I’ve recently built up a singlespeed, following on from some good advice given to me on this site. When I took it for the first ride it was great, but I experienced slipping somewhere in the drivetrain when under heavy pedalling loads (steep-ish inclines etc). I put this down to using an old chainring and chain with a new sprocket, so ordered an On-One chainring and new nine speed chain. Annoyingly, the problem still persists. I am using the aforementioned chainring and chain, and Superstar rear sprocket and tensioner (32t and 16t). I think the problem may be chain wrap, although I definitely have the chain as short as it will go. If I take out one more link it is impossible to get the rear wheel into the drop outs. I was wondering if this would do the trick, and possibly enable me to ditch the tensioner to increase chain wrap?
http://www.chainreactioncycles.com/Models.aspx?ModelID=57323&utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom

I am assuming that it must be slipping on the sprocket due to chain wrap being inadequate, and not due to dodgy Superstar Sprocket or tensioner (basic but seems okay). I am not losing the chain at all, and am pretty certain the chainline is close as possible to perfect. Any opinions gratefully received!

Not having enough chain wrap around the rear sprocker can be an issue. Also the basic spring operated tensioners don’t tend to work well if there’s too much slack in the chain as the spring unwinds too much and doesn’t provide enough tension.

A half-link chain may help as would a different set of chainring and sprocket e.g. switching to a 34t:17t or 36t:18t. If your chain is too slack by almost one link (i.e. one inner link and one outer link) then a 34t:17t might work. If it’s too slack by just over one half-link (i.e. one inner link or one outer link) then a 36t:18t might work.

Here are some basic pics. The tensioner doesn’t have much more room to move as it is fairly stretched as it is. I just want to make sure that I buy the right thing – even if a better tensioner is the way forward.

One thing I have noticed, is that the arm of the tensioner seems to “oscillate” slightly up and down when the chain is moving through it, almost like the tension is varying. It’s not by much but is noticeable, is this normal?

It’s that tensioner. Ditch that and do it properly

It’s not enough chain wrap.
The tensioner can be modded to push up, but I found it a bit hit and miss. I’ve got a Gusset push up tensioner you can have for £8 posted – (I bought it almost unused from here, then remembered it won’t sit on cowled dropouts)
I now run 32:18 (hilly in the Lakes) and a posh Surly tensioner – 16t did exactly the same with me as you describe.

First of all I would not use a 9 speed chain as they are more expensive than a 8 speed chain or a 1/8″ chain.

The problem you have is chain tension. BB mounted tenioners have sorted this problem more me in past but in the end even that failed as it required regular adjustment to account for chain wear. Also after a few years of regular adjusment (the pulley was right up aginst my bash guard so I could not move that) one the threads in the frame frame failed so I binned that tensioner have have gone tensionerless. I do have to replace the chain a bit more regularly but KMC Z510 chain is pretty cheap so is hardly an issue for me. However that could be a pain for others.

A different tenioner or solutions that Sun have already stated are the one I would start with. It will require a bit of experimentation.

The problem I would have with a push-up tensioner is that I think it would push the chain into the stays. Not sure how I could adjust my chain line to bring the sprocket inboard a bit (could I lose the spacers at the bottom bracket as it’s singlespeed??) I wouldn’t mind running a slightly larger rear sprocket, say an 18t as that would be better around the Malverns, although I think not so great for the more general riding I tend to do (FOD etc) I guess.

The chain wrap isn’t ideal but not as bad as I was expecting. Is the Superstar sprocket meant to be used with a 9spd chain. The ones I have are meant to be used with 1/8th or 3/32nd chains.

One thing I have noticed, is that the arm of the tensioner seems to “oscillate” slightly up and down when the chain is moving through it, almost like the tension is varying. It’s not by much but is noticeable, is this normal?

Yes, it’s because the chainring isn’t perfectly concentric as there will be some tolerance in the chainring bolt holes.

bm0p700f, is the chain you’re using a half link?

http://superstar.tibolts.co.uk/product_info.php?cPath=58&products_id=266

Sum, it doesn’t seem to indicate which chain width…

http://superstar.tibolts.co.uk/product_info.php?cPath=58&products_id=480

Just noticed this too. Would this likely improve things? It appears they have added some new products since I ordered my stuff 2 weeks back!

you can get an alternative spring to change the tensioner to push up from a few places – eg charlie the bikemonger.

I converted my Merlin just like you but used the KMC chain mentioned above:

*On One chainring
*Superstar wide base 16T sprocket
*KMC singlespeed 3/32″ chain with masterlink
*KMC half link to get the chain as short as possible (from Charlie TBM)
*Cheap tensioner converted with a Surly push up spring and with the pin to rest on the derailleur hanger stop removed to enable me to tension it to push up.

The push up tensioner attaches to the mech hanger – it won’t get near the stays.

Mokl, you’re right, it’s doesn’t specify what chain can be used with the Singlestar sprocket Looking at the reviews for the wide based sprocket on it’s own, I noticed there’s a couple of complaints about the sprocket being slightly elliptical, which may also explain your chain oscillating.

Edit: Check your sprocket carefully. If you think it’s ok, get the half-link, if not buy a new sprocket from Charlie the Bikemonger. If you do the latter, think about chosing a chainring/sprocket that would be a ‘magic ratio’ for your frame.

boxelder – because of the amount of chain slack, I can push the chain into the stays. I tried removing the spring from the tensioner and using it as a push-up to see if it would theoretically work.

Would an eliptical sprocket possibly cause the skipping, Sum? It does seem to occur at a consistent point in the pedal cycle path (I put this down to leverage though).

Just read the sprocket reviews. Sounds a tad dicey. Won’t be able to check it until tomorrow, but will update with my findings!

Just managed to go and have a quick look. Eyeballing it, the sprocket does appear to be slightly off. What a pile of poo.

http://www.charliethebikemonger.com/gusset-doublesix-ss-cog—wide-foot-212-p.asp

I might try this in a 17t as a compromise – any thoughts?

maybe this: http://www.charliethebikemonger.com/wtb-laserdisc-single-duty-single-speed-cog-1452-p.asp

?

On one do one too don’t they?

edit@ that’s for an 1/8th chain. might be too fat. Maybe try calling/emailing charlie.

Would an eliptical sprocket possibly cause the skipping, Sum? It does seem to occur at a consistent point in the pedal cycle path

Usually tightspots occur when the chainring isn’t perfectly concentric but an elliptical sprocket will also cause this as well.

I’d use an on-one SS cog and a half link chain – you won’t need a tensioner then.

the chainring eccentricity will have more of an effect normally. tbh I’ve not noticed my SS sprocket to have any eccentricity. The advantage with sprung tensioners is that they cope with small deviations unlike horizontal drop outs.

You don’t need a full half link chain. I just fitted a single KMC half link to a KMC single speed chain to get my chainline almost perfect. I may have got away without the tensioner bus used it anyway and never had any slipping.

Okay, I’ll try the chain first to improve the tension, then invest in a new sprocket if it still slips.

Sory for the slight hijack but I’m in need of a need for a new SS chain, what half link chain?

I have the same problem as the OP but am already running a similar tensioner and a half link chain. I like the look of the BB mounted tensioners, where can I get one from? I’m seriously considering getting a SS specific frame!

I was just going to try one of these if my sprung tensioner didn’t work: http://superstar.tibolts.co.uk/product_info.php?cPath=56&products_id=336

Someone was selling a wide base 16T sprocket in the classifieds yesterday.

For chain I use one of these: http://www.charliethebikemonger.com/kmc-z610-hx-chain-332-41-p.asp

with one of these: http://www.charliethebikemonger.com/kmc-half-link-279-p.asp

UPDATE!

In the end I ordered a KMC HLC710 chain from On One. I would have gone for the cheaper option and half link, but nowhere seemed to have the half links in stock. Anyway, after a little messing about it is absolutely perfect, and I can ditch the chain tensioner. I didn’t think the wheel was going to sit all the way into the dropouts once I’d fitted the chain, but it went in perfectly – almost like it was designed to go in there. Needless to say it is now skip free, and I am very pleased. Many thanks to you all for the advice and for helping to salvage my sanity. Here is a quick pic. It is a fairly basic spec as it was constructed mainly from spare parts (apart from the drivetrain, ironically…) but it rides lovely. Note the retro X-lite bar plugs I found lurking in the bottom of a box in the shed.

That’s a Dialled 853 PA (the original version, not the new one) for anyone that cares.

I should also add that it is quite apparent that the Superstar rear cog is slightly elliptical, but there is no eccentricity problem and it seems to work fine now.