Drivetrain Mods
07-10-09, 05:36 PM
#1
Member
Thread Starter
Join Date: May 2009
Location: Okinawa
Posts: 40
Bikes: 08 Motobecane Immortal Force, 06 Focus Black Forest Xtracycle, 02 GT Aggressor 1.0; 09 Bike Friday Pocket Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Drivetrain Mods
After much research and handwringing, I've pulled the trigger on a Bike Friday Pocket Sport purchase. With a top gear-inch of around 87", I can see a drivetrain mod in our near future.
The BF/PS comes with a 30-42-52 front triple and an 11-28 rear 8-sp cassette. From what I can gather, a swap to a rear 9-26 Capreo would involve a new rear hub, new derailleur and new shifter. The other option is to get a bigger chainring (I've heard of some folks bumping up to a 60-tooth!), but that might involve a new front derailleur. But, I might want to get longer cranks anyway.
Has anyone gone through this already? Any advice/observations?
Chris
The BF/PS comes with a 30-42-52 front triple and an 11-28 rear 8-sp cassette. From what I can gather, a swap to a rear 9-26 Capreo would involve a new rear hub, new derailleur and new shifter. The other option is to get a bigger chainring (I've heard of some folks bumping up to a 60-tooth!), but that might involve a new front derailleur. But, I might want to get longer cranks anyway.
Has anyone gone through this already? Any advice/observations?
Chris
07-10-09, 07:38 PM
#2
Senior Member
Join Date: Apr 2006
Posts: 3,653
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 380 Post(s)
Likes: 0
Liked 106 Times
in
80 Posts
My very early Pocket Rocket (1994) uses 46-60 front chain rings and a 11-28 rear cassette with 451 wheels and with that you end up with a top of 109 gear inches. My wife's 2006 Pocket Crusoe uses a triple up front with a 52-42-30 and a 9-26 Capreo with 406 wheels which gives a top of 104 gear inches. If she had ordered 451 wheels it would of had a top gear inches of 115 gear inches. She chose the 406 wheels because it is easier to find tires for it. Roger
07-10-09, 11:31 PM
#4
Member
Thread Starter
Join Date: May 2009
Location: Okinawa
Posts: 40
Bikes: 08 Motobecane Immortal Force, 06 Focus Black Forest Xtracycle, 02 GT Aggressor 1.0; 09 Bike Friday Pocket Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I find it's cheaper -- and more fun -- to do it yourself!
Chris
Chris
07-11-09, 12:45 AM
#6
Senior Member
Join Date: Jul 2008
Location: Puyallup WA US (near Seattle)
Posts: 90
Bikes: Bacchetta Giro 20, Specialized Roubaix, Kona Jake the Snake, Cannondale Super V, Electra Straight 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Capreo hub is probably your best option. The hub you will need for sure as it the only on that will take a 9 or 10 tooth cog.
You could try a Schlumpf Speed Drive internally geared bottom bracket. https://www.schlumpf.ch/antriebe_engl.htm However that would probably require a LBS experienced with it to install it as you may need a special tool and I am not sure it would work on a BF.
You could try a Schlumpf Speed Drive internally geared bottom bracket. https://www.schlumpf.ch/antriebe_engl.htm However that would probably require a LBS experienced with it to install it as you may need a special tool and I am not sure it would work on a BF.
07-11-09, 01:11 AM
#7
Member
Thread Starter
Join Date: May 2009
Location: Okinawa
Posts: 40
Bikes: 08 Motobecane Immortal Force, 06 Focus Black Forest Xtracycle, 02 GT Aggressor 1.0; 09 Bike Friday Pocket Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Capreo hub is probably your best option. The hub you will need for sure as it the only on that will take a 9 or 10 tooth cog.
You could try a Schlumpf Speed Drive internally geared bottom bracket. https://www.schlumpf.ch/antriebe_engl.htm However that would probably require a LBS experienced with it to install it as you may need a special tool and I am not sure it would work on a BF.
You could try a Schlumpf Speed Drive internally geared bottom bracket. https://www.schlumpf.ch/antriebe_engl.htm However that would probably require a LBS experienced with it to install it as you may need a special tool and I am not sure it would work on a BF.
Chris
07-11-09, 10:24 AM
#8
Senior Member
Join Date: Dec 2008
Posts: 1,821
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Have you considered SRAM Dual Drive?
It can give you 20 - 110 gear inches and will eliminate the front derailleur which complicates the fold with BF method of folding.
I have it on my NWT and am very happy with it.
Kam
It can give you 20 - 110 gear inches and will eliminate the front derailleur which complicates the fold with BF method of folding.
I have it on my NWT and am very happy with it.
Kam
07-11-09, 10:24 AM
#9
Senior Member
Join Date: Jul 2008
Location: Puyallup WA US (near Seattle)
Posts: 90
Bikes: Bacchetta Giro 20, Specialized Roubaix, Kona Jake the Snake, Cannondale Super V, Electra Straight 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
LBS's that specialize in small wheel bikes like folders and recumbents usually have access to the Schlumpf bottom bracket drives. They're not cheap though. I believe you are looking at around $500US. I've seen at least one Moulton with one and several 'bent trikes with them. Greenspeed offers them as an option on their trikes. The major difference between this and the few other geared BB's is that there are no cables, you shift it by hitting a large button in the middle of the cranks with your heel.
If you want to be silly about it you can mount triple chainrings on a Sclumpf combine it with a SRAM dual drive and have 162 gears.
If you want to be silly about it you can mount triple chainrings on a Sclumpf combine it with a SRAM dual drive and have 162 gears.
07-11-09, 02:50 PM
#11
Member
Thread Starter
Join Date: May 2009
Location: Okinawa
Posts: 40
Bikes: 08 Motobecane Immortal Force, 06 Focus Black Forest Xtracycle, 02 GT Aggressor 1.0; 09 Bike Friday Pocket Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Chris
07-11-09, 04:38 PM
#12
Senior Member
Join Date: Mar 2009
Posts: 283
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I think one thing that often can be easier with more specialized bikes is modifying your riding style a little, 87 gear in on those 406's 52/11 at 120rpms is 32mph.. How often you need to pedal that fast?
The 80/20 (or 90/10 or 95/5) rule is valuable with these types of bikes.
The 80/20 (or 90/10 or 95/5) rule is valuable with these types of bikes.
07-11-09, 08:45 PM
#13
Member
Thread Starter
Join Date: May 2009
Location: Okinawa
Posts: 40
Bikes: 08 Motobecane Immortal Force, 06 Focus Black Forest Xtracycle, 02 GT Aggressor 1.0; 09 Bike Friday Pocket Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I think one thing that often can be easier with more specialized bikes is modifying your riding style a little, 87 gear in on those 406's 52/11 at 120rpms is 32mph.. How often you need to pedal that fast?
The 80/20 (or 90/10 or 95/5) rule is valuable with these types of bikes.
The 80/20 (or 90/10 or 95/5) rule is valuable with these types of bikes.
I just got done doing a metric century on my full-size road bike. It's a 20-speed with 11-27 cassette and 34/50 crank, so 17th gear is roughly equal to the Pocket's top gear. It's conceivable that I may be happy with the gearing as is ...I'll see when it gets here!
Chris
07-11-09, 10:37 PM
#14
Senior Member
Join Date: Dec 2008
Posts: 1,821
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
When I climb very steeps hills (at least by my standard) I sometimes wish to have even a lower gear so I plan to try a smaller chainwheel (40T compared to the existing 46T) to get a range of 17 - 92".
Kam
