Please help with crankset replacement
 

I am thinking of changing the stock chainring (Shimano FC-T551, 26/36/48t) on my Surly Ogre to Shimano Deore XT M782 (22/30/40t), which I found online for a 35% discount. Depending on how much needs changed, I might just ask my LBS to do the work as I am a complete patzer. But I would like to have a notion of how much would be involved before proceeding.

First question. It doesn't come with a bottom bracket. Will I need to replace the stock BB?

Second question. Will I need to change the FD?

Third question. Will I need to change shifters/cables?

Fourth question. I guess I will need a different chain for running such a different number of teeth, right? Any suggestions?

Fifth question. Anything else I should be aware of before I start?

For reference: http://surlybikes.com/bikes/ogre/bike_specs

Why would you want to change it?

# 2 - no
# 3 - no
# 4 - no, because you are going to smaller chainrings. You may need to remove a link or 2 so the chain does not go slack in small-smallish combinations. If you were switching to larger chainrings, you would need a longer chain to handle big-big.

Lower gearing.

Lower gear for hills while loaded touring. Plus, I really don't have much need for any gears as high as the stock 48t allows. Of course, I have no idea if this change will produce less or more redundancy in gear choices.

If you do this, you will need to shorten your chain. What BB/axle you need will depend on what the new crank needs. Could possibly be the same. Switch would give you much lower gearing overall. Is that your intent? 40t is pretty small for a large ring ridden on roads, but I don't know what your riding is.

Thank you!

Now it sounds like I might be able to handle the swap myself and save some money!

Redundancy is probaly the same. You can enter your chainring and cog sizes into an online gear chart if you want to see the specifics.

# 1 - I don't know, but someone here probably does.
# 5 - Don't think so

Your cassette has a 36t cog. 36x26 is already pretty low for your lowest gear. Could you just replace the current small chain ring with a smaller one?

Yeah, I used BikeCalc.com - Bicycle Gear Inches Chart to see a change from a low of about 20" to 17.5". And a high of 104.4", or a top speed of about 28 mph (i.e., at 90 rpm). Fully loaded, the only way I could get that much speed is on a pretty steep or long downhill, anyway.

You only need one change.

Replace the 26 Chain Ring with a 22 Chain Ring and you are good to go.

I don't know! Please just pretend I am an idiot and advise from there...

OK, second person to tell me this, so I need to look into this.

Kind of starting over, then, with my questions. Anything else need replacement to change just the smallest chain ring?

Get some muscles in you legs and just have fun riding.

Try going down Two Size Smaller tires. I rolled Fully Loaded on 700 X 28's

http://i256.photobucket.com/albums/h...ril2010046.jpg

I am not sure exactly what you are saying. It did seem that going to Deore XT would be a worthwhile quality upgrade, especially with a 35% discount.

I hope that my 29 x 2.1 will work well on the Katy Trail. After that, I may consider a tire change, depending on wear with riding from Indiana to the St. Louis trailhead. Since purchasing my bike at Christmas, I only have about 600 miles on it so far, so I'd rather not buy any new tires yet.

If this is what you have, looks to be of decent quality. (I'm not familiar with it.) http://cycle.shimano.co.jp/media/tec...9830799952.pdf
You would have to remove the drive side crank structure to get to the inner ring. You would have to first locate an appropriate smaller inner ring. FD would likely need fine tuning with smaller ring.

The front derailleur MAY have trouble with the range from a 22 to a 48 large ..... not sure

It won't...

Agree with you.

I agree, changing just the smallest chainring is easier. 2.1 tires will do well on the Katy Trail - I don't know what tread you have, but it doesn't have to be very aggressive. Larger air volume, somewhat lower pressure works well on the Katy's surface. I also find a 36 chainring works well for me on my touring bike in flat land (which is what you have mostly between Indiana and Missouri), but that's purely subjective.

I'm not up on all the new BB styles, but it appears the 2 cranks use different TYPES of BB's.

For some unknown reason, I cannot get that link to load in Firefox or IE.

The stock tires are WTB Nano 29 x 2.1. They have a single raised middle line, which seems to work well on pavement, though I have absolutely no other tire experience to compare.

Aidoneus, Replacing the inner ring for a 22T or a 24T is the best and least expensive option. You may want to order a chain catcher to keep the chain from falling onto the bottom bracket shell (it very well may not) during the down shift. While you may not use the small cassette cog with the outer chain ring, it can be handy when using the middle chain ring.

Brad

BTW, another reason I was (am?) considering the full change is to change the crank length. The stock arm is 175 mm, and I wonder if it would be easier on this old man's knees to go with a shorter crank. I've read several posts online (e.g., BikeDynamics - Bike Fitting Specialists - Crank Arm Lengths) that suggest a shorter crank makes higher cadence easier. I have improved somewhat over these two months to an average cadence of about 80 rpm, but much faster makes me feel like a fishing bob. Of course, it might just mean I need to raise or adjust my seat--before I leave for a tour in May, I think I will see about a professional fit.

To me the crank length issue has more to do with flexibility at the hip joint than anything else. After I broke my hip (actually my femur), I started experimenting with shorter cranks. The sweet spot for me is 165 mm. Longer than that makes my leg bend awkwardly and shorter feels choppy when I pedal.

I live only about 2 miles from the Katy Trail so I ride on it quite a bit. 2.1 tires are definitely overkill for the Katy.

I'm in the process of re-doing a 90's era mountain bike for a gravel grinder to be used on the Katy and similar trails. It's going to have 1.75 semi-slicks and I think those are on the overkill side. My reason for using the 1.75 tires is because I think that 1.5 and smaller tires look goofy on a fat tubed mountain bike.

My personal thoughts on the last few posts: Regarding your tires, I agree the raised center can help on pavement. On the Katy that won't matter one way or the other. Off hand I'd say your tires are fine (good) for this trip. I also agree about the chain catcher -can't hurt, may help a lot. If you're not sure about installing it or what it is, a shop can easily help. Brad (above) is also right about smallest cog. You may never use it, certainly not on the big ring, but may on the middle occasionally. Anyway, you have 9 more, which is plenty. Again, my opinion here, but I'd stick with the 175 mm cranks. On a loaded bike you like to have the leverage of longer cranks. Loaded touring is steady cruising, not high performance riding - i.e. "lower" cadences are fine, even good. When I say lower, your 80-85 rpm range is good. I don't think you need to "cruise" on a tour at higher cadences. (This is once again subjective - some riders will hold much higher cadences, but many don't.) Regarding myself, on a tour like this I'd normally range from the upper 70's to the mid/upper 80's. On rougher pavement, uphills and against headwinds I'd shift down and hold a higher cadence (into the 90's), but downhills and good tailwinds, when I don't need to apply much power, I'll sometimes go to that big chainring and a little rear cog and, for a little while at least, really drop my cadence low - basically keeping both the bike and my legs moving, but resting them, not using the effort to hold a higher cadence.

No one has mentioned the chain wrap capacity of the rear derailleur. Currently it needs 22+25 = 47T. I suspect that the stock RD "officialy" has a 45T capacity that is already being exceeded.

Changing just the small chainring to a 22 would add another 4. 51T sounds like a lot of capacity, doesn't it?

Thank you to everyone who has offered advice. I just ordered the triple for under $130, with free shipping. I think that I will be able to spread my riding much better between the 30 and 40t rings--now I ride almost exclusively on the 36t unless I gear down for a hill. I ordered it with 170mm crank (actually, the only option at the cheapest seller), and if I don't like it I think that I can switch crank arms, right?

BTW, I also just ordered my first clipless pedal. I think that it will finally make sense for me to do a fitting. (I already changed the stock WTB plastic saddle for a leather Gilles Berthoud, which made a dramatic difference "down under." LOL)