Mountain Bike Cassestte on Road Bike

I bought an almost unused 2007 Specialized Ruby Compact with 50-34 in the front and 12-27 in the rear. My legs are getting a real workout on the hills in the Santa Cruz Mountains (CA) where we have great weather in the winter. Today was one of those magical days with full sun and 60 degrees! On flats and moderate hills this bike just flies.

Anyway, though I am doing fine on most rides, some could use lower gearing. So, I emailed Specialized and they said they did not know anything and that I should contact Shimano. So, I called Shimano and they said that they do not test or recommend any mountain bike cassettes on their road bikes. Yet, many people in the local bike club have mountain bike gearing on their road bikes. I'm just not sure what brand of bikes they have. I really don't need totally low spinning gears, just one or two more.

I looked up 10 speed cassettes and found a company that makes them called IRD. One shop said that you could install these, but that you would need a Shimano mountain bike XT rear derailleur regular. Or, I could change the front smaller ring to have fewer teeth. That sounds interesting. Would the jump be too much? Can you do that without changing the whole crank? The next LBS said they didn't think it would work and I should get a triple.

This is a lot of conflicting info. I don't want to buy a bunch of stuff and then not have the bike perform well or be out the money for the parts. Does anyone have any advice on the best way to do this? Or do I need to just keep what I have?

To switch the cassette to anything larger than 27 or 28 you'll likely have to go to a mtb rear derrailleur. You could switch the cranks to a triple but you'd also likely need a new front derrailleur and/or shifter. Your LBS might be able to switch out your chain rings to smaller ones; that would be the easiest/cheapest fix.

I solved a similar issue via chainring. Cost me a total of $19, and I've got happy gearing for Seattle's hills. (Salsa makes some fine chainrings at good prices that are compatible and available in black or silver so they even match whatever scheme you've got currently.)

ETA: oooh, I just realized I did the chainring switch with TWO of my bikes, not just the one I mentioned above. It really is a very easy and cheap way to get lower gearing, and later you can switch back if you decide you liked the bigger rings after all.

Knot made a good suggestion with the chainring, although I think in your instance it would HURT shifting. If I have read your description of your bike accurately, you have a 50-34 compact crank.... which means that your front derailleur is at its limit with that setup. You can indeed put a mountain bike cassette on a road bike, but currently with some issues.(if you have a 10 speed drivetrain) Shimano does not make a 10 speed rear derailleur(mtn bike), so although someone can probably make something work, I don't believe without problems. People have mixed and matched Shimano and Sram together, but it does add a bit more noise to your drivetrain, and again, not without some issues. The thing that I would suggest(although costly) would be to add a triple crank. You would have to buy a front shifter, crank, bottom bracket, and front derailleur, but that if installed correctly would be your best bet. Down the road, I'm sure that Shimano will come out with a 10 speed mountain bike group, and then you'll be able to lower gearing even more and have something that actually works.

The compact cranks are indeed an issue for those of us that live in the mountains... they simply aren't low enough.(especially with 10 speed drivetrains) I'm hoping that Shimano and SRAM will realize this, but only with complaints from customers and many bike shops! :rolleyes:

I have a Shimano compact crank, and a 10 speed IRD 11-32 cassete, and it works perfectly. I happened to already have an Ultegra triple front derailleur, and that gave enough room that I didn't need a long cage rear derailleur. I remember when my lbs guy decided to try it out (without changing the rear derailleur), no one was sure it would work. That was over 2 years ago, and it's still working perfectly. No chain drop issues.

Redrhodie, I wondered if you could answer a question for me. When you are in your small chainring and your 32T does your rear derailleur bump up against your cassette?

Obviously, you are someone that understands "how" to shift your bike, because otherwise there would be some issues. At any rate, hopefully over time Shimano will come up with a 10 speed mountain group and that will solve most of the problems.

As I was heading out to take the dogs for a walk; I came up with another idea.;) IF you make sure that you have a Shimano "GS" rear derailluer, it definitely will work with a mountain cassette. If I remember correctly, the IRD cassette jumps from a 28T to a 32T which for some people is too big of a jump. The other option is to use a SRAM 10 speed mountain cassette which is a bit more even in the spacing on the cassette, but very expensive. ($300)

I love thinking about all of this sort of thing, thanks for sharing:D

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Originally Posted by ridebikeme

Redrhodie, I wondered if you could answer a question for me. When you are in your small chainring and your 32T does your rear derailleur bump up against your cassette?

Obviously, you are someone that understands "how" to shift your bike, because otherwise there would be some issues. At any rate, hopefully over time Shimano will come up with a 10 speed mountain group and that will solve most of the problems.

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I've actually (consciously) never used that gear combo, but I'm sure there'd be some rub, and maybe even stress on the rear derailleur??? I use my 28T as my lowest gear. I do go through a lot of chains, so that may be an issue (like 3 this past year). Granted, one rusted, so it wasn't a stretch issue, but I have had chains stretch.

ETA:

I just checked, and it does indeed rub (the front derailleur/chain) when in the 32T. The rear derailleur seems fine, but I'm guessing the big ring/lowest 32T gear wouldn't be a happy place.

The rub that I was talking about is the rear derailleur when you are in your 32t and your small chainring up front. You may indeed have a Shimano "gs" road derailleur, so you wouldn't have any rub where the derailleur hits the 32t. In terms of your front derailleur rubbing on your chain, that is simply because the derailleur limit screw is abit too tight. Whether you had a 32t on anything else as your low end on your cassette, that won't have any affect on chain rub unless the limit screw isn't set up correctly. The other factor here can also be the chainline of your bike. You might have your LBS check this the next time that you have a new chain replaced.

At any rate, thanks for the answers!:p

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Originally Posted by ridebikeme

The rub that I was talking about is the rear derailleur when you are in your 32t and your small chainring up front. You may indeed have a Shimano "gs" road derailleur, so you wouldn't have any rub where the derailleur hits the 32t. In terms of your front derailleur rubbing on your chain, that is simply because the derailleur limit screw is abit too tight. Whether you had a 32t on anything else as your low end on your cassette, that won't have any affect on chain rub unless the limit screw isn't set up correctly. The other factor here can also be the chainline of your bike. You might have your LBS check this the next time that you have a new chain replaced.

At any rate, thanks for the answers!:p

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Ah, you're right, it is the back derailleur that's rubbing. The front is actually not, there's bit of space there.

So, I appreciate all these answers, but I still don't know what to do. The IRD 11-32 works for Red Rhodie, but she has a triple and I have a double. I looked up the Salsa cranks, and they are for 5-9 speeds, not 10 speeds. I don't think I want all the expense of changing to a triple. It would kind of negate the fact that I got a good deal on this bike. The SRAM cassettes are over $300, I found an IRD cassette online for $119. I emailed the online seller, and he said an IRD 11-30 would probably work with my short cage derailleur and new chain. That would give me one gear lower. Is that enough? Would I still have problems shifting?

The bike shifts so nicely now, but today I hit a big hill and had to walk.... My DH tried getting up in a similiar gear (not his lowest) and he also had to walk... However, I notice my thigh muscles are getting stronger, and I even passed my teacher because she has lower gears and I could not ride that slow.

Before I go too far, I want to tell you that a crank is not compatible with a five through nine speed drivetrain! Obviously as you put more gears on the rear wheel, you need a narrower chain along with different derailleurs that are compatible.

Secondly, if indeed you have a short cage derailleur it is NOT compatible with a 11-30 cassette. The rear derailleur cage is not long enough for that size of cassette, and will hit the bottom of the 30t or 32 t cog. It is made for a 27T cog.

To answer whether this is a low enough gear for you, only you can answer that question. Only you know the ability that you have, and the terrain that you ride. ...

My suggestion here is to visit your LBS, and get answers that are accurate. The information that you are receiving online is very far from the truth and that can lead you into components not being compatible or not giving you what you want. Save yourself some money in the long run, get information that you can use, and go to a shop.

ridebikeme gives good advice. I just want to clarify that I have a compact double crankset, not a triple. But, it looks like I'm only getting one more gear with my setup than you currently have, since I use the 28T as my lowest gear.

If I were riding in the mountains, I'd get a triple. No doubt about it. My compact is fine for around here, but it's pretty flat.

I went to 3 LBS and asked the same questions. The first one said no problem to change to an IRD casette with MTB derailleur. The second one talked about chain capacity and said that IRD did not shift as well as Shimano. He thought I might be able to get away with a 12-30 (not 11-30) with my short cage derailleur, but would need a long cage for the 12-32 or 11-32. The third one said that I would need a long cage derailleur for the 12-30 and a MTB derailleur for the 12-32, but that it would not shift as well as now. Apparently, the spacing is slightly different than Shimano to avoid patent infringement. He recommended learning to stand up while pedaling uphill instead (which I have not mastered yet). How do you start that? Eventually Shimano will make a 10 speed MTB cassette (2011). The SRAM one would work, but it costs $330 and is 11-34 (which I don't need). I just emailed IRD and will see what they say. It never occurred to me when I bought the bike that I could not just simply get a larger cassette.

Okay, I have a little more info for you, but it still won't help you know if the IRD cassette will work on your bike (and in fact will make it more confusing--sorry).

According to my shop guy, who has a similar set-up as me, but with even lower gears than I have (Shimano compact double crankset with an IRD 10 speed 11-34 MTB cassette, and long cage derailleur), he can even use the 34T cog with no rub. He then tried to run the exact same setup on another of his bikes, and it wouldn't work at all. He figured out that the problem was the position of the derailleur hanger on the frame (which probably has another name, but I can't remember it :confused:). So unfortunately, it's another factor which may make it not work.

But, after thinking about this thread, I decided to upgrade myself to an ultegra 11-28 ten speed cassette. :) I'll get all the same gears I currently can use with my IRD, for 100 grams less. Woo-hoo, I'm excited! My IRD has around 7,000 miles on it, and it's still going strong, but the thing's a tank.

Let us know what you end up doing. Standing on hills will make you stronger, as will just working at it, but you don't want every ride to be miserable. You should be able to get a better range. Good luck!