I'm thinking of a singlespeed, but due to my wonky knees I need a high 'Q factor' (wide chainline) such as the 54.5 Rohloff that I already have. The question is, are singlspeed hubs available in varying chainlines, can I have the rear sprocket out as far as possible, or are the hubs all built for a narrow chainline.

I appreciate that I'll have to get a long bottom bracket axle to suit, and that I could get a hub spacer kit and juggle the spacer around to suit – or can I?

just use a 9 speed hub, then you can put the sprocket wherever you want to get the best chain line.

q factor and chainline are not neccesarily related though. space the pedals out if needed.

As above, just get a wide chainset (basically all Hollowtech 2s by Shimano) and use a standard 9 speed wheel with spacers to allow you to position the sprocket as required to get the right chainline. Middle ring will roughly equate to the middle of the freehub (slightly out maybe)

I want it to equate to the outer (big) chainring 54.5mm.

I guess spacing the pedals out would have the same affect. Just that getting spd's with extra long spindles would be a problem! And I've spent ages getting pedals to work with my knee probs, Shimano oddly enouogh work out best, imagine what it would be like to get custom spindles from them – impossible!?

I notice King do a variable singlespeed hub if I could afford to go down that route. The spacer kits of 9speed seem a bit limited in terms of getting the spocket out as far as possible, I think they are desingned around the assumption that the middle ring will be used.

IIRC HT2 is 50mm at the middle chainring so the outer must be about 53 or 54 anyway but the chainline is nothing to do with the Q factor – or at least it doesn't have to be, meaning that you can't say that because a chainset has a specific big ring position that it'll definitely have the Q factor you want.

The only alternative that I can think of for wider Q factor is a square taper chainset that is designed for a narrow axle (eg Race Face turbines take a 107 or 110) mated to a wide axle (eg 122).

As for spacing the sprocket on a rear hub, there are all sorts of spacers that work – ones from old cassettes, HT2 BB spacers, even cut down bathroom plastic plumbing tubing.

There is nothing to stop you running it further out with those kits though, and nothing to stop you running the 'middle' ring in the 'big' ring position on a shimmy HTII c/set.

Hope make a nice SS Pro II hub that you can space it to the outside of.

You might want these then… Kneesavers

Thats said, the rohloff chainline is essentially the outer ring position on most cranks, so unless your running your rohloff with the ring in the middle position of your cranks then your not running anything special.

The only Hope SS hub I saw on CRC was a 'trials' one?

I know it can be done with plastic tubes and the like, but I want it nice, no creaks and reliable – being a bit of a perfectionist and all!

SATO, wow! and so simple too. Thanks

I know I'm not running anything 'special' that's just the point, I want to keep the foot spacing as it is, and not go to a narrow spaced singlespeed specific crank width. I should have made that clear, as I intend on running a nice SS Middleburn Uno or WhiteInd Eno which need a wopping 126mm BB axle to get the 54.5 Rohloff chainline. I could just go for the standard SS width and get the 'kneesavers' now. 🙂

The Hope SS hub is this one –
http://www.hopegb.com/voir_rhpr32btr.html
http://www.chainreactioncycles.com/Models.aspx?ModelID=11034

They include it for trials as the cassette area is much shorter than normal so you can have just a 4 speed cassette or whatever.

woodsman, i think you need to tell us what cranks (and bb) you run with your rohloff. Using a crank like the uno and spacing it out with a 126mm bb will make the Q factor VERY wide, unless you also have this setup on your rohloff i think you might be shocked.

(point to note, pick 3 cranks at random and use the same BB will end up with 3 different q-factors. Basically what we are saying is dont choose your q factor by bb length or chainline, as they are different to q-factor for different cranks)

also worth noting that you can space the chainring off the cranks with spacers (check the fixie/singlespeed sites) so chainline dosnt even have to be dictated by the crank.

I'm using Thorn's standard chainset (a double/triple with a single ring) and a UN54 73 113lenth bb.

I can't see that the pedal spacing would be wider, using a Uno spaced out to get the same chainline. As the singlspeed specific cranks tend to be narrower not having the spider, surely it would result in just the discrepency between the cranks and their curve/width?

The crank on the basic Giant Bowery has a huge Q factor -(truly horrible on a fixed road bike) and it may do the job. It is a road spider though.

I'm using Thorn's standard chainset (a double/triple with a single ring) and a UN54 73 113lenth bb.

So basically a normal q-factor (distance between the pedals), i thought you needed a high q-factor? or by high do you mean not narrow (like a road bike)

I can't see that the pedal spacing would be wider, using a Uno spaced out to get the same chainline. As the singlspeed specific cranks tend to be narrower not having the spider,

Most singlespeed cranks have a similar q-factor to normal cranks (as they still have to clear the chainstays on frames) and they are usually derived from nromal cranks, just leaving the granny tabs off and fitting a bash in place of the big ring. The middleburn uno for example uses a normal RS&/8 crank and their uno chainring was manufactured to be a 50mm-ish chainline when paired with a standard bb (again, so they clear chainstays). If you use a set of RS7's with a wider bb (above 113mm) you will prob end up with a q-factor wider than on your thorn, this may/may-not be what you want?

Also, if your happy on the thorn as is dont get those kneesavers! they add 20mm to EACH pedal axle so are more likely to damage your knees if you dont actually need them.

Just to add to what people have said, but chainline and q factor are different and are basically unrelated. Q factor is the gap between the pedals and you can measure the outside of one crank arm at the pedal thread to the outside of the other one to get a measurement for it. Chainline is the distance between the niddle of the chain and the centreline of the bike. You can have many different chainlines for the cranks with the same q factor – e.g. you could run a set of triple cranks and use the middle or outer positions for the chainring. That would give different chainlines but the same q factor. It looks like your crank setup will have a normal mountain bike q factor, so pretty much any singspeed crank set up normally should be about right. Check manufacturer sepcs against your measured q factor to be sure. Standard SS chainline is 52mm which is probably what you'd get if you shifted the chainring to the middle position on your thorn.

what stato said.
space out the chainring off the crank with some washers, and run the chainring further out.

have you tried specialised body geometry shoes?

wouldnt ever go back from them myself.

also, some pedals (times?) have the clip at an angle, so it tilts the foot outwards iirc?

Yep, a normal Q factor not a narrow type is what I require. I thought that if I went for a 50mm chainline USING a Uno on a new singlespeed build, then the Q factor would be more narrow and aggrevate my knees. I understand what you say regarding clearing the chainstays.

Body Geometery stuff is dreadfull for me, they assume everyone has the same shape legs, completely the opposite for me – slightly bandy legged, and Time pedals were killers when I had them. There is lot's of advice out there regarding knee problems in cycling, most of it worked against my ailment. I've got that nailed now,understanding my own body geometery just didn't want to antagonise it by going to a narrow Q factor.

Thanks for the advice.

i thin kyou need to determine what your q factor is. and aim for that – forget the chainline issue for the minute.

info here on measuring your q factor.

if you are not confident in measuring and working out what cranks/ bb will replicate it. find a shop that has a good range of stock and does bikefit/ similar. bikelab in poole are my recomendation if your down south.

just wanted to add you can get washers to space the q factor smaller ammounts than the knee savers – again you need a good bike fit place. cyclefit in london is highly regarded.

Good advice there tt, I shall do exactly that, before worrying to much about chainline.