Urban75 Home About Offline BrixtonBuzz Contact

I need a 38 tooth middle chainring for my bike...

gentlegreen

gentlegreen

I hummus, therefore I am ...
Why are they so elusive or ridiculously expensive ?
I only need it for a year (hopefully)
I probably already have an chain and 8 speed cassette and just this worn middle ring - it's cramping my style and nasty.
I run 28-38-48 square taper...
 
Last edited:
weepiper said:
That's a 9 speed one. Edit because I thought I had an 8 speed one but was wrong. What exact chainset do you have gentlegreen?
Click to expand...

I'm running an 8 speed Shimano megarange
Thanks, but that's a 32T - and googling only finds more...

It seems I could get a somewhat nasty welded crankset for £30 ... I can probably still locate an alternative ST bottom bracket if I need to ... otherwise that's another £10...
It only has to last me a year and then so I can sell the bike in good conscience ...

 
Last edited:
Well I've found a new chain and a new cassette and a 68mm bottom bracket so I assume the longer one is already on the bike - so I will order an Altus FC-M311
 
weepiper said:
That seems like the easiest answer. That chainset needs a 122.5 BB axle.
Click to expand...
Thanks - I just searched Urban and it seems you had me buy one before when I bought a cheapie crankset - I suspect it's the one in my spares box because it has copper grease on it so I must have removed it to put my old axle and Alivio back on. :thumbs:
It would be good if I could get reasonably fit by the end of the year and back to doing regular 20 mile rides again.
 
I noticed the rear mech is a bit knackered ...
I would not want to find myself stuck 4 miles from home let alone 12 ... and I've never tried improvising single speed ...
Luckily the cheapo X3s appear to be available again so only £15 ....
It seems I bought the current one in August 2018 so it's done 3,000 miles.
I can remember hobbling home from 1 1/2 miles and having to walk to work until it arrived - this way I can keep the old one in my bag as a spare.
I'm trying to resist buying another tyre - I'll see how it goes.
I've been taking my cheapo stand pump on rides ...

1684598855084.png
 
Last edited:
I went out for my first proper (and hilly ride and learned that not only is the bike up to it, but so am I.... :)
So the new rear mech will be worth it.
I deffo have a too short BB on - making the chainline is a bit iffy in some combos so I'll need to have another look at some point.
I'm getting away with it because the chain-stays are recessed at that point - ho hum.

Maybe once the current wounds have healed - note to myself to wear heavy gloves next time...
 
Last edited:
Damn.
On this particular frame, the 122.5 BB axle is correct for the Deore, but still too short for this cheapo chainset ... my old BBs are 110mm
On the lowest gears, the chain is starting to brush the spokes ... it seems the longest available is 127.mm ... how to get the right one ?

1685180416646.png
 
Last edited:
Oh well.
I'm not sure now.
I'm not even sure what I was hearing in the lowest ratios - perhaps just the front mech ...
I fitted the new rear mech and I seem to have a decent range of gears ... just as well I don't try to do everything on the middle cog.
I'm massively out of practice with bike mechanics and also stressed-out...
 
Just gave it 10 miles including a decent hill and nothing broke or fell off...
a bit clackety in some ratios, but fine for the steady terrain of the railway path.
I suppose I ought to do it again without earphones just to be sure.
I was originally only going to a quick 2 miles down and then back, but in he event I was almost tempted to do 20 miles - maybe tomorrow.

So chances are the previous chainset was further out to the right than it should have been - by 12.5 mm - or 2.6 sprockets ...
 
Last edited:
gentlegreen said:
Damn.
On this particular frame, the 122.5 BB axle is correct for the Deore, but still too short for this cheapo chainset ... my old BBs are 110mm
On the lowest gears, the chain is starting to brush the spokes ... it seems the longest available is 127.mm ... how to get the right one ?

View attachment 376422
Click to expand...
That chainset should use a 122.5 on any frame. If you're hearing the chain brush the spokes in the biggest sprocket of the cassette it means the gear hanger or the rear mech is probably bent. Stand behind the bike and look at the angle the cage of the mech is sitting at relative to the cassette sprockets. It should be in line with them. If it's tilted in toward the wheel then that's your problem. You may be hearing the chain rubbing on the inside plate of the front mech too, in which case you either need to undo the low limit screw a little bit or reduce the cable tension a little bit, or both.
 
weepiper said:
That chainset should use a 122.5 on any frame. If you're hearing the chain brush the spokes in the biggest sprocket of the cassette it means the gear hanger or the rear mech is probably bent. Stand behind the bike and look at the angle the cage of the mech is sitting at relative to the cassette sprockets. It should be in line with them. If it's tilted in toward the wheel then that's your problem. You may be hearing the chain rubbing on the inside plate of the front mech too, in which case you either need to undo the low limit screw a little bit or reduce the cable tension a little bit, or both.
Click to expand...
Thanks:)

Fitting the new one probably fixed it :)
It was all quite sloppy - as is the Shimano front mech.

Just having had the remains of my 20 year old Specialized hybrid turned down by the bike project, the scrap man is having it this week so I started sorting out my hoard of old chains and mechs to go with it (those with metal side plates) and there were a lot of them.
I also bought several complete Deore chainsets over the years for some reason, so all those parts will go for scrap too...

Hopefully in proper retirement I will be a lot less heavy on my bikes... who knows, geography might dictate a single speed beach bike might be an option...
 
Look what I found during my house-emptying ... :p
Now I know how rare they are I'll have to make sure I sell it.
Chances are the 28 and 48 tooth sprockets may have been a bit worn anyway, but ...

newcog.jpg
 
Since this is my gym machine for the next 9 months at least, I finally decided I should stop avoiding the reluctance to spend more on this bike as well as following two months of house-clearing acquiring any more stuff than I will consume in a week ...

So I finally acknowledged that I needed to tackle the hydraulic disc brake pads - and yesterday morning verified that one of the front pads was down to the metal...

I ordered at 11am on Sunday, delivered 8 hours later - crazy times - I could have had them in for the commuting on Monday that I no longer do ..
Only minimal blood drawn - avoided all the obvious hazards of the process and got caught in the clamp on my repair stand - being my index finger I hope it doesn't take the edge off my ride later...

The back pads were still pretty good, but one of the front pistons is clearly not pulling its weight and the over-compensating one needed a good poke - so it needs a stripdown / bleeding / replacement etc, but I will leave that to whoever buys the bike from me - maybe I'll swap the pads over at some point ...far too late I read the suggestion that a nylon tyre lever was a good thing to use to prod the pistons but I was careful ...

I will probably have no choice when I buy new bikes in France, but I would definitely prefer cable disks and forks / frames that would let me carry an emergency pair of vee brakes...

--------------

I've been carrying my backup track pump on my ride to slightly mitigate the hell of trackside repair, but two more smashed bottles on my route saw me order a decent tyre for the back ...
£22 - I used to pay a tenner for tyres like these and sometimes got a free inner tube ...
I'll take a chance on the front one as there is so much less injury / damage / mess potential - but I'll still carry the pump...
Hopefully before too long I'll start going for 20-something mile rides again...

1688992957317.png
 
Last edited:
Just gave my brakes a test ride - much more pleasant.
Torn between using the front brake more to try to free the sluggish piston - or less to lessen wear and tear.
It isn't very critical due to where I mostly ride and avoiding braking wherever possible...
 
Last edited:
gentlegreen said:
I will probably have no choice when I buy new bikes in France, but I would definitely prefer cable disks and forks / frames that would let me carry an emergency pair of vee brakes...
Click to expand...

I'd LOVE to go back to cable brakes. Had a drama in lockdown and ended up using baby oil in my hydraulics much to the disgust of everyone I've ever spoken to about it... they're just such a hassle eh? No maintenance my arse. I'd take V brakes any day given the choice.
 
Clean the pistons, because you're going to fuck the seal if you keep riding with a sticky piston.

You can push the pistons (partially!) out of the caliper with a cable tie over the brake lever and clean the exposed surfaces with a cotton bud and brake cleaner spray decanted into the cap. Don't push the pistons right out of the caliper!
 
DownwardDog said:
Don't push the pistons right out of the caliper!
Click to expand...
That's what's stopping me - as I have no fluid or bleeding kit ...
I'm literally just using this to ride up and down a converted railway path and hope to sell the bike on next year...
To be honest all I have is that one piston was sticking out and one pad was worn ...
Worst case I have a mechanical disc unit I could fit ...
 
If you are windy about pushing the pistons out of the caliper then put something between them.

A disc is 1.8mm thick. 5 x business card or similar are 1.5mm thick so that will give good piston exposure without ejecting them from the caliper.
 
DownwardDog said:
If you are windy about pushing the pistons out of the caliper then put something between them.

A disc is 1.8mm thick. 5 x business card or similar are 1.5mm thick so that will give good piston exposure without ejecting them from the caliper.
Click to expand...
I'll have a look tomorrow when my new tyre arrives - I may just have misinterpreted what I saw - I may just have allowed the pads to wear down too far ...
 
I just found my micrometer ...
Front :-
2.2 less 1.6 = 0.6 (where there's actual pad)
2.5 = 0.9
back :-
3.3 = 1.7
3.1 = 1.5

Apparently 0.9mm of pad is the replacement point so I could have left the rear ones...
 
Last edited:
You must log in or register to reply here.

Similar threads

kalidarkone
How much should I sell my van for?
2
Replies
33
Views
1K
kalidarkone
kalidarkone
fucthest8
Hybrid e-bike for commuting
Replies
12
Views
491
newme
newme
sim667
e-bikes for people who have pain when walking?
Replies
10
Views
381
sim667
sim667
gentlegreen
Rear mech positioning screw issue on steel bike frame...
Replies
12
Views
465
gentlegreen
gentlegreen
B
Buying an electric cargo bike?
Replies
14
Views
625
likesfish
likesfish
Back
Top Bottom