Doug64

I need some help and ideas. I am responsible for the maintenance of our school district's Bike Safety bike fleet. We have 36 bikes used to teach bike safety to the fifth graders in our school district. The bikes are 21 speed, but we don't want the kids to use the front derailleur. Most are not functioning anyway. We would like to find a satisfactory way to limit the use to the middle chainring. The city that donated their old fleet to us when they upgraded, tried to use the limit screws to do this. It has not worked very well for us.

Do any of you know of a good way to essentially make this a 1x7 using the existing crankset, and the middle chainring?

Your ideas are welcome and appreciated.

Bill Kapaun

Limit screws and disconnect shift cable.
If you can remove the shifter, better yet.

ThermionicScott 

+1. I'd use the limit screws to freeze the FD in place, then possibly bend the FD cage into a wider shape to obviate chain rub at the extremes.

bwilli88 

Take off the front derailleur and shifter.

OneIsAllYouNeed

Cut the shift cable short and screw it under a bottle boss or under the BB.

HillRider

Why won't the limit screws work?

Andrew R Stewart 

Limit screws only need to be long enough to control the intended travel range. Depending on the geometries of the der (and the limit screw tabs) this might mean they're not long enough to limit the cage to the, aprox, middle of the range. OneIsAllYouNeed has it right. I've used a short length of cable with the head nestled into the frame cable stop (or the rear der's adjusting barrel) many times for various reasons, to limit der travel. Andy

squirtdad

Take off the front derailler and take the cable out of the shifter. Fast, simple, should be 5 th grader fool proof, and reversible if ever needed

I think it is cool that your school district has this program

Doug64

Thanks to everyone. This winter I'll try some of the suggestions.

It is a great program. We finished our first fall class yesterday doing almost 5 miles on the "Community Ride". It is their graduation ride and allows them to practice everything they learned. We were caught in a driving downpour, but the kids in our group still wanted to ride some more after returning to the school grounds while waiting until the last group finished. The class is divided into groups of 4-6 kids that are led by at least 2 adults.

Miele Man

If you need a longer limit bolt you should be able to buy one at a decent hardware store. I've also used rear dropout bolts as a derailleur limit bolt at times.

Cheers