Changing gears from levers to triggers

Funkydee

Hi people.
I have a conversion I'd like to try, but not sure how possible it is.
My jargon is dodgy, excuse the lack of it here.
I'm encouraging my partner to start cycling again, but have a VERY limited budget. Besides I like the challenge of working on a project, so here goes.
I have an old Apollo Kimera womens bike picked up cheaply, my partner has a lack of confidence which means she needs a step through frame. It's in decent nick, looked after pretty well by last owner etc. It's worth improving upon, too good to dump. But, it has cantilever brakes (YUK!) and Shimano SL TY15A thumb shifters. (hmmm)

Changing brakes to V brake is no prob for me, done that before and am on the case.
But, those thumb shifters are causing problems for my girl, so I want them gone, and so does she as she has briefly ridden a rapid fire style changer and it's just better for her (and I.M.O. the whole world).
The front changer may be the more straightforward, (???) as it has 3 stops, the current set up has 3.

Question 1
Do the rapidfires/triggers push/pull the front mech/derailluer over by the right amount on all bikes ie does the front chainset have a standardised distance between 'cogs' allowing a smooth change even when they were not originally designed for a trigger changer?

The Apollo is a 15 gear, (obviously 3x5). Most rapidfires are for 6-9 gears.

Question 2
If I get a 7x rear trigger, can I just set the derailler limiter screws to stop the derailluer after 5 gears, rendering the last 2 'clicks' redundant? Will this cause me massive problems, perhaps cable slackening or something?

Question 3 Would the 7 speed use the correct cable length increments for a 5 speed cassette?

Question 4.
Are there such things as 5x rapidfires/trigger changers which would work and NOT be expensive?

Hope this makes sense.
Any answers/input gratefully received, keep it simple for though if you can.
Many thanks,
Funkydee

cooldad

Front should be fine but not the back. 7 speed will not pull enough cable for a 5 speed freewheel. You can probably swap it for a 7 speed freewheel though.
I don't think you can get 5 speed rapidfires.

The Rookie

https://sheldonbrown.com/cribsheet-spacing.html#k7fw
scroll down and see the sprocket spacing 5 speed is 5.5mm and 7 speed is 5mm, so after 4 shifts it would be 2mm - not going to work.
As CD says you can quite possibly get a a 7 speed freehwheel to fit and then get 7 speed shifters. (such as the classic ST-EF 51's with integral brake lever).

That said properly indexed and decent quality thumb shifters can be very pleasant to use.

Funkydee

Thanks Guys, very useful.
I suspected as much on the rear.
I also suspect I'll have more questions re changing to a 7 speed freewheel.
I can source one easy enough, I hope in budget.
I'll find a few you tube videos for instructions. I'll buy a tool for removal and fitting, making sure I get the right one ie freewheel/chainset etc.
After that, if I'm struggling, I'll be back.
Many thanks
Funkydee

Funkydee

cooldad wrote:

You can probably swap it for a 7 speed freewheel though.

Just checked RJ the Bike Guy vid which says replacing 5speed with a 7speed freewheel may not work as the 7 speed will be too wide and would rub against the frame.

Is this highly likely to be true?
Any tips as to what to look out for when finding a replacement if that's the way I go?
F

Funkydee

And also, just thought, is the chain link size always going to fit a 7 speed if it's designed for a 5 speed?
It's becoming complex!

The Rookie

Chain is the same for 5 and 7, but I'd be fitting a new chain anyway.

Measure up and find out if you have enough clearance outboard of the 5th speed for another two, you'll need about 12mm.

Funkydee

The Rookie wrote:

Chain is the same for 5 and 7, but I'd be fitting a new chain anyway.

Measure up and find out if you have enough clearance outboard of the 5th speed for another two, you'll need about 12mm.

re measuring, thanks Rookie, will do, rain stopped play today, then dark stopped play til tomorrow.

re new chain, I hear what ur saying, but I'll do the easy bits first then work up to more expense.
F