the standard commuter bike came out of the shed this morning after a winter unused. i'd given it the once over on saturday - pumped the tyres, checked brakes, oiled the chain a touch etc. as i was putting it away i did notice a teeny line of oil on the crank but it was late, sun was going down, other things beckoned blah blah.
3 miles in to its 2019 debut, set off from the lights and - crack - the thing snapped clean off maybe an inch and a half from the axle end
mig wrote: - crack - the thing snapped clean off maybe an inch and a half from the axle end
what's a decent fixed crank set these days?
-what, you mean one where each crank is in (ahem) one piece...?
Lasco cranks are not too bad. If you can find a friendly Giant dealer they may have one that they have taken off a bike; they fitted them to some commuter bikes and they prevented fitment of some chainguards because of the forged spider.
Andel cranks are styled like classic cranks (and take 144BCD chainrings) but presumably they will suffer throat cracking just like they used to (is this what did for yours BTW?)
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope You'll Still Find Me At The Top Of A Hill Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
i might, possibly, have a sugino crankset from a track bike used once upon a time. will have to sift through the spares box(es.)
it was a stronglight escape crank.it is maybe 20 years old and has amittedly done some mega miles. up hill and down dale. i'd had an eggring made for it many years ago and that thing has lasted as if untouched by a chain. it really does look unmarked. unfortunately the same cannot be said for the crank. the crack itself has a marked diagonal line across the exposed face, half clean, half dirty. obviously been going for some time. waiting to pounce.
try keeping your balance whilst removing a pedal and a length of crank from your right shoe amidst buses, a line of cars and a bl**dy tram!
ive done this a few times. Clamp a 144bcd ring to your egg ring. Use this as a guide to show you were to drill the bolt holes and cut the excess material away to fit your crank. All you need is patience and some tools, Hacksaw, files and an electric drill should suffice. BTW ive got an escape chainset fitted to my folder, the cranks were shortened to 150mm by Highpath, i'll keep an eye on them.
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway X2, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840
I would advise getting a competent machinist to modify the chainring. The reason is that if you are running fixed and you are fussy about chain slack, the slightest amount of off-centred-ness will drive you crackers.
I may have a pair of stronglight 100 cranks somewhere if you want to carry on with 86mm BCD. If my memory serves me correctly they aren't great but they will keep you mobile until you sort yourself out.
Brucey wrote:I would advise getting a competent machinist to modify the chainring. The reason is that if you are running fixed and you are fussy about chain slack, the slightest amount of off-centred-ness will drive you crackers.
I may have a pair of stronglight 100 cranks somewhere if you want to carry on with 86mm BCD. If my memory serves me correctly they aren't great but they will keep you mobile until you sort yourself out.
cheers
aye i might well take you up on that.
does riding fixed place extra demands on cranks as they flex both ways? also it is likely that this crank started to crack at the 'back' as it's harder to keep clean and corrosion set in?
one of the places where cranks routinely crack is in the 'throat' between the spider arms and the RH crank, like this;
and eventually
The sharp knife-edge in the throat is extremely poor design; almost guaranteed to start cracking; most crank makers have produced designs with this bad feature and some still do. If you have cranks of this kind and you want them to last well it is a good idea to file a better shape in this part of the crank. Small cracks can (indeed must ) be filed out completely. IME anodised cranks are more likely to crack in winter use too; the reason is that once there is a small breach (crack) in the anodised layer any corrosive attack is extremely localised and this accelerates the crack growth rate.
As a rule of thumb any part of the fracture face that has gone black is the oldest part and has probably seen winter conditions.
I don't think that loads in the crank arms are enormously increased by running fixed but they are not exactly reduced, either.
Beware of used Sram Omnium cranks, I've seen too many cracked by the pedal hole, even though there is a substantial amount of material. Miche track cranks do not like to be abused, too. Never seen cracked ones that were used properly, all the ones that cracked by the pedal hole did show some very nasty marks of impact of some sort; then used far beyond what they were meant to do.
It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are...
i bought some sugino cranks of some sort second hand a few years ago for such an eventuality as i ride fixed quite a bit october-april. i believe that they're okay quality wise and don't look to have been hammered previously.
don't cranks break at the pedal end if they've been over tightened using huge spanners & pressure from feet etc?
the sugino chainset is on with a 'ring of unknown usage (although it looks okay.)
using a phil wood (i was given it) cog (that looks okay.)
new B1 chain.
this set up runs fairly okay on the flat with a little grumbling.
but like a bag of bolts going up a steep climb.
how many miles do i give this to 'bed in'? or should i just bite the proverbial and throw £40 at a new chain ring, chain and sprocket (awaits that kentucky dude to calm down the spendy nature of this post.)
The B1 chains are very noisy with even slight mismatch in wear. Not sure how long it takes to go away as I just bought a new sprocket and flipped the chainring.
Couldn't you do the same, same chain, reverse the chainring and fit a new sprocket?
there will be noise under load if there is even the slightest hooking of the chainring or the sprocket. B1 chains are (IME) very accurately made (I measured 5.000" for five links), and have rollers that don't have much slop in them. This makes them intolerant of slightly worn sprockets. I fitted a new B1 chain on an IGH sprocket that had the slightest wear marks and the chain was noisy for about 500miles. I think
The sprocket eventually settled down but before it did (amazingly) there were small burrs cast inwards by the chain as it engaged (noisily).
My cunning plan is to wear couple of B1 chains to about 0.25% and to keep those for use on slightly worn sprockets.
it's settling down now after 353 miles. probably be silent just as it wears out i'm trying to clean it up a bit more than usual as i assume 'wearing in' is going to create lots of particles of wear from the transmission.
might try an S1 next.
is that level of build accuracy on the B1 chain rare?
nb. cheers to the white van man who came hurtling past this morning at 40ish, wing mirror at my elbow but who had seemingly failed to see that HUGE queue of traffic some 100 yards ahead. good job that your brakes worked chief....and that fiesta ahead was the extra inch forward. lunatic.
