ok so round my way is pretty flat and i do spend most of my time in the middle ring.the range on the block of my 9speed set up is again spot on so..
im thinking of building up a new bike and thought 1×9 made sense.essetially taking away the gears i rarely use.as im building this from scratch i will need a chainset and wondered what most people use? is it cheaper to use a common triple set up with just the middle ring or buy a specific single ring chainset.im thinking single is uncommon/downhill/hiche so they arent to cheap?i havent researched prices yet tho…
also why is some kind of chain devise needed? you dont need them on a 27 speed set up??
would the rear deralier etc all be the same/compatable?

Chain device – you don't need them on a 3 ring set-up because if you're in the middle ring the worst that can happen if the chain bumps around and skips is that it will either bump back off the large ring or drop into the granny (assuming the derailleur doesn't catch it first)

Whereas on a single front it will just drop.

Doesn't happen so much on ss even with a chain tensioner because the tension is that much higher, whereas for an 11-32 or 11-34 setup the derailleur has to cope with quite a wide range of tensions

In addition to the excellent comments by the otherjon:

The only reason you might want to consider a single ring specific crankset is if you're planning on using a full (i.e. top and bottom) chain device. Sometimes (but not always) the mounting for the granny ring on regular triple chainsets interferes with the back plate of the chain device. It depends on how the chain device is mounted of course. DH cranks tend to have removeable granny ring mounting bolts, e.g. Race Face Diablous/Atlas FR etc or they don't have them at all, e.g. Shimano Saint in order to alleviate the issue.

In reality you're unlikely to need a full blown chain device unless you're really gunning it, and many of the single top guides you can now buy for 1×9, such as the MRP 1×9 and the new e13 device present less of a problem although you can still have issues.

These devices also tend to mount behind the BB cup, so even if you don't have ISCG tabs you can still use them.

the front mech kind of does the job of most xc type chain retainers, you will notice what a good job it does if you try to ride anything rocky without using a retainer. if you want something more robust look at an e13 lg1+ or similar, with this you can also still run a 32t front ring and you dont need iscg tabs as it comes with an adaptor.

the rear mech, cassette and chain will all be fine, make sure you use a front ring that is the correct diameter for your chain though, dont buy a bmx one or anything.

the crank thing is down to personal choice really, either is fine. some brands such as raceface sell the crnks without rings which will save you a bit of cash but you can always flog new chainrings on the classifieds.

good luck!

"ISCG tabs "

woz dat den??

Run everything as standard as your 27 speed setup but it is worthwhile getting a ss chainring and a chain device of some kind, or you can run your front mech to try and stop the chain coming off but that never works as well as a proper chain device.

I'm tempted for this as well – any experience of anyone using a bashguard to cope with throwing out and a dogfang thingy to cope with the in?

Oh and Superstar do a pretty good chain device that won't cost the earth, fits easily onto external bearing bottom brackets.
ISCG mounts allow you to bolt things like chain devices directly to the frame rather than just an adaptor and onto the bottom bracket.

cant see why it wouldnt work but id be tempted to run a stinger or similar to wrap the chain that bit further around the front ring.

my lg1+ has been absolutley faultless down stuff thats always had my chain off even using a stinger. weighs less than most bash guards too!

what if i didnt have an external bb? how would/could the divise mount?

BB mounted devices work with both external and traditional ISIS/Square Taper bottom brackets.

what geetee said, the device just sits on the threads of your bb and is trapped between the frame and the outside edge of the bb.

I ran 1×9 for quite a while without a full on chain device, with very few problems. I had a single ring, on an old XT triple chainset. I took off the granny ring and replaced the outer ring with a bashguard. As well as the bash, I used one of these. Granted, it's not rocky where I ride, but I never had any issues with losing the chain.

I used a normal long cage rear mech, but have heard people say that a short cage mech would be better, as you can run them with slightly more chain tension. Don't know about that for certain though.

short cage mech would be better

medium cage really. short cage mechs really dont like 32T cassettes. as i found to my dismay – ater telling everyone on here how well it worked – then my casette ate my mech! 🙁

If you have a cartridge type BB, strictly you'd need a different width (E-type specific) to allow for the 2.5mm (iirc) width of the mounting plate. External BB's get around this with the 3 spacers that you add / take out depending on your BB size, one of those takes up the same slack

However – as long as you still have enough thread on the BB to get properly deep into the BB shell it would probably be OK to use your existing one – the other supposed downside would be chainline but as you're on a 1×9 setup anyway that's probably of little consequence in reality

I'm currently building a 1×9 Swift and have been looking at different chain guide options over the weekend. Pauls Components have a rathr nice looking chain guide system which mounts like a front mech on to the seat tube (Jenson USA are out of stock of these at the moment 🙄 ). Also E-13 have just released a new XC style chain guide called an XCX but I'll be buggered if i can find one of those anywhere 🙁 . MRP do a similar system although it look a bit too downhilly for my nice new frame.

Just thought i would offer these as alternatives as they are also alot cheaper than some of the full on chain guides if your just doing XC stuff 😕

I ran 1×9 for a couple of years, used the n gear jump stop and a bash, tried unrampped rings etc but still dropped the chain without anything to guide it, the MRP 1×9 thing looks just the ticket now.

1×9 Its all very well if you just build a bike for local trails, but if you got the one bike it doesnt make any sense, now I am down to 1 bike its got the full compliment of gears on it, makes diddly squat difference to weight and most of the time it lives in the middle ring, but its nice having a big gear for road and little one for days when I just fancy twiddling up stuff.

makes diddly squat difference to weight

my xt shifter, front mech, cable, granny ring and bash ring came to just over 500g, so over a pound. and my chain wouldnt stay on down rocky stuff. horses for courses innit?

I did it, didnt weigh the 2 for difference, but would be very supprised if it added up to 1lb difference… Still I stick by my comments its not worth the saving especially if its your 1 bike, I did a reasonably hilly (chilterns) 100k offroad sportive on mine but there was times when I really fancied the luxury of a granny ring to drop into, then there was the race I dropped the chain 13 times in 1 hour 20 min ride around Lotts Wood, ordered the jump stop and bash the next day. do it you fancy a quick dabble at niche stuff..

Here it is, I was just dabbling with an unrampped front chainring after reading lots of poo on here about it keeping the chain on better. It didnt.

A couple of other minor points to add would be to factor in some short chainring bolts for nipping up the middle ring. Unless you are riding really rocky stuff and NEED a bash, just run a chain catcher, or a extra tensioner. MRP do some nice ones, as do e-13.

Another thing to consider is that sticking a bash guard on does add to the rotational mass of the bikes, whereas the new devices just have a 'taco' type guard static underneath the chainring. Not only is this lighter, but its easier to spin the pedals with less weight on them.

FWIW I've just fitted a MRP Mini-G2 to my BFe, as I really liked the system and I tend to bash things pretty regularly, especially on the hardtail. Without a chain device I would regularly get halfway down a descent and try to pedal a few strokes only to find I've dropped the chain, so end up freewheeling down the last of the descent – RUUUUBBBISH!

would be very supprised if it added up to 1lb difference

got me doubting it too so i went and weighed all the gubbins i took off. 510g.

Is it just me or does the MRP 1.x device seem bizarrely expensive at £40? I mean, it doesn't move or anything, and a front mech is cheaper.

Front mechs might be cheaper but they don't keep the chain on 100%; I've tried this myself and while a front mech does reduce the problem, on a 2 hour ride I still dropped the chain about half a dozen times.

got me doubting it too so i went and weighed all the gubbins i took off. 510g.

I am def supprised by that, did you weigh the stuff you added to keep the chain on? Still a 1lb saving is looking on the cards.

yeah i did, the lg1+ was 200g all in. but those top only chain guides obviously weigh less so thought the weight of the bits you take off would be more useful to know. either way even after fitting aguide its still a good amount.

i used to use a modified rohloff chain guide, about the lightest most reliable thing i could come up with, used to work very well. i'm using ss or 2×9 at the moment

"Is it just me or does the MRP 1.x device seem bizarrely expensive at £40?"
Yes, me too, but what else are you going to buy? They'll charge what they think they can get
CRC have them for £37
A Rohloff guide is £43 (+P&P)

I'm just finishing building my bike running 1×9 (just been out on it for the 2nd test ride 🙂 ). Decided to do it for the same reason as you, its flat as a pancake round here and I found myself sitting in the middle or big ring and just flicking through the rear cassette.

Built mine up with mostly 2nd hand bits from here/eBay and a few new bits thrown in aswell. Running a 36T single front ring on normal triple chainset with short bolts instead of the normal ones. I use a 11-34T rear cassette, 9 speed chain and a short cage X0 mech with an X0 trigger shifter. Not got a chain guide as of yet, has been running fine and the chain hasn't popped off, but got a Paul Components Chain Keeper on order from here, which should be here by wednesday. Company is in the UK and it's cheaper than the MRP too – comes to £35 posted.

More pictures. Still got Eggbeaters and the chain guide to go on, but pretty much done…

Another thing to consider is that sticking a bash guard on does add to the rotational mass of the bikes, whereas the new devices just have a 'taco' type guard static underneath the chainring. Not only is this lighter, but its easier to spin the pedals with less weight on them.

seriously?!
in the real world, do you really notice this!?
😯
i'd say the smoothness/standard/condition of the BB would have a far greater effect, and when riding with shitty BBs i've never actually noticed it when riding…

Pauls one looks good doesnt it… 🙂

Despite reverting back to the full hit myself, 1×9 does look nice doesnt it. Maybe I need 2 bikes again!

Up till recently i used an E13 guide ring chainring, and having a chain as short as possible, and didn't need a chain device. No chain dropoffs at all.

Recently started using a rotor chainring, and as its ramped I've started using the Rohloff guide with good results.

The Pauls guide is very nice, but wasn't compatible with my FS frame.

"Is it just me or does the MRP 1.x device seem bizarrely expensive at £40?"
Yes, me too, but what else are you going to buy? They'll charge what they think they can get

I know, and agree. Maybe when e13 get theirs in the shops we might see prices drop? Probably not… The other PITA is that medium cage mechs seem to cost about £10 more than long cage.

I run SLX cranks just using the middle ring. medium cage mech. 11-32 cassette. bash guard and N-gear jump stop.

works faultlessly, never dropped the chain.

Kev

this is a bit cheaper, £25.

if its a problem with spending cash, why not just leave your front mech on and use the stops to set it where you want it? if you cant get it there with the stops alone you could always run a short section of cable to the nearest cable boss and put tension on the mech that way. it might look fugly but it would work.

At the moment i'm using the front mech with the limit screw maxed out, luckly I can get it to sit in just the right place. I am going to grudgingly buy a proper chain-guide at Christmas.

Have just posted another thread on this topic as didn't see this one but will move it over here. Here were my questions – plus my responses from reading this thread in caps:

1. Do I run a standard cassette on the back? Up to 34T? – YES 11-34 WILL BE FINE
2. Do I run a standard chain? – YES
3. What size chainring do you run on the front – can I run somewhere in between 22/32 teeth? – NOT SURE
4. Do I need any special cranks / chainring? – DON'T THINK I HAVE TO BUT ADDING A CHAIN GUIDE WOULD BE BENEFICIAL
5. Can I run a short cage rear mech? YES BUT MEDIUM CAGE WOULD BE BETTER
6. Do I need an external BB? PROBABLY BEST
7. Anything else to bear in mind? I'M BUILDING UP A 29ER – POSTER ON THE OTHER THREAD SAID THIS MAY AFFECT THINGS…

Any advice greatly received.

@rockitman

3. Typically 32 teeth would give a useable range of gears. If you find the gearing a bit easy/low you can always try a 34 or 36 tooth. You need to be able to fit the chainring on the middle of the crank for the best chainline, and I suspect 22 teeth wouldn't work.

4. No special cranks required (I use Shimano LX). You will need short chainring bolts if you use a single ring with no bashguard. You will need some sort of device to stop the chain falling off, like an XC chainguard (i.e. MRP 1.X) or a bodged front mech.

5. Some people say a short cage mech will foul the cassette – I think short cage mechs are designed for road cassettes which have smaller ranges. Medium would be ideal, but you can still do it with long. Just doesn't look quite as nice.

6. Not sure that it matters.

7. The fact that you are building a 29er might affect your gearing slightly. Since your wheels are a bit bigger the same gear will feel higher/more difficult than on a 26er. I would suggest using a 32 ring up front and 34 cassette out back. If you find it too easy you can up to a 34/36. You can probably buy a 30 ring somewhere if it's too difficult.

Thanks Poppa.

My concern is that it will be too difficult. I usually ride on the middle/granny. Very rarely use the big ring but then most of my riding is in the peaks. I'm building the bike for solos at Mayhem and SITS / Kielder 100. I rode Llandegla on the middle ring on Sunday to see how I'd cope and it was fine, made it all the way round the red/black. Mayhem & SITS are no tougher and I believe the 100 is quite a lot of fire road.

If I could do Front 28 + Rear 34/11 that might be perfect on the 29er.

i dont know of any middle rings less than 32t though i may be wrong. i wouldnt want to try and get a decent chain line if i had to mount a ring in the granny position. though thinking about it, if you had a 68mm bb shell and got a seat tube mounted guide rather than a bb one you could put all 3 spacers over on the drive side of the bb and that would shift it over 2.5mm, not sure if that would be enough though. maybe running a square taper setup and offsetting it to the driveside would work?

you might want this 12-36 cassette for 29'rs, if your doing big rides the lower gearing will be a bonus, or just keep the triple up front.
http://www.chainreactioncycles.com/Models.aspx?ModelID=31059