re gearing a sachs columbia

so i want to re gear my rear wheel on my sachs/colombia mopet and im having a problem cause this gear on it is the same side as the brake plate. the opening is 105mm wide. i was on treats and saw a 98mm 4 bolt gear that looks close and then i could open up the hole to match. anyone run into this problem before? any help is appreciated

Re: re gearing a sachs columbia

German ebay has front sprockets. The exchange rate now favors the US dollar so they are waaaaay cheaper than aecustom solution to the rear. However, youll need a dremmel.

Re: re gearing a sachs columbia

How do you plan to open up the center?

Re: re gearing a sachs columbia

Kevin Bishop /

Get a garelli 36 rear it works with minor hole mods

Re: re gearing a sachs columbia

Kevin Bishop /

^nevermind

Re: re gearing a sachs columbia

I have opened the center hole on a lathe. It might be easier to get a sprocket with the correct center and grind or drill the bolt holes. It sounds like the Garelli sprocket Kevin mentioned might need the bolt holes adjusted a little.

Re: re gearing a sachs columbia

Getting the center correct is the most important of course. Just gotta figure which is less steps. Chucking up or sharpie mark and drill.

Re: re gearing a sachs columbia

for $26 i might buy one and see if i can bore it out a bit i will report back

Re: re gearing a sachs columbia

Did you ever figure anything out for this?

Re: re gearing a sachs columbia

Italian "Z" sprockets should be same, and the derbi ones, tomos are smaller center hole and slightly smalle bolt spacing but you can widen it out and make it work, I have, but there's available ones that're easier.

just to save the info it's 66m diagonal betw bolt holes and 42.5mm center hole. The derbi ones are like 65mm corner to corner with a much bigger center and totally fit with very minimal work. the garelli are like 68mm diagonal again basically no effort to fit.

I also usually prefer the bigger front sprocket. you do have to grind the case some to clear a 12 or 13mm front sprocket but it's cheaper and to be totally honest I could 100% grind the cases and slap a front sprocket on cheaper and wayyy faster than pulling the back wheel removing all that, getting all the bolts out for the rear sprocket, fiddling the new ones in, setting the retaining ring, shortening the chain and reassembling it all. people get nervous like grinding's gonna be a big chore, it's not, just a dremel bit and <15 minutes.

note: FRONT CANT FIT BIGGER THAN 13. just fyi.

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