Yet Another Cycling Forum

General Category => Freewheeling => Velo Fixe => Topic started by: The Solo Socialist on January 11, 2017, 08:05:11 pm

Title: Chain Tension
Post by: The Solo Socialist on January 11, 2017, 08:05:11 pm
New to riding on fixed. So this is probably a simple or stupid question.
However my chain tension slackens very quickly, set up with tension ok, not overtight nor slack. Chain tug fitted, nuts as tight as I can get them! Ride maybe 50-60 ml and chain is loose enough to cause worries of it coming off, retension required
Bike is 1970's Holdsworth, forward facing drop outs, chain tug Surly!
Title: Re: Chain Tension
Post by: fd3 on January 11, 2017, 10:28:30 pm
Check that it is slack for the full rotation, it may vary between slack and tight, which would be based on off-centre chainring.
Title: Re: Chain Tension
Post by: The Solo Socialist on January 11, 2017, 10:52:24 pm
On set up chain set at tight spot and only slightly slack at loosest point. After riding slackest point is really slack.
Chainring set as round as possible as Sheldon Brown! Chainring bolts checked for tightness!
Title: Re: Chain Tension
Post by: mrcharly-YHT on January 12, 2017, 08:27:38 am
What sort of nuts are you using?
Title: Re: Chain Tension
Post by: The Solo Socialist on January 12, 2017, 12:01:01 pm
Miche track nuts with free spinning serrated washers! Changed from those that came with wheel/hub, hub King Kong! Getting really frustrated now, just tightened and reset wheel, went for ride of approx. 30ml and chain slack again!
Title: Re: Chain Tension
Post by: mrcharly-YHT on January 12, 2017, 12:55:36 pm
Only two things come to mind:
1) chromed dropouts
2) wheel kinked a bit when you tighten it up.

This is how I used to do it when riding fixed.

Pull wheel back, tighten up both sides with fingers. Using left hand down near the BB, push tyre/wheel back and slightly away from the chain a bit. Tighten up non-drive side.
Chain is almost certainly a tad slack.
with left hand push against side of wheel, shoving it over towards chain. This will tighten the chain and you should have wheel centred. Tighten drive side nut. Check chain tightness, rotating cranks. If chain is ok, do up both nuts bastard tight.
Title: Re: Chain Tension
Post by: Pickled Onion on January 12, 2017, 01:02:17 pm
, do up both nuts bastard tight.

This is key, but make sure you take the same length spanner with you in case you need to undo them!
Title: Re: Chain Tension
Post by: zigzag on January 12, 2017, 02:59:19 pm
in my experience 3/32" drivetrain needs to be adjusted every 2-300km (depending on weather conditions), 1/8" drivetrain at twice that distance, to compensate for the chain wear. if you need to do it more often it's likely that the axle is slipping - e.g. there might be some play in the chain tug device. if you are using half-link chain I'd swap it to a standard one.
fwiw, i use a closed cam qr skewer on my rear wheel and it doesn't need any additional retention on alloy dropouts - no slippage. i had to use a chain tug on steel dropouts as the skewer did not dig into them to prevent slipping.
Title: Re: Chain Tension
Post by: The Solo Socialist on January 12, 2017, 08:13:43 pm
Thanks Mr Charlie will try that way, what I've been doing is similar, but using chain tug to pull wheel central and tension the chain. I'm thinking of adding another chain tug to further stop any wheel/axle movement. I use a Park Tool which has a C Spanner at the opposite, the end to hex hole, tightening as hard as I can by hand, turning bike over and adding more tightening with my foot. So I would call it Bastard Tight. Frame is Steel, chain, chain ring and sprocket are 1/8", a little concerned I may strip axle threads or nuts at some point!
Title: Re: Chain Tension
Post by: The Solo Socialist on January 12, 2017, 08:16:01 pm
Thanks ZigZag,chain is standard 1/8, no half links!
Title: Re: Chain Tension
Post by: rogerzilla on January 12, 2017, 08:36:42 pm
Tugs (which I've never used; they're considered a bit infra dig in snooty fixer circles) usually prevent slippage totally.  Chain wear can be very rapid in wet conditions, and it only takes a small amount of wear to cause visible droop. so this is a bit of a puzzle.
Title: Re: Chain Tension
Post by: Ivan on January 12, 2017, 09:03:22 pm
What make/model chain is it? I find the cheap KMC ones stretch pretty quickly.

I agree that with tugs you shouldn't get much movement of the axle - the advantage of these is you no longer have to tighten the bolts so much and can get away with just a 4" adjustable spanner on the road, which I find does for the tugs and mudguards as well.
Title: Re: Chain Tension
Post by: Crumbling Nick on January 12, 2017, 09:50:46 pm
Firstly, you're correct that all is not well. I'm somewhat embarrassed to quote myself, but  this  (https://yacf.co.uk/forum/index.php?topic=75394.msg1588847#msg1588847) is the sort of distance you should expect before a new chain needs retensioning. That's 3/32" chain, so 1/8" should be significantly better.
Your question is very definitely not a stupid one. It is a simple question, and doubtless the answer will turn out to be simple. Nevertheless it's very far from simple finding what that answer is.
 
Various random thoughts: -
Chainring bolts - if they're too long, tightening with an allen key on the outside & the special nut tool on the inside might not have clamped the chainring against the spider. If you can't turn the bolts with an allen key & no nut tool without a lot of force, that looks like an unlikely cause. Is the chainring new?
Axle slippage looks unlikely with a drive-side chain tug & your tightening technique. A 1970s Holdsworth is most likely to have Campag dropouts. If they're not chrome plated, slippage is very unlikely, unless the track nuts are bottoming on something in the axle spacers, or maybe something on the inside of the dropouts. That ought to be visible with careful scrutiny. Symptom... have you checked whether the tyre/rim has moved laterally between the chainstays? RHS slippage can slacken the chain by the amount you describe with only around 5 mm of lateral movement at the rim.
Slippage of LHS of axle looks unlikely. On my 1980 touring frame, the tyre would be rubbing against the RH chainstay with the amount of slack you describe if it were a LH axle issue. Symptom to check is the same as for RH axle slippage.
I've had one chain that measured short of 1/2" pitch when laid out on the workbench. That stretched to a stable length during the usual installation & tensioning routine. That also seems a very unlikely cause.
Bearings... Is bottom bracket tightened securely? Tightness of RH crank on the BB spindle looks unlikely if it's a square taper chainset. Is it? Rear hub bearings look unlikely.. Any lateral play at the wheel rim?
Title: Re: Chain Tension
Post by: The Solo Socialist on January 12, 2017, 10:58:35 pm
Crumbling Nick,
Thanks for your reply, chainbolts fully tight no movement in chainring (chainring centred as much as possible as Sheldon Brown). No obvious obstructions around fork end nuts/hub, nuts seem to fully engage. Chain new, as are rear cog and chainring. Not checked wheel centre, though not noticed any brake rub, will do it all again tomorrow and check. Hopefully it won't change and it's
sorted. If not back to head scratching!!
Title: Re: Chain Tension
Post by: jsabine on January 12, 2017, 11:33:50 pm
You've reported a loss in chain tension: do you know for certain whether it's movement in the axle/tracknuts, or wear/stretch/elongation of the chain? With a chaintug, axle movement seems unlikely unless you've found a way of using it incorrectly: I'd be inclined to mark or measure axle position so you can eliminate this as a cause.

Title: Re: Chain Tension
Post by: hubner on January 12, 2017, 11:44:35 pm
Quote
forward facing drop outs, chain tug Surly

Aren't those chain tugs designed for rear facing dropouts (track ends)?
Title: Re: Chain Tension
Post by: jsabine on January 13, 2017, 12:00:04 am
Quote
forward facing drop outs, chain tug Surly

Aren't those chain tugs designed for rear facing dropouts (track ends)?

Assuming Tuggnuts, yes - but it's still possible to use them on FF dropouts, and the HurdyGurdy is designed for FF anyway - see 1st and second pics here (http://bicycles.stackexchange.com/questions/9146/are-there-tugnuts-made-to-fit-forward-facing-horizontal-dropouts).
Title: Re: Chain Tension
Post by: Crumbling Nick on January 13, 2017, 12:01:06 am
Brake clearance is minimally altered by axle movements (even asymmetric ones) with traditional horizontal dropouts. The critical measurement is at the chainstays. It's a PITA that brake clearance asseses very small errors (think about lateral accuracy of wheel-building/trueing), but lateral movement of the rim/tyre at the chainstays is less obvious if your frame has space for bigger tyres than the traditional  27"x 1 1/4" (630x32mm in more modern units). Nervertheless, lateral movement at the chainstays is "finger on each side to feel the gap" measurement & definitely not vernier calipers. Since you're in the process of eliminating causes, I'd suggest measuring the distance between the rim & the chainstay on each side with a steel ruler. Repeat after chain has slackened. Result is unlikely to be more precise than +/- a couple of mm, but you're looking for something bigger than that IMHO.
Title: Re: Chain Tension
Post by: hubner on January 13, 2017, 12:10:10 am
Maybe the dropouts aren't parallel.
Title: Re: Chain Tension
Post by: The Solo Socialist on January 13, 2017, 11:44:29 am
Thank You All For Your Help/Advice.
Today I've gone through all of your advice, I've checked everything you advised.
However on inspection it appears chain (KMC) is worn, measured over 12" its plus 1/8", which according to Sheldon Brown is excessive. Therefore as drive train has only been ridden some 300 ml
from new.  Chain is going back to Wiggle. What is they say about never assuming!

Which of course means Advice Request Again for Replacement Chain!!

Wheel nuts are open ended.
Drop outs are painted Steel, not chromed. Slightly chewed now especially left side.

With new chain may remove tug, as it seems to be frowned upon.
Title: Re: Chain Tension
Post by: rogerzilla on March 10, 2017, 07:55:15 pm
When fitting the wheel, tighten the LH, non-drive, nut (or bolt) first.  For some reason this helps avoid losing chain tension when you tighten the other side.  I can't remember where I read this, but it does work.
Title: Re: Chain Tension
Post by: The Solo Socialist on January 29, 2018, 01:59:48 pm
The plot thickens and deepens. New bike Dolan FXE, new chainset, bottom bracket, wheels, cog and chain. Addition of two chain tugs. So now the chain cannot slacken!!!
Except on its first Audax Windrush Winter Warmer 100 km plus 60 kms ride there and back, chain is now slack, wheels have not moved I referenced them. So what the question is Happening. Wheel nuts tight, chain tugs tight!!! Perplexed, confused and dismayed....
Could new chainring be wearing?????
Title: Re: Chain Tension
Post by: Phixie on January 29, 2018, 05:59:48 pm
It's more likely the chain is wearing, which gives the impression of it stretching.

Regards,

RP
Title: Re: Chain Tension
Post by: Ian H on January 29, 2018, 06:40:06 pm
Simple, quick check for chain wear: pull the chain away from the chainring at the 3 o'clock position (approx).  If there's significant slack, the chain is worn. 
Title: Re: Chain Tension
Post by: The Solo Socialist on January 29, 2018, 07:47:53 pm
Hi Ian,Phixie,
Chain is brand new out of the packet Saturday and fitted, first ride Sunday.... Hence my frustration, confusion???
Title: Re: Chain Tension
Post by: LittleWheelsandBig on January 29, 2018, 08:02:46 pm
A brand new chain is lubricated with grease. The grease tends to get pushed aside on the first ride, so the chain 'stretches' on the first ride and then the length is much more stable after that.
Title: Re: Chain Tension
Post by: Ian H on January 29, 2018, 08:08:07 pm
If you over-tighten a chain it will stretch quicker.   
Title: Re: Chain Tension
Post by: The Solo Socialist on January 29, 2018, 10:22:32 pm
Thanks for that LittleWheelsandBig, hopefully it will settle now then.
Ian I set the chain so that it doesn't bind at all, so maybe a bit slack to start.
Title: Re: Chain Tension
Post by: Manotea on January 29, 2018, 10:39:24 pm
But not too slack...  impressive, eh?

(https://www.dropbox.com/s/0glayelu11jw5bx/IMAG0320_1.jpg?raw=1)

Yes, that bike sure needs a clean!
Title: Re: Chain Tension
Post by: zigzag on January 29, 2018, 11:21:56 pm
But not too slack...  impressive, eh?

it is indeed!

in my (similar) case the weakest link was rear axle which got bent beyond repair; i had to get a new wheelset. slack chains can make a lot of damage to fixed/ss bikes!
Title: Re: Chain Tension
Post by: JonB on January 31, 2018, 02:12:02 pm
My chain (KMC 1/8") can go slack within a 100km especially if it's a hilly ride, I've re-tensioned during a ride on a number of occasions. I do think there's something in Ian's point above about the more you tighten it then it will 'stretch' quicker and so I've started to leave a bit more slack in it but nothing that's noticeable through the pedals. I used to think there might be some movement at the drop outs but then ruled this out as it would likely throw the wheel off centre. It's also worth noting just how little the wheel has to be moved to get the chain tight, the other side of that - it doesn't take a lot of wear to create slack.

How's the Dolan? Any pics?
Title: Re: Chain Tension
Post by: Sergeant Pluck on January 31, 2018, 03:59:17 pm
I've always had terrible trouble maintaining tension on my Bob Jackson. This has been the case with good quality normal axle nuts and a Phil Wood bolted hub. With both I have had to have them tighter than I am comfortable with, and once I have broken a bolt on the Phil. And that is even with ensuring that the surfaces are clean and free of grease. That was a high spec bolt chosen after getting advice on here.
Title: Re: Chain Tension
Post by: The Solo Socialist on January 31, 2018, 04:47:04 pm
JonB
Dolan all good so far, impressed with power transfer (not that I produce any power) but what I'm able seems to drive me forward. First Aluminium Fixed Frame I've ever owned. My other thing is a 1970 531 Holdsworth, so a little compliant.
I've read all the post's and maybe being a tad anal re chain tension. But having read and seen some of the comments re chain coming off is scary.
Title: Re: Chain Tension
Post by: rogerzilla on February 08, 2018, 08:19:31 pm
A small chainring and sprocket combination exacerbates the problem because chain tension is higher and it's all more fussy about slack spots than bigger cogs.  I had chains going slack in dry conditions within 100 miles on 39 x 14 (old MTB frame, so 26" wheels) but I rarely need to touch the 52 x 20 on my roadified track bike.  If you can cope with a few extra ounces, big-big is the way to go; it's much smoother and more pleasant to ride, unless you really like the more immediate feel of a small-small transmission.
Title: Re: Chain Tension
Post by: Jakob on February 09, 2018, 07:18:53 am
I think the drivetrain is the most important part on a fixed gear and it's simply not worth skimping on the pennies.
EAI sprockets, Sugino75 chainrings and HKK or DID chains. It'll be round and strong.
Title: Re: Chain Tension
Post by: rob on February 09, 2018, 01:00:12 pm

Dolan all good so far, impressed with power transfer (not that I produce any power) but what I'm able seems to drive me forward. First Aluminium Fixed Frame I've ever owned. My other thing is a 1970 531 Holdsworth, so a little compliant.


I have found mine very perky for what is a pretty cheap frame.   I was worried it would be a little harsh over the longer distances but it was comfortable on the 600 I did in September.   Mine is getting on for 2 years old and a bit beaten up from commuting and Winter miles so I'm going to get another one in the Spring for audax and weekend use.   It will more than likely be my choice for next year's PBP.

On the chain tension I use a surly tugnut on the drive side and retension the chain once a week as part of my usual weekend once over.   I will put a new chain on every few months and I use Izumi tracks which you can get for about 15 quid.   I'm not particularly great at keeping the bike clean so some items wear out quicker than they would if I had a little more time.
Title: Re: Chain Tension
Post by: Ivan on February 12, 2018, 02:28:54 pm
It will more than likely be my choice for next year's PBP.

Worked fine for me on the last one:
(https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/12031639_10153350128058138_2398334457091004649_o.jpg?oh=c6c6aee00578b4781863c41a07b37fda&oe=5ADB92D6)
Title: Re: Chain Tension
Post by: zigzag on February 12, 2018, 07:26:10 pm
If you can cope with a few extra ounces, big-big is the way to go; it's much smoother and more pleasant to ride, unless you really like the more immediate feel of a small-small transmission.

i agree and was planning to replace my current drivetrain (once it wears out) with a combination that removes the faff of shortening new chain, basically plug&play.
Title: Re: Chain Tension
Post by: Jonah on February 12, 2018, 08:52:27 pm
I think the drivetrain is the most important part on a fixed gear and it's simply not worth skimping on the pennies.
EAI sprockets, Sugino75 chainrings and HKK or DID chains. It'll be round and strong.

EAI cogs strip the threads on Phil cogs