Bicycle Mechanics - Shifter Style question

I would like to make a flat bar bike out of an old Shogun lugged steel Mixte frame for my daughter.
I would like to use the 27" wheels with as wide a tire as I can find.
I have a bunch of these 27" wheels, both rear and front.

The rear I have in mind uses a six speed suntour freewheel.
I have another wheel with a Shimano 6 speed FW but it tops out at 25 teeth vs the suntours 28 Teeth.

I have a set of Shimano Brake/shifters off of a mountain bike. They were shifting a Shimano SIS system using Cassette style gears and braking Canti's. I assume the Brakes will do road brakes just fine

Could I buy a 7 speed FW and shift with these Brake Shifters?

Would the 7 speed Shifters shift a 6 speed FW if I just adjusted the derailer?

Would I need a new rear derailer- I currently have Suntour 3000 and several Shimanos that were friction shift circa 1986-7

Insights appreciated
Thank you


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Blending Bikes

Could I buy a 7 speed FW and shift with these Brake Shifters? Possibly ... it depends on the axle spacing ... if it looks like you can fit an extra cog in there with some space left over to fit the chain, go for it ... but if not it means respacing the axle and subsequently redishing the rear wheel to sit centered.

Would the 7 speed Shifters shift a 6 speed FW if I just adjusted the derailer? NO

Would I need a new rear derailer- I currently have Suntour 3000 and several Shimanos that were friction shift circa 1986-7 ... It MIGHT work with the suntour, but more often than not these two brands are not compatible. Also ... 6 speed derailleurs often don't cope with the 7 speed range. It also needs to be an SIS mech.

Yep! If you place a 6 speed freewheel next to a 7 speed freewheel you find the width of both to be the same. In other words, they stuffed 7 cogs in the space of a 6 cog freewheel. This requires a new shifter along with the new 7-speed freewheel. Generally, a 5-speed and 6-speed freewheel share the same cog spacing making the width of the 6-speed freewheel wider than the 5-speed freewheel. On older bicycles with narrower spacing this precluded updating the older frame to the newer 6-speed freewheel. Same thing with older 6-speed bikes. It's possible to screw on a new 7-speed freewheel in place of the 6-speed freewheel but it's never going to shift correctly with the old 6-speed shifter but sometimes you can get away with the same derailleur. With the shift to 8-speed cassettes the hub got wider precluding installing much less expensive 7-speed cassettes on the 8-speed hub but some innovative people sell a spacer that installs on the hub before sliding on the cassette cogs so you can get away with that. With 9 and 10-speed cassettes they made the chain so narrow that you now need a new crank and chain rings! That narrow chain will just fall between the chain rings and bind up. They changed the ratio from 1:1 to 2:1 between the shifter and derailleur as well. All this just to keep you buying new bicycles!

Yep! If you place a 6 speed freewheel next to a 7 speed freewheel you find the width of both to be the same. In other words, they stuffed 7 cogs in the space of a 6 cog freewheel. Unless it's a so-called "ultra" 6-speed, which uses 7-speed spacing to fit a 120mm axle.


... All this just to keep you buying new bicycles! ... or to keep me as a die-hard fan of non-indexed "friction" shifting. :)

Thanks for the Information. I learned a lot from this

I checked the spacing on all the 6 speed Freewheels.
Two are Sun tour perfect 14- 28 one is Suntour Pro Comp 14-26 and one Shimano UG 14,15,17,21,26,30

The Spacing on the gears, 5mm, matches the spacing on the 7 speed hub so I think I may give those brifters a shot. If not I can buy a 7 speed FW and play around with the spacers to center it. I never dished a wheel but I have plenty of spares to practice On.

I may consider a new 130mm cassete wheel later on. Are there any issues spreading a Mixte Frame?