Poor man's trials conversion, gearing question

Super Sport · 09-27-2012, 04:22 AM

I have a nice little '74 Yamaha MX175 that I want to set up like a vintage trials bike, just because it's here and paid for. It currently has stock 14/47 sprockets; I don't know the transmission gear ratios. New sprockets are still easy to find and I can get fronts in 12, 13, 14, 15. Rears available in 55, 54 and smaller. Can you suggest a sprocket combo that would be good for playing around my property with small features and steep hills? Then I'm just gonna put on some decent trials tires, rebuild the forks and go have some fun.

lineaway · 09-27-2012, 04:41 AM

I`d go all the way,12-55. Have fun!

Sting32 · 09-27-2012, 06:10 AM

I'd agree with Lineaway, and depending on your property and how you like to ride, I might buy a couple more different gear/size combo's later.

The internal gearing of the bike you have, will be much higher all around, as you probably already know and hopefully wont matter that much since it is for fun

.

FWIW, this is how we got into trials back in 70-71. Dad had his new Suzuki ts-250, stripped down to "motocross" (longer story in other posts) but he rode that bike with small front big rear sprocket for at least a few months, in enduro classes, and I think 1 novice class or 2 rides. I rode a trailhopper (mt-50) when I started, although I was too young to really care about much more than getting to ride what my dad does, I was like 5 or 6.

I still hope to find me one (trailhopper) and fix it up someday, even though my son is 18 already, it isnt a big hurry, lol.

lamotovita · 09-27-2012, 07:21 AM

Yep, all the way on the gearing. Be sure you put a Trials tire on the rear before you put the chain on as you may need to mount the wheel all the way to the rear to allow clearance for the bigger tire (which effectively raises your gearing).

Doctor Zed · 09-27-2012, 12:22 PM

Yeah, What they said.

Get that thing done and I'll bring the Sherco back over for another Trial-a-thon

Super Sport · 09-27-2012, 03:38 PM

All the way it is!

Thanks, guys- I was afraid I could actually gear it too low, but that appears not to be the case.

Super Sport · 09-27-2012, 04:03 PM

Oh... Zed. I don't know if I'll ever be able to hang with you. Took this pic of you last week in my field.

JeffS77 · 09-27-2012, 08:05 PM

Quote:

Originally Posted by Super Sport

All the way it is!

Thanks, guys- I was afraid I could actually gear it too low, but that appears not to be the case.

Dude if you lived closer I would trade you my TLR200 for it

09-27-2012, 04:22 AM	#1
Super Sport ^OP Adventurer Joined: Feb 2010 Location: Baraboo Bluffs, WI Oddometer: 79	Poor man's trials conversion, gearing question I have a nice little '74 Yamaha MX175 that I want to set up like a vintage trials bike, just because it's here and paid for. It currently has stock 14/47 sprockets; I don't know the transmission gear ratios. New sprockets are still easy to find and I can get fronts in 12, 13, 14, 15. Rears available in 55, 54 and smaller. Can you suggest a sprocket combo that would be good for playing around my property with small features and steep hills? Then I'm just gonna put on some decent trials tires, rebuild the forks and go have some fun. __________________ If it ain't broke, fix it 'til it is.

09-27-2012, 07:21 AM	#4
lamotovita Studly Adventurer Joined: Oct 2007 Location: WA USA Oddometer: 862	Yep, all the way on the gearing. Be sure you put a Trials tire on the rear before you put the chain on as you may need to mount the wheel all the way to the rear to allow clearance for the bigger tire (which effectively raises your gearing). __________________ It's not a big motorcycle, just a groovy little motor bike.

09-27-2012, 03:38 PM	#6
Super Sport ^OP Adventurer Joined: Feb 2010 Location: Baraboo Bluffs, WI Oddometer: 79	All the way it is! Thanks, guys- I was afraid I could actually gear it too low, but that appears not to be the case. __________________ If it ain't broke, fix it 'til it is.

09-27-2012, 04:03 PM	#7
Super Sport ^OP Adventurer Joined: Feb 2010 Location: Baraboo Bluffs, WI Oddometer: 79	Oh... Zed. I don't know if I'll ever be able to hang with you. Took this pic of you last week in my field. __________________ If it ain't broke, fix it 'til it is.

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09-27-2012, 04:41 AM	#2
lineaway Studly Adventurer Joined: Oct 2011 Location: nm Oddometer: 760	I`d go all the way,12-55. Have fun!

09-27-2012, 06:10 AM	#3
Sting32 Trails Evangelist Joined: Oct 2009 Location: Minneapolis, Ks Oddometer: 963	I'd agree with Lineaway, and depending on your property and how you like to ride, I might buy a couple more different gear/size combo's later. The internal gearing of the bike you have, will be much higher all around, as you probably already know and hopefully wont matter that much since it is for fun . FWIW, this is how we got into trials back in 70-71. Dad had his new Suzuki ts-250, stripped down to "motocross" (longer story in other posts) but he rode that bike with small front big rear sprocket for at least a few months, in enduro classes, and I think 1 novice class or 2 rides. I rode a trailhopper (mt-50) when I started, although I was too young to really care about much more than getting to ride what my dad does, I was like 5 or 6. I still hope to find me one (trailhopper) and fix it up someday, even though my son is 18 already, it isnt a big hurry, lol.

09-27-2012, 12:22 PM	#5
Doctor Zed Resident Joined: Mar 2009 Location: Lake Mills, Wi Oddometer: 857	Yeah, What they said. Get that thing done and I'll bring the Sherco back over for another Trial-a-thon