How to gear it

[GregMember]

Mr Blue wrote:

Quote:

T/B is indeed correct about torque values on front sprocket size.

We did the same with the kids on BMX bikes, long crankarms as practical for little legs, and as small a front sprocket and compensate with the rear to retain the optimal gearing… a very switched on bloke showed me this years ago.

But as also stated small front sprockets wear chains faster.

Exactly Bruce, thats a great example

One other important thing no two bikes are the same or ridden the same. Even same models, riding styles one has a pipe or jetting kit or both, one guy revs a bike more or rides a gear higher.

Chops Banana was such a pig of a bike until we geared it up (smaller rear) The DR engine is a torquey engine and has a stronger mid range then top end thus the gearing change opened the broad power in the middle of the rev range up. It still climbed everything and was better it the tight going of the pine forests in Orange, 2nd gear instead of 2nd, 3rd, 2nd, 3rd easier to ride. I was lucky to do 1000 odd kays on it

Good luck Boony working it out and learning for yourself is most of the fun IMO

TB

[glennMember]

Mmmmmmmm seems confusion reins around here at the moment.

1.I know what gearing suits me in what terrain.

2. My question was should you change the rear or the front sprocket to gain the required gearing.

My DRZ feels absolutley sweet for me running a 14 front and a 50 rear.
yes I do gear down for extended rides in tight trails and go back to standard for long open rides like an adventure ride.but for general rides like on the weekend it 14/50 for me on my bike for my riding style.

I will be changing the rear sprocket as of now when the gearing neads changing purely for wear reasons.

Cheers

Boony

[GregMember]

Boony will a 15 fit on the front of a DR? The reason I ask is because as you know a front wears faster then a rear, normally two fronts to a rear (three or more with quailty rear sprockets)

TB

[glennMember]

Dont think so with the case saver in place :dry:

[scott bockingMember]

Mr Blue wrote:

Quote:

T/B is indeed correct about torque values on front sprocket size.

We did the same with the kids on BMX bikes, long crankarms as practical for little legs, and as small a front sprocket and compensate with the rear to retain the optimal gearing… a very switched on bloke showed me this years ago.

But as also stated small front sprockets wear chains faster.

Back in the day BMX bikes ran 44/16 but today the standard is 25/9. Similar ratio but in keeping with what Mr Blue was trying to achieve back in the day.

STM

[Steve WyethMember]

Why toque multiplication was even mentioned is beyond me. We are supposed to be giving advice to a average Joe (no offense Boonster) dirt bike rider. Like a lot of other threads someone has asked what is a relatively simple question and has been provided with wild answers.

Torque multiplication matters on a BMX because the 45Kg boy riding it puts out about 0.2 horespower and needs every single mechanical advantage he can muster. This can be considered an ‘extreme’ end of the scale where a small mechanical advantage can make a noticeable difference. At the other end, drag cars, high powered engine etc. it is also noticeable as the they measure performance down to 1000th’s of a second.

Let’s be honest, torque multiplication makes f’ all difference on dirt bike when changing from a 13,14 or 15 tooth front sprocket.

If you are going to worry about that there are heaps on other things like, fairing drag coefficients, tyre pressure, bike weight, rider weight and heaps of other factors that can be looked at and have a more noticeable effect on performance.

Remember we are giving advice to dirt bike riders, not moto GP riders.

[GregMember]

moto wrote:

Quote:

Why toque multiplication was even mentioned is beyond me. We are supposed to be giving advice to a average Joe (no offense Boonster) dirt bike rider. Like a lot of other threads someone has asked what is a relatively simple question and has been provided with wild answers.

Torque multiplication matters on a BMX because the 45Kg boy riding it puts out about 0.2 horespower and needs every single mechanical advantage he can muster. This can be considered an ‘extreme’ end of the scale where a small mechanical advantage can make a noticeable difference. At the other end, drag cars, high powered engine etc. it is also noticeable as the they measure performance down to 1000th’s of a second.

Let’s be honest, torque multiplication makes f’ all difference on dirt bike when changing from a 13,14 or 15 tooth front sprocket.

If you are going to worry about that there are heaps on other things like, fairing drag coefficients, tyre pressure, bike weight, rider weight and heaps of other factors that can be looked at and have a more noticeable effect on performance.

Remember we are giving advice to dirt bike riders, not moto GP riders.

:laugh: Thats true Moto that said for all my years around bikes and races and lucky enough to be around some major race teams I have never seen them talk about final drive ratios as you put up, although I am sure they all know how to work it out and it works.

Its been a great thread and I think on small capacity bikes it all matters, bring on the learning I say

TB

[Steve WyethMember]

Maybe so, but it requires the division of one number by another to give easy comparison between different gear ratio’s. As is evident by the posts following my first it seemed to help some people, which is after all the point of the thread in the ‘tech help’ section.

When racing you have so much experience around a team that you don’t need to work out final drive’s. You KNOW what gearing you need to run for different terrains and you would have spent many years testing to get that knowledge and experience.

That’s the difference between race teams and the average joe that we are talking about here. My post was to help people on this site better figure out gearing, not tell race teams how to do it.

Let’s leave your race team experience to the racers

[GregMember]

Its a tech tread Moto, and a good one, people can and will read what they want and should contribute what they want that is topic related. There is a lot to learn as they advance through their riding life. As far a way to technical responses go again the readers will work out what they want to read tech mined will read the lot and learn and others will get the simple answer they want and bail from the thread.

Now lets get it back on topic and learn as much we want

Cheers

TB

[Steve WyethMember]

You can delete this after you’ve read it but please consider the point of any thread asking for help is to provide it to the original poster. You can see from reviewing the posts all the unnecessary tech stuff did was to confuse the original poster.

Like almost all other areas of this site I won’t bother posting here anymore either as it always turns this way.

[GregMember]

Sorry you feel that way Moto I thought he got his question answered and there was other areas of it discussed. We try to keep the tech thread topic related (these discussions between you and I arent) I mentioned it, you asked why, I answered Mr Blue helped explain better then me and STM explained how its done else where I know Boony got his answer before that. To suggest people tried to confuse him is silly. All the good work you did earlier is only being undone now. The tech thread we try to keep on topic I know Mick moderated some posts in it earlier and he or other moderators can delete mine or will ring and talk about it if they feel they need to as you have done in the past.

Your answers were correct and good the topic just got expanded that doesnt take away from your work.

TB

[Bruce CurtisMember]

singletrackmind wrote:

Quote:

Mr Blue wrote:

Quote:

T/B is indeed correct about torque values on front sprocket size.

We did the same with the kids on BMX bikes, long crankarms as practical for little legs, and as small a front sprocket and compensate with the rear to retain the optimal gearing… a very switched on bloke showed me this years ago.

But as also stated small front sprockets wear chains faster.

Back in the day BMX bikes ran 44/16 but today the standard is 25/9. Similar ratio but in keeping with what Mr Blue was trying to achieve back in the day.

STM

STM this was up to last year, “back in the day” indeed…

Actually my daughter reckons she’s going racing again next season, and the philosphy is still the same, small front sprocket to tiny rear, unfortunately this costs about a squillion times more to setup than a standard 44/16.
Missy 13 has a bit of leg power as well, she screwed the left crankarm inside the crank last time she raced, now we need a new set of them as well..

Moto it is all information and I try not to dumb down anything, as that would make me a bad educator, and as i know Greg is still in that line of work it is our brief and training to give all reasons and theory to the students, how they interpret and utilise it is then up to them. However if you have all the aviliable information at your disposal you are less likely to make any changes that unwittingly put you behind the eightball again.

Boony, if you wish to fit a 15 tooth and the case saver impeeds this, make a new one out of a neoprane breadboard.

EDIT- wow a lot of stuff has transpired since I drafted this response around an hour ago, before pushing “submit”.

[Jason GreenMember]

How do you make a case saver out of neoprene breadboard?

[Bruce CurtisMember]

Re; changing the gearing to “smooth” out the power:

this works well on torquey bikes that suffer from “neither here nor there” internal gear ratios, and CAN enable you to better use the spread of power and ride without constantly destabilising the bike by overrevving, however if you have a gearbox with a very high 1st and 2nd you run the risk of never leaving the lower gears in S/T, and back to square one.
In your case Boony, if you are happy with your current gearing and it is a gearing “of all trades” just let it be and concentrate on riding like te tamworth wind.

[Bruce CurtisMember]

XRTRAILHACK wrote:

Quote:

How do you make a case saver out of neoprene breadboard?

Noeprane is a deceptively easy material to work with, can be cut with a fretsaw, but is as tough as a Scotsman with a mace.

You cut a template out of cardboard to suit the boltholes and the size of the sprocket, then get a breadboard of your preferred colour (blue for me) and cut to shape, drill the holes, trail fit, smooth out any irregularities with a heat gun and a good tool. Fit and violia a custom made trick looking case saver that costs peanuts, and it by all accounts works better than alloy or steel as it absorbs much of the shock of a chain derailment without pulling bolts through cases, and has a good memory, which means it will probably sustain SFA damage.

Have a look at the Pics of the Warlock, that’s what it has.

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