Please help me spec the right components for this build:

I wanna build a 1x9 road bike with 11-34 gearing. I don't have any of the parts for this bike yet. It's gonna be used for centuries and light touring, and I weigh 150 lbs. I can get an Ultegra hubs Mavic Open Pro rims 32 spokes (15/14 gauge) wheelset for $250 new (a good deal? - I am open to other wheelsets if you know of something better). Plan to use a Deore XT 11-34 cassette. Oh yeah, the frame will be a 58 cm Soma Smoothie ES (chainstay = 430 mm).

So is this enough information to know the chainline exactly? And therefore specify the bottom bracket and crank? Or do I need to have the rear wheel built and physically sitting in the frame and actually measure it to be able to know it exactly?

If so, please recommend a bottom bracket, crank, and chainring, if you like. I'm was thinking a Surly stainless steel ring, 'cuz I heard those are good. 38T or 40T, something like that. I like a 175 mm crank.

Thanks.

250 for the wheels sounds pretty good

just be sure you use a 9 speed chain. and a '3/32' chainring thats the right bolt pattern for your cranks

other than that the just buy whatever bottom bracket is going to fit in your frame. you can get pretty much any crankset, just make sure you run your front chainring where the 'middle' ring would be so its centered with the cassette. also be sure to have single speed chainring bolts or have the washers so you can use other size ones.

shimano 105 crankset would be pretty good imo

1x9, 11-34.....

1x9 is pretty wide. Your chain's going to be at a pretty big angle in the extreme gears in any case, so it's pointless to lose sleep over chainline.

If you really want to be sure and aren't in a hurry to get the bike done, buy the wheels/cassette, install them in the frame, and measure the chainline (to the 5th cog) with a ruler or caliper. Then buy the BB/crankset with this figure in mind.

Theoretically, the choice of hub and cassette should unambiguously determine the chainline, but I haven't ever seen published chainline specs for a cluster before (to the extent that the concept is even meaningful).

Best of luck.

Why do you want to run a 1x9? why not a 2x5, or 2x6?

Not trying to flame, just curious.

+1

Double cranksets look sweet, and keeping the cluster to <9 speeds lets you use cheaper, sturdier chains.

Maybe you're trying to avoid the front derailer?

Cheaper, yes, but sturdier? Do you have any evidence of that? The manufacturers all seem to be claiming that their latest chains, while thinner, are even stronger than their older, wider chains.

He should still try to get the chainring as centered on the cassette as possible. I was using a 3 x 9 setup, but I had no problems using the whole cassette with my middle chainring (42 tooth on a 52/42/30). Unless he'll be riding all hills with no flats, he'll spend most of his time in the middle of the cassette anyway assuming he picks an appropriate chainring (my vote is for a 42).

I run EXACTLY the setup that you are talking about. XT cassette (11-34t), short cage XT rear derailer, Ultegra tripple crank with the inside ring removed and the outside ring replaced with a Salsa crossing guard. I run a 39T salsa chainring with no ramps. I think this is important, people that have ramped chainrings complain about dropped chains.

I used my triple crank because I already had one. I don't know how to calculate your chain line with any given crank (although some manufacturers spec that). I hypothesize that you could use a cheap 1 speed crank (maybe a sungino) and be fine. You can always adjust the chain line for super cheap with a Shimano UN26 bottom bracket ($12 by my house).

EDIT- And for the nay-sayers, I love the simplicity of 1x9. No FD to futz with, adjust, trim, cuss at, etc. And I have 9 gears that are predictably spaced. I never have to remember to downshift n gears on the back because I upshifted 1 on the front. Oh yea, and 9 is plenty for me to get 30-96 gear inches, which is all I ever need.

I'll save the OP a theory vs. practice flame war and just answer you:

Nope, not a shred.

I like your honesty. All I have are (dubious) manufacturer's claims (as if they'd ever admit to downgrading something).

Anyone ever read about an independent test of chain strength? I used to have access to an Instron and it would have been a fun (though expensive) test to perform. I'd have to beg for that favor now though if someone was willing to donate chains to me, I'd try my hardest

How wide is a 9 speed chain anyway? If you get a single chainring crank, it'll take either a 1/8" or 3/32" chain.

Yes, the whole point is to get rid of the front derailer.

Tabor, did you include the Salsa bash guard to avoid chain drop or just to put something in the place of the missing chainring? Or both? The Salsa bash guard sure looks cool.

Also Tabor, which XT rear derailer did you decide to use? I read on Sheldon Brown webpage somewhere that a low-normal would work better with a bar end shifter, which is what I want to use. I dont understand why it would matter, though.

Is it your Surly Pacer that's set up as a 1x9? If so, that's good new for me, since my chainstay will be 1.5 cm longer, which should reduce the cross chaining problem just ever so slightly.

So I can buy everything, including whatever crank I want, except for the bottom bracket. And then adjust the chainline as close as possible with the bottom bracket with the correct spindle length. Is this correct?

Your guess is correct. I mainly got the Salsa crossing guard to replace the outside chainring. This let me use the crank I had in the way it was designed to be used. I am sure you could work something else out, I am just short on free time. Running a single speed crank without a crossing guard would reduce rotating mass. Just be careful you don't get a track crank with a 144mm BCD, because that wouldn't let you run a ring smaller than 45t. Be warned you MIGHT have trouble with chain drop without the crossing guard... but I don't *think* you will... but my advice is worth what you paid for it .

I got the low normal, but mainly because I found one on clearance. I run one downtube shifter, FWIW. I can't complain about the low normal RD, I actually find the construction to be superior to the Ultegra derailer it replaced.

My Surly Pacer is my only bike right now. It is 1x9 and I am loving it. It used to be 3x9 with Ultegra brifters and I PREFER 1x9 with a downtube shifter. You can fine tune your front chain ring choice so that most of the time you are running a pretty straight chain line. But really, when I ran 3x9 I never worried about my chainline when I was on the middle ring.

Just to give you an idea, these are the gears I have. I run 700x28c:

94.9 - There is one hill I know of where I could theoretically spin this out... but I haven't been down that hill since I changed up my drivetrain. But at 120rpm I would be going north of 36mph, so who cares?
80.3 - very infrequent use
69.6 - The is the tallest gear I normally use. I use it at least once every day.
61.4 - This gear too I use frequently, I cruise in this gear a lot of the time.
52.2 - This is my default gear, the gear I am in when cruising through my neighborhood or coming to a stop light.
45.4 - I use this gear frequently up hills.
40.1 - very infrequent use
34.8 - very infrequent use
30.7 - This is my bailout gear. I use it to get up a hill on my way home from work. I also have it there for when I am towing my trailer.

I don't see why you couldn't buy all your parts except the BB, but I am not a professional bike mechanic.

EDIT - PS- I spin like a mofo.

Tabor,

It's interesting to read your list of 9 gears and how often you use them and what for. It sounds weird that you have gears in the MIDDLE that you use very infrequently (2nd highest, 3rd lowest, 2nd lowest). I guess it makes sense if you're describing a specific ride that you do every day, such as your commute. But if I'm riding a bunch of different rides with a lot of varying terrain, I think I would use that entire continuum, without being able to predict which gears I don't need.

From the numbers it looks like you're using either a 38T or 39T front chainring. Which is it? Where do you live? What's the terrain like? I ride in the SF Bay Area, and it's very hilly.

Why did you choose a downtube shifter instead of a bar end? I had a cheap Fuji downtube shifter bike once and it seemed really annoying to have to reach down so far every time to shift. A bar end is right there. It doesn't bother you? Then again I really like riding upright and I'm on the flat part of the bar almost all the time.

1. Yeah, I will definitely get either 130 or 110 BCD for this 1x9. Does is make any difference which size? It seems like a very wide range of chainrings are available in both sizes. If I someday want to switch it to a road double, I think I wouldn't use a larger ring than 48T.

2. What is the difference between a single speed crank and a road double? Chainrings can be mounted on both sides of either type of crank, correct? So physically aren't they exactly the same?

3. So once I have my rear hub and cassette, I'll know my chainline exactly. So then it comes down to chainline adjustability. I know I can buy a square-taper bottom bracket with the correct spindle length. But what if I choose an outboard bearing bottom bracket? It seems like the industry is switching to these, and the consensus seems that they're actually better. How do I adjust the chainline with this type of bottom bracket? It doesn't have any spindle that protrudes from the bottom bracket.

4. Finally, I'd like to have the option to someday switch it all to a double crankset. In case, for some reason, I hate the 1x9 setup. What type of crank should I choose to make sure I can do this? And doesn't this mean I would need to adjust my chainline a little bit, going from one chainring to two? What's the best way to do that?

Thanks VERY MUCH!

The advantage to using a 110 BCD is if/when you converted to a double, you have more choices of chainrings than if you chose 130. 130 BCD will only allow a minimum 38 tooth chainring whereas 110 will allow you to run a 34.

The difference is in the chainline and spider. Chainline is really only a concern with integrated spindle cranks as their chainline is not adjustable (unless you are running a MTB crank intended for a 73mm BB shell in a 68mm shell, in which case you have some adjustability). If you are comparing square taper cranks, there are enough bottom bracket choices around that you'll be able to get a perfect chainline with either crank regardless of how it was intended to be installed.

The spider of a double crank is designed to have a chainring mounted on the backside whereas a single speed crank is not. If you want to run only a single chainring on a double crankset, you'll need special chainring bolts as the stock ones will be too long with only one chainring.

As I mentioned earlier, the outboard bearing BBs do not allow for chainline adjustment in most cases. You can only get away with shimming when you are intentionally using a too-long spindle for your BB shell. You'll have to use a crank intended for offroad usage though.

https://www.sheldonbrown.com/gloss_ch.html#chainline

If you read at that link, you'll see that the ideal chainline measurement for your application is going to be between 43.5 and 45 (double and triple chainline specs respectively). If you are using a track/singlespeed crankset intended for a 120mm spaced frame, take the manufacturer's recommended spindle length and add 3-6mm (verify that the spindle you have chosen is symmetrical first). This should center you on the cassette.

You will want to choose either a double or triple crankset if you want the ability to add an inner ring some day. You have a few options for the "easiest" way to make this happen though all are some sort of compromise.

1. Buy a new bottom bracket to adjust your chainline when you add the new ring

2. Use a road double crank and use the normally recommended bottom bracket. This will put the outer chainring out a little further than optimal but plenty of people use the big/big combos on their doubles without issue so you should be ok. Adding the inner ring will be just that simple.

3. Use a road triple and use the normally recommended bottom bracket. Your single chainring mounted on the inside of the spider will be very close to centered on the cassette. When you add the big ring, you won't be able to use the last one or two cogs on the casette without some noise but that's no huge loss. You can also add a granny ring if you'd like.

nauboone,

It surprised me too when I found there were low gears I seldom used. I live on the East side of Portland, OR. FWIW, I used to live on the (very hilly) west side and the 30 gear inches I have now matches the 30 lowest gear in my triple setup. I am running a 39T chainring.

I chose the downtube shifter because I vacillated a long time about how to run bullhorns with reverse levers in the ends of the bars. I had a few choices but one day I was riding along adjusting my FD by fiddling with the barrel adjuster located on my DT braze ons... then it hit me. If that was fine, shifting downtube shifters would be fine too. I am not going to argue they are as convenient as they would be on the bars, just that it doesn't bother me.

As joejack951 has mentioned, one of the easiest and most versatile setups would be to buy a triple crank and set it up the way I have. The chainline is already taken care of for you by the manufacturer, and you can always switch to a double/tripple setup later. joejack951 is correct when he states that 38T is the smallest chainring you can fit on 130BCD, but road triple have the inner ring on 74 BCD if my memory serves. Also, rumor has it that some road cranks don't accept chainrings smaller than 39T. However, I am a little disheartened by road groups, I would go with a MTB crank if I were you. That would let you run 26/36/48 or something similar if you ever wanted to. It is pretty common for touring bikes to have "mountain bike" components. I think shimano fails at marketing in this regard.

joejack951, You don't have a Porsche 944 Turbo, do you? Just curious.

EDIT- But be careful because a mountain crankset with suggested BB for a mountain bike with 135mm rear spacing will have a slightly wider chain line than a road crank by ~5mm... I think. Someone can correct me if I am wrong. Some cranks have suggested BBs for road and mountain listed separately because as I stated before it is normal to run mountain components on road bikes for touring. However, some touring bikes take care of this pseudo-problem by adopting 135mm rear spacing.

I just wanted to add that everything written here is correct. However, a lot of the cheaper single speed cranks are NOT designed for true 120mm track frames but are instead intended (as far as I can tell from reading the specs) for 130mm conversion/IGH hub applications. So, don't assume that a crank is intended for 120mm spacing without carefully scrutinizing the specs.

Not spec'd for a road chainline, but I run a 1X9 on an MTB set up for dirt/fire roads without problem. Crankset is a SS 32 with bashguard on the outside. Just for a little extra peace of mind I have an inexpensive Blakspire "stinger" chain keeper installed. There have been no wear or chain jumping problems.

The SS chainring is set up right on my 5th cog. If all else is equal this would be expected as it occupies the place that the middle ring would on a triple. I'm using an Isis drive 113mm bottom bracket so I expect that you might be able to use a similar crankset with a 108mm BB on a road frame.

Yes I do, though I don't really drive it at all these days (need to make up my mind to either find excuses to drive it or sell it). I know Dannoxyz used to own one as well and likely still does.

Good point. Not being a singlespeed guy, I'm unaware of all the mutations that have sprung up as solutions for unconventional single chainring applications.

Ok, I did some research and came up with this 110 mm BCD road double crank:

The Sugino Swiss Cross, which has 34-48 chainrings. I like that gearing. Most other road doubles use 36-50 or 39-53 (way too high!) I can only find it for sale here: https://store.somafab.com/suswcrdocr.html, for $120. With this crank, I would remove the 48T chainring, and replace the 34T chainring with a 38T or 39T single speed chainring. Sound like a deal? Anyone know of a better value road double crankset with similar gearing?

The only issue then is whether the square taper interface is a good idea. I know I can get the chainline perfect using square taper because the bottom brackets are available in so many spindle lengths (and they're cheap). But is this NOT true of Octalink and ISIS? These bottom brackets are NOT available in many spindle lengths?

There is one other issue: I will need to remove the cranks on a regular basis, since I'll be packing this bike into an S&S suitcase for travel. Are the square taper cranks hard to remove and reinstall? Would using Octalink or ISIS make this step any easier?

Thanks.