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Old 09-06-09, 06:17 AM   #1
karavshin
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Mixing Ultegra crankset with MTB shifting

My gearing is too low. The best solution is to convert the front crankset to a road style which offers a 53T ring.

Currently I have a Shimano SLX Hollowtech II crankset (44-32-22) + SLX FD + Deore LX 3spd flatbar shifter.

I'd like to replace the crankset with an Ultegra. Probably a 53-36. Another option might be a 3-ring Ultegra if I can find one.

Anyway, what I want to know is what i can/must do with the SLX FD and my Deore LX shifters.

Can the SLX FD properly shift on an Ultegra crankset (whether it's 2 or 3 rings)? If not, and I have to put a real road front derailleur on, will the Deore LX shifters be able to drive that derailleur? Or do I have to find some Road flat-bar shifters (uh oh).

If I have to use a road FD, the ultegra will be bottom-pull, when my bike is set up for top pull. I think I can solve that with the aid of a Speen "umlenker" adaptor. Has anyone used these? It sounds cleaner and easier than a pulley system.
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Old 09-06-09, 06:30 AM   #2
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You might be OK with the SLX FD, but best performance will come from one meant to take the larger diameter chainrings (road FD).

Your existing shifters will be fine. If you are using a double crank, then make sure you set the limit screws correctly and match the shift to the 1-2 position on the shifters. You will just not shift all the way to the 3rd poosition on the shifter. With a triple crank, just set up as usual.

Have you considered just switching to a Shimano LX "trekking" crankset (48-36-26) and an 11-23 road cassette? Might be a lot easier...
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Old 09-06-09, 06:43 AM   #3
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It seems to me like your proposed plan has a lot of maybe's.

If you switch from a crankset with a 44t big ring to one with a 52 or a 53, you will almost surely need to replace the front derailleur. The issue is the curve of the cage. Yours has a radius that's too amall and you'd have to install it way high on the seat tube to keep the heel of the cage from hitting the chainring.

Switching to a road front derailleur creates 2 new problems:

The first is pull direction. I've not seen the german gizmo that you referred to. Some of the Shimano mountain derailleurs have a system that provides for either top pull or bottom pull operation so I assume this is similar. I'm going to say it might work but I really don't know.

The second is pull ratio. Shimano road and mountain front derailleurs have slightly different pull ratios. I'm not sure how big of an issue this really is. Back in the mid to late 90's tandem manufacturers routinely spec'd flat bar tandems with road cranksets and front derailleurs paired with mountain bike shifters. They worked just fine.

Yet another "maybe" may arise in installing your new crankset. Depending on your frame's design, you may encounter interference between your new bigggest chainring and the right chainstay.

Now is the time when you get to decide what kind of bicyclist you are. If your objective is "just to ride", my advice is to sell the bike that you have and start over with one that's equipped more to your likeing. If you are the kind of person who "likes to tinker", sometimes that process can be almost as much fun as riding.
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Old 09-06-09, 06:54 AM   #4
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the road FD does not have the same cable pull as the MTB FD so swapping them might not make it work too well if you use a triple. A double might work, but will be slightly finicky.

you'll need a compact with non-shimano chainrings if you're going for a 36/53 since shimano doesn't offer a 53T or 36T in 110BCD and 36T on a 130BCD crankset is impossible.

you'll be stuck with 38/53 regular size road or 36/52 compact
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Old 09-06-09, 09:43 AM   #5
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Originally Posted by Retro Grouch View Post
It seems to me like your proposed plan has a lot of maybe's.

If you switch from a crankset with a 44t big ring to one with a 52 or a 53, you will almost surely need to replace the front derailleur. The issue is the curve of the cage. Yours has a radius that's too amall and you'd have to install it way high on the seat tube to keep the heel of the cage from hitting the chainring.

Switching to a road front derailleur creates 2 new problems:

The first is pull direction. I've not seen the german gizmo that you referred to. Some of the Shimano mountain derailleurs have a system that provides for either top pull or bottom pull operation so I assume this is similar. I'm going to say it might work but I really don't know.

The second is pull ratio. Shimano road and mountain front derailleurs have slightly different pull ratios. I'm not sure how big of an issue this really is. Back in the mid to late 90's tandem manufacturers routinely spec'd flat bar tandems with road cranksets and front derailleurs paired with mountain bike shifters. They worked just fine.

Yet another "maybe" may arise in installing your new crankset. Depending on your frame's design, you may encounter interference between your new bigggest chainring and the right chainstay.

Now is the time when you get to decide what kind of bicyclist you are. If your objective is "just to ride", my advice is to sell the bike that you have and start over with one that's equipped more to your likeing. If you are the kind of person who "likes to tinker", sometimes that process can be almost as much fun as riding.
I briefly had a bike that was set up with XT front and Ultregra triple der and crankset that ran without any problems. Any difference there might didn't impace performance.
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Old 09-06-09, 03:03 PM   #6
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From a 44 big ring to a 53 is much too large of a change. Just say no.
You haven't said what cassette you are running in the back. A change in the back may be all you need.
If you want a road bike it's best to buy a road bike. Trying to convert what you have to a road bike will carry a big price tag and will probably yield undesirable results.
Estabro's comment: "Have you considered just switching to a Shimano LX "trekking" crankset (48-36-26) and an 11-23 road cassette? Might be a lot easier..." is a good one.

Al
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Old 09-06-09, 03:18 PM   #7
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Originally Posted by karavshin View Post
My gearing is too low. The best solution is to convert the front crankset to a road style which offers a 53T ring.
<snip>
I'd like to replace the crankset with an Ultegra. Probably a 53-36. Another option might be a 3-ring Ultegra if I can find one.
You can't run a 36-tooth chainring on a standard Ultegra crankset- I assume you'll be getting a "compact" crank. 36 to 53 is a pretty huge jump, but stranger things have been done:
http://sheldonbrown.org/hetchins/
http://sheldonbrown.org/hetchins/source/3.html

I've heard of people using MTB-type front derailleurs on larger chainrings with acceptable results, but the better setup is the Shimano FD-R453 derailleur. This is set up for the longer "mountain" cable pull, but curved to fit larger "road" chainrings. I've used several on my recumbents and they work perfectly:
http://home.comcast.net/~jeff_wills/...s/bike019a.htm

The Speen Umlenker thingamabob looks like what you need if your bike is set up for top-pull cables. If you put on a FD-R453 derailleur, I think you'll need one with the "XC" suffix. Here's the brochure: http://www.speen.de/Docs/Specification%20Umlenker.pdf
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Old 09-06-09, 03:28 PM   #8
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I briefly had a bike that was set up with XT front and Ultregra triple der and crankset that ran without any problems. Any difference there might didn't impace performance.
the spacing is the same, but the cable pull isn't.

it would be bad to mix XT FD with ultegra shifter or the reverse with whatever triple, but using XT FD and XT shifter is fine.
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Old 09-07-09, 12:58 AM   #9
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To change the smallest number of things, I would just switch your 44-32 chainrings for 48-36. You then won't need a new front derailleur, which, as mentioned above, would introduce a lot of complications. I assume your MTB cassette has an 11-tooth cog on it. The 48-11 gear should be sufficient, even with 26" wheels; if it isn't, then just learn to put power into the pedals while spinning them faster (work on this by using lower gears than normal on flat terrain).
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Old 09-07-09, 01:52 AM   #10
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To change the smallest number of things, I would just switch your 44-32 chainrings for 48-36. You then won't need a new front derailleur, which, as mentioned above, would introduce a lot of complications. I assume your MTB cassette has an 11-tooth cog on it. The 48-11 gear should be sufficient, even with 26" wheels; if it isn't, then just learn to put power into the pedals while spinning them faster (work on this by using lower gears than normal on flat terrain).
+1
This is another of those questions that keeps popping up, and I can't really figure out what kind of riding people do to actually need this change. On my MBT-based commuter I'll be using a 42 big this autumn/winter.
This will get me to >25 MPH/40 KMH before spinning out, which I think is just fine for riding in an urban environment.
Along a 16 mile/25 Km commute I reckon I'll have two descents where I'm at risk of spinning out, for a total time when I can't pedal effectively of maybe 30 seconds. Coasting for those seconds isn't going to affect either my travel time or the work-out value of my ride in any significant manner.

When that crankset gets worn out I might go slightly bigger, but that would be mainly to shift more ride time onto bigger cogs which doesn't wear as fast as the smallest ones.
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Old 09-07-09, 02:56 AM   #11
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+1
This is another of those questions that keeps popping up, and I can't really figure out what kind of riding people do to actually need this change. On my MBT-based commuter I'll be using a 42 big this autumn/winter.
This will get me to >25 MPH/40 KMH before spinning out, which I think is just fine for riding in an urban environment.
Because I'm using 406mm wheels. Spinning out at 33kmh sucks.
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Old 09-07-09, 07:35 AM   #12
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sounds odd that your bike came with a 22-33-44 cranks and 406mm wheels.
is it a folder or recumbent?

my 20" folder came stock with a 50T, so it just seems odd that yours has a MTB crank.
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