Tourney Gear Swap Question
#1
Member
Thread Starter
Tourney Gear Swap Question
My bike has an A050 front derailleur and an A070 rear derailleur. Current setup is 42/52 in the front and 12-28 7-speed in the back. Is it possible to swap the front out with a 34/50 crank and the rear with a 14-34 without changing anything else? Thanks!
#2
Old fart
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,777
Bikes: Several, mostly not name brands.
Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3582 Post(s)
Liked 3,394 Times
in
1,928 Posts
Probably not. You'll likely need a longer chain and possibly a longer cage rear derailleur.
#3
SE Wis
Join Date: Apr 2005
Location: Milwaukee, WI
Posts: 10,499
Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400, 2013 Novara Randonee, 1990 Trek 970
Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 2740 Post(s)
Liked 3,387 Times
in
2,050 Posts
Rear specs and capacity
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
#5
Senior Member
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,547
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18350 Post(s)
Liked 4,502 Times
in
3,346 Posts
Rear specs and capacity
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
OP wants 34T. That may be pushing it a bit for a 34T rear sprocket, although there may be options to increase the hanger length.
(34-14) + (50-34) = 20+16 = 36, so the derailleur capacity should be OK.
Front derailleurs are often pretty forgiving of changing chainring sizes. Capacity is a bit of a difference and will depend on the seat tube angle.
#6
Senior Member
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,547
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18350 Post(s)
Liked 4,502 Times
in
3,346 Posts
And changing from 28T to 34T on the rear means you want lower gears.
You can achieve some of the same by going with even a smaller crankset. 48T/30T? Smaller?
Ultimately you could probably keep the current 12/28 cassette, or even go to 11/28.
#7
Senior Member
Join Date: Sep 2015
Location: /dev/null
Posts: 675
Bikes: Soma Double Cross Disc (2017), red Hardrock FS (circa 1996)
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 217 Post(s)
Liked 155 Times
in
102 Posts
A side note: 12-28 is a cassette, but can you get a 14-34 7 speed cassette now? AFAIK, Shimano no longer makes them. 14-34 freewheels - yes, but not the cassettes. Of course you can get a Sunrace 11-34 cassette or build a custom one.
#8
Member
Thread Starter
That puts the capacity at 37T with a 28T max rear sprocket size.
OP wants 34T. That may be pushing it a bit for a 34T rear sprocket, although there may be options to increase the hanger length.
(34-14) + (50-34) = 20+16 = 36, so the derailleur capacity should be OK.
Front derailleurs are often pretty forgiving of changing chainring sizes. Capacity is a bit of a difference and will depend on the seat tube angle.
OP wants 34T. That may be pushing it a bit for a 34T rear sprocket, although there may be options to increase the hanger length.
(34-14) + (50-34) = 20+16 = 36, so the derailleur capacity should be OK.
Front derailleurs are often pretty forgiving of changing chainring sizes. Capacity is a bit of a difference and will depend on the seat tube angle.
#9
Member
Thread Starter
By changing from 11T or 12T to a 14T in the rear, you may be saying that you don't need the highest gears.
And changing from 28T to 34T on the rear means you want lower gears.
You can achieve some of the same by going with even a smaller crankset. 48T/30T? Smaller?
Ultimately you could probably keep the current 12/28 cassette, or even go to 11/28.
And changing from 28T to 34T on the rear means you want lower gears.
You can achieve some of the same by going with even a smaller crankset. 48T/30T? Smaller?
Ultimately you could probably keep the current 12/28 cassette, or even go to 11/28.
#10
Member
Thread Starter
That was my mistake as I did not clarify - yes, this is a freewheel. Thank you for catching that.
#11
Member
Thread Starter
Rear specs and capacity
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
https://bike.shimano.com/en-EU/produ...0/RD-A070.html
Nothing available on specs for front. try it and see.
I found some specs for the A050 under the Technical Documents section of the Shimano website [the A050 is discontinued]. Looks like everything I found for the A050 lists the smallest gear size as 39.
So I may just replace the FD-A050 with an FD-A070. The chainstay angles and chainlines are the same values for both units. The band clamp diameters appear to be different. Based on the info below from Shimano, is it safe to presume an A070 can be retrofitted to a frame currently using an A050 provided the A070 uses an adapter? Is there anything else I need to take into consideration when doing a swap like this? Thank you.
A070
Mount Clamp Band: 28.6mm [w/ S size adapter]
Mount Clamp Band: 31.8mm [w/ M size adapter]
Mount Clamp Band: 34.9mm
A050
Mount Clamp Band: S(28.6mm)
Mount Clamp Band: M(31.8mm)
#12
Senior Member
Join Date: Sep 2015
Location: /dev/null
Posts: 675
Bikes: Soma Double Cross Disc (2017), red Hardrock FS (circa 1996)
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 217 Post(s)
Liked 155 Times
in
102 Posts
Are you sure you need to change the FD? Do you think that with the new crankset the difference between the large and the small chainring will be so high that the chain will drag on the FD cage when it is on the small chainring in the front? I would first try it and see.
#13
Member
Thread Starter
https://sheldonbrown.com/gloss_ca-g.html#capacity
Are you sure you need to change the FD? Do you think that with the new crankset the difference between the large and the small chainring will be so high that the chain will drag on the FD cage when it is on the small chainring in the front? I would first try it and see.
Are you sure you need to change the FD? Do you think that with the new crankset the difference between the large and the small chainring will be so high that the chain will drag on the FD cage when it is on the small chainring in the front? I would first try it and see.