Mountain Biking - Road gearing for my Giant

I apologize if this is a repeat question. I found answers pertaining to cassettes, but not cranks.

I'd like to gear up my Giant Rainier by giving it roadie gearing. Replacing the cranks (and cassette, but only if necessary). Having never torn a bike down that far, is it just a matter of adding the road cranks and obtaining a larger chain? I run out of gears going down hills and top out at about 35 mph. Is there an alternative I have overlooked? What is the biggest setup for MTB's? Thanks in advance.

Just buy a new large chainring.

Just buy a new large chainring.

Won't that affect the length my chain must be?

Well, yeah, but you won't need new cranks.

Just buy a new large chainring.

If you go this route make sure your front derailleur is compatible. Most likely you have a 22/32/44 right now. You could possibly go up to a 46 tooth chainring with minimal problems with the front derailleur. Any bigger than that you could run into problems.

I apologize if this is a repeat question. I found answers pertaining to cassettes, but not cranks.

I'd like to gear up my Giant Rainier by giving it roadie gearing. Replacing the cranks (and cassette, but only if necessary). Having never torn a bike down that far, is it just a matter of adding the road cranks and obtaining a larger chain? I run out of gears going down hills and top out at about 35 mph. Is there an alternative I have overlooked? What is the biggest setup for MTB's? Thanks in advance.
What are you running as a cassette now? Also if you're running 35 mph on a MTB on the flats :rolleyes: you should just look at getting a real road bike because there's no way you're pushing that kind of speed on dirt

Back in the day when MTBs were less freeride and more road-like, I used to run a 24-36-48 chainring setup with a old-school 5-bolt crank and regular MTB derailleur. This gave a top gear of 48-12 or 48-11, which was plenty even for slick tire rides. Shifting was a bit slow up to the big ring, and the chain needed to be long enough that it slapped the frame a bit more, but otherwise problems were few.

If you can find a 46 or 48 tooth chainring for the bolt pattern you have now, that would probably be the easiest way to get the on-road speed that you crave. You'll probably need to mess with the front derailleur to get it to work.

The biggest problem you'll encounter with just buying a new big ring is that your front derailleur can handle the spread from your granny gear to your (let's say) 48 tooth chainring. If you ditch the granny then you'll be fine.

However, check with Giant first. You may also encounter problems with a bigger ring rubbing your chainstays. A 48 should have clearence, but if you put road cranks on there with a 52, you'll probably get some conflict, especially from the inside ring.

Not to hijack the thread but I have a similar question. I own a 2004 Kona Shred which came with a bash gaurd in place of the largest chain ring and I have realized that for the type of riding I do I just simply don't need the bash gaurd and since about 75% of my riding is done on the road I would like to add the large ring back on. Anybody have any links to where I can get a decent 42 - 48 tooth ring for a reasonable price? Anything else I should know before adding one?

If your crank needs 4 bolt chain rings also, i dont think there are any beyond 48T.

What are you running as a cassette now? Also if you're running 35 mph on a MTB on the flats :rolleyes: you should just look at getting a real road bike because there's no way you're pushing that kind of speed on dirt

Please read more closely - 35 downhill. I have test-ridden road bikes and am not at all comfortable on them. I like the bigger wheelset and higher gears, but simply cannot sacrifice stability and durability. Even the Cyclocross bikes aren't sturdy enough for my liking. My stock big chanring is is 42t and I'm just wondering if there's a larger 'stock' chanring I can move up to without rebuilding the entire drivetrain. I have a 9-speed cassette that came with it (Giant Rainier). Apologies if I did not specify this is a commuter bike, not a pure dirt bike.

I have test-ridden road bikes and am not at all comfortable on them. I like the bigger wheelset and higher gears, but simply cannot sacrifice stability and durability. Even the Cyclocross bikes aren't sturdy enough for my liking.

sounds to me like the Giant Cyprus series is what you need. but since a new bike might be a bit much you could probably get a larger chainring to fix the problem... You might just want to take it to a shop. Or you could work on spinning since higher cadences are mnore effeicient anyway.

Please read more closely - 35 downhill. I have test-ridden road bikes and am not at all comfortable on them. I like the bigger wheelset and higher gears, but simply cannot sacrifice stability and durability. Even the Cyclocross bikes aren't sturdy enough for my liking. My stock big chanring is is 42t and I'm just wondering if there's a larger 'stock' chanring I can move up to without rebuilding the entire drivetrain. I have a 9-speed cassette that came with it (Giant Rainier). Apologies if I did not specify this is a commuter bike, not a pure dirt bike.

are you bigger than average? becuase road bikes are a lot sturdier than you would think, especially the ones in the 1000 dollar range. there are guys in the road forum that are 225+, and are doing fine w/ their road bikes.

hopwever, its clear that you have a bike now, and are not too eager to replace it. I think your biggest issue would be with chainring clearance. since mountain bikes have fat tires, the chainstays are spread out, interfereing with where big chainrings would go.

Not really (6'1"/220), just used to the geometry, I think. My test rides included some interesting experiences with gravity, running over such insignificant obstacles as small rocks. Didn't take a spill, but came closer than I would have on my Rainier. Maybe it's a case of just biting the bullet and stepping outside the comfort zone, but in the meantime, I'll just shop for a larger mountain chanring.

you ought to be able to replace the small cog on your cassette with an 11 tooth cog. that will help, too.

Check AE Bike. You need to know your bolt circle diameter in order to specify the correct ring. Go with a 46 or 48 ring and you should be fine. If your front derailleur is any less than Deore you will probably have to upgrade it, has to do with the amt. of swing they have...

EDIT: IIRC, the angle of swing on the cheaper fr der.s won't handle the larger diameter of the ring... so not the amt. of swing, but the relationship of the diameter of the ring to where the pivots are located on the der.