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Gearing for vintage trials ride


Niro
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I'm riding 1970 Montesa Cota 247. I'm beginner and stating to compete in vintage trails events, meaning riding in woods.

My bike has 10/48 sprockets set. 

The Cota manual indicate that the factory bike has 11/46 set. 

The difference is about 12%. But what does it mean? 

My main goal is to ride as slowly as I can in 1st gear and maintain smooth acceleration when needed. 

Does the 11/46 ratio is slower then 10/48? Should I changed back to the factory setting?

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1 hour ago, Bloomfield said:

10/48 is lower gearing so it will accelerate more quickly, but will be slower overall.

Ok. So according to that, is the next assumption true or false:

Bike is on 1st gear and rolling (clutch not pressed, throttle not open) - the bike with the higher gearing (11/46) will roll SLOWER then the bike with the lower gearing (10/48)

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5 hours ago, Niro said:

I'm looking for the slowest gearing while bike in 1st gear and rolling. 

10/48 (4.8:1) is 12% slower than 11/46 (4.2:1).

9 teeth front sprockets are available.

Bigger (custom made) rear sprockets are available.

 

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28 minutes ago, feetupfun said:

10/48 (4.8:1) is 12% slower than 11/46 (4.2:1).

9 teeth front sprockets are available.

Bigger (custom made) rear sprockets are available.

 

So if understand correctly- in order to slower my bike further more, I can change to 9 teeth front sprocket (I prefer to stay with the rear 48T), correct? 

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7 minutes ago, Niro said:

So if understand correctly- in order to slower my bike further more, I can change to 9 teeth front sprocket (I prefer to stay with the rear 48T), correct? 

yes

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2 minutes ago, feetupfun said:

yes

Thanks!

Now I understand this. So a followup question- what are the disadvantages (if any) in going down 1 teeth in the front sprocket? 

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4 hours ago, Niro said:

Thanks!

Now I understand this. So a followup question- what are the disadvantages (if any) in going down 1 teeth in the front sprocket? 

The chain will wear faster.

First gear may be too slow in places when you need a bit of speed and second gear may be too fast for tight stuff. It's risky to change gears in a section so most people have gearing that is the best compromise for their riding style and stay in the one gear.

For many riders, it would be harder to ride smoothly in first gear due to being harder to balance and having reduced acceleration.

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15 hours ago, Niro said:

I'm looking for the slowest gearing while bike in 1st gear and rolling. 

It´s quite a bit slower with 10/48 then 11/46. You can roughly estimate 1 teeth smaller on front sprocket equals 4 teeth larger at rear sprocket.

Try and see if you like it. Use 2nd gear if you need speed. Will also be slower on 2nd gear and all other gears. Perhaps 2nd gear will be more usable

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The sections now are set  quite bit tighter than in 1970. You will find slower is better, especially as when the bike was made you never used the clutch in a section.

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I appreciate all of your enlightening information! 

feetupfun- other than my bike feels faster to my skill level, I really like his behavior in 1st gear. I can pull the bike pretty strong and smooth from almost standing without using the clutch. I also didn't find myself yet need to switch to 2nd gear while in section. Knowing the bike pull strong and that the 1st. gear is very usable gives me confident in sections. 

carl and lineaway- I took trials riding lessons with highly professional and very well known rider and he told me the same, about gates being very tight this days. In my practices at his sections I never used the clutch. But I didn't ride in an event yet. My first event is coming this Sunday. After that I will probably have more knowledge on how sections are set and how I mange to rode my bike. 

Bottom line I think to move 1 teeth smaller in the front sprocket will be a good lesson for me and if I don't like it, I can always go back one teeth up. 

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