Hobbit712

Greetings to the hive mind of this section.

I was looking for a bike to get my daughters into mountain bike riding. I found a used 2020 Marlin 6 in size small on Facebook market. The previous owner had changed out the stock 2x8 to a 1x8 by only changing the front crank to a Sunrace sealed unit. I am looking to expand the range by possibly changing out the rear cassette to a 10 or 11 tooth. The bike has a short cage Altus derailleur and one bike shop I visited said that would not work. They said I would need a SRAM NX to make it work. They also suggested I change the front sprocket to a 30 or 28 tooth and I might bet some better range with out a lot of difficulty or $$$. Another bike shop suggested a Microshift unit might work but he would have to do some research.

He also changed out the original rear wheel. Are there any other options out there you guys might suggest?

Attached are a few pics in case they are helpful.


Thanks all!

Iride01 

If you are willing to go back to a 2x8 then ask the original owner if they have the original crank and stuff laying around taking up space? That'll be the best way to get more range between high and low gears.

Otherwise, I think you will go from a decent group to a less than decent group to get more range on the rear inexpensively.

travbikeman

Sunrace lists this crankset to be able to work with 10/11/12 speeds: https://www.sunrace.com/en/products/detail/fcmx00

The Shimano FH-M475 can handle up to a 10 speed: https://bike.shimano.com/en-EU/produ...o/FH-M475.html

How much money do you want to put into this bike?

I have been reading and viewing Youtube review video's that the Microshift Advent X system is really good. You can get a new derailleur, shifter and cassette together for a round $130 parts only.

Just an idea.


Edit: Oh yea, add about $20 for a chain. I've seen youtubers that really upgrade or configure the Trek Marlins into a really nice bike. But wow, someone dropped candy into the drivetrain? Pink stuff?

Hobbit712

Iride01 and travbikeman...thank you for the responses

The original owner gave me the old crank but it was supposedly a non sealed unit. The new one is a sealed bottom bracket. I am willing to put a few dollars into it if the girls will be more likely to ride it. I got the bike for $500 so pretty good deal I think.

As for the pink stuff, I had a very old bottle of Rock n Roll red that I put on the chain just before I left on vacation. I bought this bike the day before we left.

GrainBrain

Just a quick bit of math, but going to a 40t max rear cog instead of the current 34t would be a 16% lower gear (like if you used an 11-40 cassette).

If you went with a 28t front ring in place of the 32t, that would lower over all gearing by 13%.

A little more information would be useful, is there specific concerns with the current gearing? You want more range you say, so is your daughter spending most of her time in the lower gears? A 28t ring would be a cheap and easy way to solve that problem.

Going Deore 1x11 would knock you back probably $150 for the cassette, derailleur, chain, shifter. On my hardtail I have the 11-40 cassette as there's not a lot of hills. Just looking now there's a ton of options for 1x, and not a lot of price difference between the Deore and slx or xt. Geeze just saw that Shimano offers an 11-51 cassette for 11 speed!

Iride01 

You paid almost new price for it. So depending on availability in your local area and how desperately you needed something................. well you fill in the rest.

I guess this was something for a gift right? So maybe you also gifted the seller as well as daughters.

GrainBrain

Well he saved about $250 vs walking out of the shop. Not bad.

Hobbit712 I use this website to figure out what I want in drive train gearing.

​​​​​
Edit - huh maybe I should link the site huh? https://www.bikecalc.com/gear_ratios

hokiefyd 

Microshift has some interesting stuff out. Sticking with 8-speed, they have the Acolyte group. You may still need a new chain (longer), but it'd stay 8-speed. They also have the 9-speed Advent and 10-speed Advent X groups. I just ordered some advent parts -- the 11-46 cassette, derailleur, and shifter -- and wish I could give you some first-hand experience. Amazon predicts a 2-3 week delivery window (which is better than what my LBSes were saying: out of stock/backordered).

Sunrace also has a few wide-range 8- and 9-speed cassettes that you can buy independently, but your RD-M310 derailleur very likely won't work with anything larger than the 34-tooth sprocket that's on the bike now (maybe up to 36 teeth)...so you'll need to buy a new derailleur anyway.

Each of those Microshift groups listed above is reviewed pretty favorably by media and riders (just spend an afternoon on a YouTube video binge and you'll see all the info on them).

hokiefyd 

By the way, Hobbit712 , could you please post a picture of the full driver side crank arm? I may need to replace a crankset on one of my bikes and I like the looks of this 96mm BCD one.

Thx!

sweeks

OT: Does it snow in the "God forsaken jungle of SW Florida"?

Hobbit712

It was a gift and was a last minute purchase before leaving on vacation the next morning. New ones if you can find them are $669. With an upgraded crank, new seat, new grips and a slightly upgraded rear wheel I still think I got a good price. Especially in todays market. It was a size small which is was the right size as well.

Thank you @GrainBrain

I was looking at reviews of the AdventX. If I upgrade this one is looking pretty good.




LOL. Only once in my 30+ years here. This was in NC during vacation. We actually had a white Christmas.

This was also part of my upgrade thoughts. Here in FL my daughters may not need the expanded range. But we do vacation in NC a couple time a year where we actually have hills and mountains.