Bodging a very compact double
#1
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 372
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Bodging a very compact double
At the moment I have a 50/34 double on my 'cross bike using a hollowtech II bottom bracket.
I understand that with a 110BCD crank the 34 is my limit. What I'm wondering is if I could buy a mountain bike triple, say a 44/30/22 and remove the 22 ring and use it as a very compact double for my 'cross bike.
I'd prefer to stick with the current BB as when summer comes round I'll be back on the road more and wanting the 50/34. But off road and with my love of spinning low gears the bike is completely overgeared.
I understand that with a 110BCD crank the 34 is my limit. What I'm wondering is if I could buy a mountain bike triple, say a 44/30/22 and remove the 22 ring and use it as a very compact double for my 'cross bike.
I'd prefer to stick with the current BB as when summer comes round I'll be back on the road more and wanting the 50/34. But off road and with my love of spinning low gears the bike is completely overgeared.
#2
Hustler
Join Date: Sep 2008
Location: Parkton
Posts: 103
Bikes: 09 Masi Rando "Gay Bob", 91 Serotta NHX, 12 Kona Raijin
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
It might be easier and cheaper to put a low geared mountain cassette on the rear and not worry about switching the crankset out, because with that you'll have to adjust the front derailleur a good bit every time you switch.
#3
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 372
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Changing the cassette would give me the lower ratio. But having the big ring as being a 44 would remove the fact that I never use anything above 50/15 and give me a more usable spread of gears.
Cost wise I'd expect it to be the same as one is mech + cassette and the other is crankset. The more I look at it the more I think I'd probably use the 44/30 on the road as well as I'm more of a long distance cyclist in a hilly area.
34/25 = 1.36
30/25 = 1.2
34/32 = 1.06
30/32 = 0.93
50/12 = 4.16
44/12 = 3.66
Cost wise I'd expect it to be the same as one is mech + cassette and the other is crankset. The more I look at it the more I think I'd probably use the 44/30 on the road as well as I'm more of a long distance cyclist in a hilly area.
34/25 = 1.36
30/25 = 1.2
34/32 = 1.06
30/32 = 0.93
50/12 = 4.16
44/12 = 3.66
#4
cycles per second
Join Date: Oct 2003
Location: Minnesota
Posts: 1,930
Bikes: Early 1980's Ishiwata 022 steel sport/touring, 1986 Vitus 979, 1988 DiamondBack Apex, 1997 Softride PowerWing 700, 2001 Trek OCLV 110
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 44 Post(s)
Liked 71 Times
in
48 Posts
I understand what you're trying to do. I bought a used 5-arm "micro" triple crank (94/58mm BCD) and put Ritchey 44x29 "2 x 9" rings on it and use it on my commuter/tourer with an 11-28 cassette (or 11-34 for mountainous touring).
But can you do it with 104mm BCD Hollowtech II cranks? I dunno. Can you even get a 30T ring for one of those? If you find a Hollowtech II crankset with those rings, do they even sell them without BB cups, and if so, would the crank even work in your current BB cups? And can you lower your front derailer enough for a 6T drop in the big ring? It's about 2mm per tooth so a 6-tooth change would require lowering the FD by about 12mm (almost 1/2 inch).
If you have gears low enough, I'd stick with what you have. If you need lower, I agree with Rick on the wide range cassette.
But can you do it with 104mm BCD Hollowtech II cranks? I dunno. Can you even get a 30T ring for one of those? If you find a Hollowtech II crankset with those rings, do they even sell them without BB cups, and if so, would the crank even work in your current BB cups? And can you lower your front derailer enough for a 6T drop in the big ring? It's about 2mm per tooth so a 6-tooth change would require lowering the FD by about 12mm (almost 1/2 inch).
If you have gears low enough, I'd stick with what you have. If you need lower, I agree with Rick on the wide range cassette.
#5
Senior Member
Join Date: Jun 2007
Location: A Coffin Called Earth. or Toronto, ON
Posts: 12,257
Bikes: Bianchi, Miyata, Dahon, Rossin
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 5 Times
in
5 Posts
you'll probably want the road actuation MTB FD if you go this route.
can't you just buy a 44T 110BCD chainring? unless you really want that 30T.
can't you just buy a 44T 110BCD chainring? unless you really want that 30T.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
#6
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,656
Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 2026 Post(s)
Likes: 0
Liked 1,095 Times
in
741 Posts
Does anyone make a 30T middle ring MTB crank? The ones I've seen are 20 or 22/32/42 or 20-22/34/44.
Unless you can find a 30T ring for a MTB crank, just replace the 50 on your current crank with a 44 or 46T ring.
You will have to replace the bb no matter what other crank you use.
Unless you can find a 30T ring for a MTB crank, just replace the 50 on your current crank with a 44 or 46T ring.
You will have to replace the bb no matter what other crank you use.
#7
Real Men Ride Ordinaries
Join Date: Sep 2008
Posts: 3,723
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 3 Times
in
3 Posts
IT's not very compact unless you run a 46/24 using the middle and triple of a 110/74. It actually works remarkably well, and can be built with almost no overlapping gears, while still allowing you to climb most anything.
#8
Likes to Ride Far
I recommend going the route of getting a standard road triple crankset and putting custom chainrings on the inner and middle positions of that. This will make it easy to get something that matches your current bottom bracket. The BCD on those is normally 130mm for the middle (and outer) rings and 74mm for the inner ring, so you'll be able to get any combination you want. I do this and run a 26-42 setup on my commuting/touring bike (with a 12-27 9-speed cassette) and a 28-46 on my racing/road bike (with an 11-26 10-speed cassette) and lovely the gear choice I get on it with the simplicity of a double cransket (I spin at a high cadence all the time and do a lot of long climbs, so the gears on the compact are just not in the right range for me).
EDIT: If you go for a big difference in tooth count between the inner and next ring like this then make sure you get some sort of chain retention device to prevent chain derailment off the inner chainring when doing fast down-shifts.
EDIT: If you go for a big difference in tooth count between the inner and next ring like this then make sure you get some sort of chain retention device to prevent chain derailment off the inner chainring when doing fast down-shifts.