[FiveThreeOh]

Being that I never ever use my front derailleur, I'm considering going to a 1x7. Totally aware of the simple solution of continuing to not use the front derailleur and leaving it as is. That said, I like the clean look of a 1x and the idea having a cleaner cockpit.

My current chain rings are not modular, so I can't simply take off the first and third ring. Id also like to take the opportunity to get rid of my chrome cranks and get some black ones.

Wondering if I can simply purchase a new crankset and chain ring. How will my chain angle be affected? Could I shorten my chain due to the reduction in gears?

This is planned for a trek marlin 5. Being that it's an entry level bike, I don't want to spend a fortune on parts.

I know some are going to recommend saving my money and getting a newer/better bike. Perhaps that'll happen down the road, but right now I'm just looking to fill my time with fun, reasonably affordable tasks that'll scratch my tinkering itch while I'm down. (currently not able to ride due to injury)

 

[J.B. Weld]

Sure, why not? I'd look for something like a Deore crankset that comes with a bb and a N/W chainring that's the right bcd.

You can shorten your chain to fit but if it has much use at all I'd consider replacing it, of course that could potentially mean a new cassette too

Also consider leaving the front derailleur on for a chainguide, without a clutch derailleur you might get chain drops now and then without it.

 

[FiveThreeOh]

Sure, why not? I'd look for something like a Deore crankset that comes with a bb and a N/W chainring that's the right bcd.

You can shorten your chain to fit but if it has much use at all I'd consider replacing it, of course that could potentially mean a new cassette too

Also consider leaving the front derailleur on for a chainguide, without a clutch derailleur you might get chain drops now and then without it.

Gunna really show my noobness here but what is BDC?

I've also considered replacing my freewheel. I don't know enough about freewheels or cassettes yet to make a wise/worthy decision. That's not to say i haven't looked around. Ive seen seven speeds with a "mega range" gear? Seen different teeth numbers. Don't really know what all that means yet or what I could gain.

Regarding the derailleur-chain guide idea, I would definitely be getting a purpose built chain guide. It another opportunity for me to rid the bike of any chrome parts. You're right tho I'm definitely gunna need something to keep that chain on.

 

[J.B. Weld]

BCD is bolt circle diameter, you need to get a chainring with one that matches the one on your crankset.

I wouldn't worry about changing the freewheel (or cassette) unless it's worn, options are pretty limited for 7-speed anyway.

 

[TwiceHorn]

BDC is actually BCD, Bolt Circle Diameter. A crank has a "spider" with threaded holes to receive bolts that hold the chainring on. That spider, or the holes in it, describe a circle having a diameter. It is the "size," other than the number of teeth, of a chainring.

Freewheel vs. free hub is described here. https://sheldonbrown.com/free-k7.html

Basically, a freewheel includes the ratchet mechanism in the sprockets, instead of the hub. You can't use a "cassette," properly termed, on a freewheel. There's a more limited selection of sprocket clusters compared to cassettes.

The number of teeth on a cog in a cassette or on a chainring basically correspond to the "gear ratio" of the bike. By going from 3x to 1x with the same rear cogs, you are giving up roughly 2/3 of your gear range (roughly because there is inevitably overlap in the 21 gears, making them effectively 18 or 19 gears, not to mention cross-chaining). Here is an actual gear-ratio calculator https://www.sheldonbrown.com/gear-calc.html

The Sheldon Brown website is a good one-stop shop for bike knowledge.

Most people initially go by the chainring size, in teeth, and the largest and smallest sprockets on a cassette or rear gear cluster to get a notion of the gear range of a bike. The intermediate cogs can be important too, as some want more low gears, some more high. This is why you hear people with 1x talking about their front ring, 28, 30, 32, 34 tooth, with 30 and 32 being common, and cassettes being 11-46 or 50 or 10-46 or 50, with 46 being indicative of 1x11, and 50 being indicative of 1x12, typically.

So, you will need cranks with a spider so you can mount the (narrow wide) chainring of choice (same as your middle ring?). A bottom bracket that will fit your shell as well as your new cranks. You might could get away with a 2x set and put a bashguard on the big spider. A chain guide, and a new chain, probably shorter than your old one. If you do other than a 3x, square taper crank, you are probably going to have to fiddle with spacers to keep your chainline right.

It's not insurmountable, but it's a lot of fiddling and probably a couple hundred bucks, which is why people give you the advice you don't like.

 

[FiveThreeOh]

BDC is actually BCD, Bolt Circle Diameter. A crank has a "spider" with threaded holes to receive bolts that hold the chainring on. That spider, or the holes in it, describe a circle having a diameter. It is the "size," other than the number of teeth, of a chainring.

Freewheel vs. free hub is described here. https://sheldonbrown.com/free-k7.html

Basically, a freewheel includes the ratchet mechanism in the sprockets, instead of the hub. You can't use a "cassette," properly termed, on a freewheel. There's a more limited selection of sprocket clusters compared to cassettes.

The number of teeth on a cog in a cassette or on a chainring basically correspond to the "gear ratio" of the bike. By going from 3x to 1x with the same rear cogs, you are giving up roughly 2/3 of your gear range (roughly because there is inevitably overlap in the 21 gears, making them effectively 18 or 19 gears, not to mention cross-chaining). Here is an actual gear-ratio calculator https://www.sheldonbrown.com/gear-calc.html

The Sheldon Brown website is a good one-stop shop for bike knowledge.

Most people initially go by the chainring size, in teeth, and the largest and smallest sprockets on a cassette or rear gear cluster to get a notion of the gear range of a bike. The intermediate cogs can be important too, as some want more low gears, some more high. This is why you hear people with 1x talking about their front ring, 28, 30, 32, 34 tooth, with 30 and 32 being common, and cassettes being 11-46 or 50 or 10-46 or 50, with 46 being indicative of 1x11, and 50 being indicative of 1x12, typically.

So, you will need cranks with a spider so you can mount the (narrow wide) chainring of choice (same as your middle ring?). A bottom bracket that will fit your shell as well as your new cranks. You might could get away with a 2x set and put a bashguard on the big spider. A chain guide, and a new chain, probably shorter than your old one. If you do other than a 3x, square taper crank, you are probably going to have to fiddle with spacers to keep your chainline right.

It's not insurmountable, but it's a lot of fiddling and probably a couple hundred bucks, which is why people give you the advice you don't like.

I appreciate the advice. Lots of info there.

It's not that I don't like the new bike advice. I understand it. And I might get a newer bike one day. But right now I'm content with learning and get better on my entry level bike. Part of that fun is the enjoyment I get from researching, upgrade projects, and customization, especially right now while I've got a cast on.

 

[J_Westy]

Sure, why not? I'd look for something like a Deore crankset that comes with a bb and a N/W chainring that's the right bcd.

Agreed. Deore is a decent pricepoint. FC M617 for example.

Not sure what size you are, but if you're on a Medium or Small frame, you could consider shorter crankarms too. There's a million experts on this topic, but I keep it simple:
L = 175mm
M = 170mm
S = 165mm

Unfortunately, this would also be a component that you might not be able to move to a new bike someday since it would likely have "boost" spacing.

 

[Harold]

Being that I never ever use my front derailleur, I'm considering going to a 1x7. Totally aware of the simple solution of continuing to not use the front derailleur and leaving it as is. That said, I like the clean look of a 1x and the idea having a cleaner cockpit.

My current chain rings are not modular, so I can't simply take off the first and third ring. Id also like to take the opportunity to get rid of my chrome cranks and get some black ones.

Wondering if I can simply purchase a new crankset and chain ring. How will my chain angle be affected? Could I shorten my chain due to the reduction in gears?

This is planned for a trek marlin 5. Being that it's an entry level bike, I don't want to spend a fortune on parts.

I know some are going to recommend saving my money and getting a newer/better bike. Perhaps that'll happen down the road, but right now I'm just looking to fill my time with fun, reasonably affordable tasks that'll scratch my tinkering itch while I'm down. (currently not able to ride due to injury)

My suggestion is just to ride it. With the limited amount of riding you've been able to do, I have a feeling you just haven't found a spot where you'd use your other chainrings, particularly the small one. The big ring, I could envision never needing, but considering what you have, I don't think it's worth changing anything right now. Limiting yourself to a single chainring on a 7spd freewheel is going to set you up for pretty limited gearing range and there's a good chance if you just ride more (and more places), you're going to find yourself wishing you had more eventually.

 

[TwiceHorn]

Harold, as usual, raises an excellent point. It's not uncommon for riders to rarely come out of the middle ring, but usually on 3x9 or 10. It's also extremely common for newbs not to shift enough.

 

[GiddyHitch]

Well, I learned something new today - bikes can still come with 3x7 drivetrains in 2019! Both ends of that are surprising to me!

Deore cranks are great for the money but you'll still need to buy a chainring and chainring bolts if it's not a 1x, not to mention that if you have a 14-28 cassette like the current Marlin, you're not going to be having much fun on any rides with elevation gain.

 

[Wheelspeed]

Are you mostly a road-biker? They have a reputation of judging components. Mt bikers more often think rocking old stuff is cool. I have a '19 1x12 in the shop so took out my ~'97 with 3x7 and had a great time on it in our local public group ride.

I never once used the big chainring because I guess I'm not a strong enough rider but whatever. We all had a good time.
Here's the 3x7...