

[boydj]

The cheapest and easiest change would be to fit a cassette with a wider range - 8 speed, say 12-32, can be had for under a tenner. Changing cranks is much more expensive and there's not much relief to be gained from a smaller chainring, because, as I understand 38 is as low as you can go on these old cranksets.

 

[drlk]

My friends bike has a crank 52-39. It's an 8 speed. .... Can he change the front crank or is it better to change the cassette to a 10 speed ...

First, you need to understand the difference between crank, chainwheel, cassette and ratios. After you have learned the differences, perhaps you could re-phrase your questions and receive more useful answers. At the moment, you're confused and the right decision will make a big difference to your riding. No offence intended.

 

[cabbieman]

First, you need to understand the difference between crank, chainwheel, cassette and ratios. After you have learned the differences, perhaps you could re-phrase your questions and receive more useful answers. At the moment, you're confused and the right decision will make a big difference to your riding. No offence intended.

Thanks for that. Yes as a newbie it is a bit confusing as to what goes where and what influences something else. The answers to the question though have provided some direction to take. It's the only way to learn. Feet 1st. No offence taken. Thankyou for taking the time to respond

 

[nickyboy]

First, you need to understand the difference between crank, chainwheel, cassette and ratios. After you have learned the differences, perhaps you could re-phrase your questions and receive more useful answers. At the moment, you're confused and the right decision will make a big difference to your riding. No offence intended.

Come on. It wasn't that hard to understand the question. Let's try not to be deliberately obtuse on the Beginners forum

 

[MichaelW2]

Your friend who has difficulty on hills should change the range of his gearing so the lowest gear is lower. You would also lower the top gear but that doesn't matter.
You lower the gear by reducing the size of a front chainring or increasing the size of a rear sprocket.
You don't need to alter the number of sprockets, 8 speed is fine. The current 8 speed rear derailleur may cope with a larger sprocket, but may not so could need a different one.
The current crank set ( also called chain set) is reaching the limit for smallest chainring size, so it is easier to start by replacing the rear cassette with larger sprockets. If this is not low enough you can change the chainset to one with smaller diameter holes to take a 34/50 ring combination. This is fairly common and called a compact chainset.

 

[Dogtrousers]

A new cassette (32T big sprocket) and chain would be an easy first step.

Even if the rear derailleur can't cope with the increased range, a replacement that can will only cost £20 or so.

For a more benefit, but more effort, new 50/34 chainset could be quite a bit of faff to fit and may possibly also need a new front derailleur. And while you're at it changing or servicing the bottom bracket bearings would probably be a good idea.

Go for it. Low gears rock.

 

[drlk]

Thankyou for taking the time to respond

You're welcome. A good starting point is to know your gears. Count the teeth on all the 8 sprockets and the teeth on the two chainrings, assuming you have 2 at the front, which will be 42/52 with an 8 speed cassette. Then use a spreadsheet to do divisions > 42/23, 42/21,.. etc for all the gears. You should aim for about 1.83 on your lowest gear and buy a cassette with the closest spread, like 13-23 Shimano CS-HG50. This is for road use, and at your early stage of fitness, you don't need to worry about changing to different size chainrings.
New components should always be a bought as a set of chain, cassette and chainrings. Anything else is a false economy as the worn components will not fit the new chain.

 

[Spiderweb]

You're welcome. A good starting point is to know your gears. Count the teeth on all the 8 sprockets and the teeth on the two chainrings, assuming you have 2 at the front, which will be 42/52 with an 8 speed cassette. Then use a spreadsheet to do divisions > 42/23, 42/21,.. etc for all the gears. You should aim for about 1.83 on your lowest gear and buy a cassette with the closest spread, like 13-23 Shimano CS-HG50. This is for road use, and at your early stage of fitness, you don't need to worry about changing to different size chainrings.
New components should always be a bought as a set of chain, cassette and chainrings. Anything else is a false economy as the worn components will not fit the new chain.

So every time you change the chain you renew the cassette and the front chainrings??
That is completely false economy!
Roughly speaking one cassette should last the life of 3 chains and the front chainrings should last even longer.

 

[nickyboy]

You're welcome. A good starting point is to know your gears. Count the teeth on all the 8 sprockets and the teeth on the two chainrings, assuming you have 2 at the front, which will be 42/52 with an 8 speed cassette. Then use a spreadsheet to do divisions > 42/23, 42/21,.. etc for all the gears. You should aim for about 1.83 on your lowest gear and buy a cassette with the closest spread, like 13-23 Shimano CS-HG50. This is for road use, and at your early stage of fitness, you don't need to worry about changing to different size chainrings.
New components should always be a bought as a set of chain, cassette and chainrings. Anything else is a false economy as the worn components will not fit the new chain.

@drlk please read the OP. His mate has 52/39 front. Your idea that there should be a maximum gear ratio of 1.83 is beyond crazy. That gearing would be useless for hills. To give an idea I'm reasonably fit and run a smallest gear of 34/27 which is 1.26

And don't get me started on your suggestion of changing the chain, cassette and chainrings. Cassettes should last about 3 chains or so. I've no idea how long chainrings (that's the 52/39 bits OP) last but I'm still on my originals after 25,000km and about 7 chains

 

[Dogtrousers]

You should aim for about 1.83 on your lowest gear and buy a cassette with the closest spread, like 13-23 Shimano CS-HG50.

I have to say that I feel is very not terribly good advice for someone who is looking to lower their bottom gear. What's needed is the widest spread. 30 or 32T for the biggest sprocket.

For reference a 34/32 is 28" or about 1.06 Touring bikes sometimes have "stump puller" gears that are in the low 20"s but you'd need a triple for that.

Narrow spreads are for people who are incredibly fussy about their gears and also are either uber fit or live in a very flat place.