Chainset change

[Ajax Bay]

What risk - from your post it's not clear (to me). The OP wants a double, and brooks no persuasion.
OP says: "bike is a hardtail (no idea which model) falcon, possibly 15yrs or more old, 6061 alloy frame with flat bars and already has 700c x 32c road tyres on"
So this is an 'old' MTB with 7sp (was freewheel, now cassette) and likely 130mm OLD, so the chainstays will not be radical and would not get in the way of a 34t ring, if necessary by using a slightly longer BB spindle than recommended. The chain line would be shifted out, but not cause an issue.
I agree the FD might struggle (curvature of the cage) from 42t > 50t but the FD is a triple so if it can manage a 42-22 20t difference then it'll manage a 16t - my phrase above was: "will achieve shifting satisfactorily"

 

[davidphilips]

I have 52-11 on my triple, can someone work out what speed someone who is a lot younger and fitter than I am attain because I feel sure I am never gonna find out 🙂

At a steady cadence of 80 with 25c tyres on 700 rims you would be going at almost 30 mph, or if you could spin at 134 then 50mph. Not very many could spin at 134 on a flat road with that gearing?

Speed Gear	15.0	20.0	25.0	30.0	35.0	40.0	Speed Gear
52x11	40	54	67	81	94	107	52x11

 

[notmyrealnamebutclose]

Why do you want to dump the triple?

Because I don't need it, there are no vertical lift shafts near me for which I can only imagine the gg would
be at all useful. s/ Also a twin has a better all round chainline, big ring brought in = less stress and wear on
the chain

there is a good chance it will be impossible to fit a 50t chainring

No plans to go to a 50t, 48 max or maybe a 46t, dunno yet. More chance I can likely use existing chain albeit
with the help from a quick link or maybe even 2 ql's if it has no undesirable affects ?
.

 

[Ajax Bay]

. . . there are no vertical lift shafts near me . . . Also a twin has a better all round chainline, big ring brought in = less stress and wear on
the chain

No plans to go to a 50t, 48 max or maybe a 46t, dunno yet. More chance I can likely use existing chain albeit
with the help from a quick link or maybe even 2 ql's if it has no undesirable affects ?
.

Chain line: No significant difference and zero difference on 'wear and tear'.
The reason I suggested a 50-34 compact was because of your 'need for speed' and unwillingness to change the cassette to a 11-xx (from 12-xx). Would also be cheaper than getting a 48-32 (but not as cheap as a 48-38-28 ).
Chain length: I will reiterate this one last time. If you increase the large chain ring from current 42t to (say) 48t, that's 6 more teeth and 38mm more round one half of the ring (where the chain engages). Unless your chain is too long now, you will need at least one (inch) link more, and probably 2. This can be achieved by either a new chain or an additional one and a half links plus a quick link. Your LBS will surely let you have a bit of 6-7-8sp chain.
"there are no vertical lift shafts near me" - you need to get out and about more. Find a few chevrons and discover your "gg".

 

[Sharky]

with the help from a quick link or maybe even 2 ql's if it has no undesirable affects ?

You can't use a standard quicklink to increase chain length. You would have to take out one of the outer links, to replace it with a quick link.

But you can get new 7 speeds chains from as little as £4.99 from Halfords, so not worth messing with make-do's.

 

[notmyrealnamebutclose]

You can't use a standard quicklink to increase chain length. You would have to take out one of the outer links, to replace it with a quick link.

But you can get new 7 speeds chains from as little as £4.99 from Halfords, so not worth messing with make-do's.

yes I put that in there as a bit of tongue in cheek to see who was paying attention
The new(ish) chain is a 115 link iirc, 6/7/8 sp. I'm guessing the manufacturers sell these chains to fit a fairly broad range of chainset sizes but obvs cannot cater for every size chainset combination.
One can only assume they come on the slightly long size in order for the consumer to custom fit them (take/cut links out) of them if needed. Is it reasonable to assume this chain of mine will comfortably fit a 7sp 12-28t x 46-30t? Answer is Idk for sure ofc but it doesn't really bother me at this stage as later on I can hopefully butter up and scrounge a few left over 6/7/8 sp links from a non local LBS, lol! I'll just tell them my mate Ajax sent me o0

 

[Jameshow]

yes I put that in there as a bit of tongue in cheek to see who was paying attention
The new(ish) chain is a 115 link iirc, 6/7/8 sp. I'm guessing the manufacturers sell these chains to fit a fairly broad range of chainset sizes but obvs cannot cator for every size chainset combination.
One can only assume they come on the slightly long size in order for the consumer to custom fit them (take/cut links out) of them if needed. Is it reasonable to assume this chain of mine will comfortably fit a 7sp 12-28t x 46-30t? Answer is Idk for sure ofc but it doesn't really bother me at this stage as later on I can hopefully butter up and scrounge a few left over 6/7/8 sp links from a non local LBS, lol! I'll just tell them my mate Ajax sent me o0

Yes it will fit.
You will probably have to take a few links out.

 

[Ajax Bay]

At present with chain in large large, what position does the cage point (eg 5 o'clock)? If 6 or more you may be ok with a 46t. Most likely your current chain will not fit.
Two choices: 1) Fit new chain set and see if long enough (chain on large large). If not 2) Buy new chain
Adding a couple of links with a quick link will save minimal money (678sp chain), as @Sharky said.
Once you have fitted new 48t (or whatever) ring, put new chain on (as supplied will be too long as @Jameshow said) and lead directly (not through RD) round large large and add one inch link. That is correct length. Cut and fit.

 

[notmyrealnamebutclose]

It's choosing the correct length of the new bb spindle that's got me a pondering atm.
Too short risks the inner chainring in too close proximity to chainstay, too long then the big ring will throw the chainline out at an undesirable angle when in the larger rear cogs, ie cross chaining which will stress the chain and
eat away at the teeth leading to the premature death of the components. This ofc can be avoided by being in the correct chainring at all times but in practise, well you know

 

[Ajax Bay]

A new chainset will come with a recommended BB spindle length.
A few mm right (ie by going with a 113 as opposed to a 110) will not make much difference though I suspect with age of bike the inner ring of 2 will still clear the chainstay. How far is the small ring from the chainstay now? If that ring (?22t) was a 34t its radius would be about 24mm more. Extend the current ring line to the chainstay by eye. Still clear, or not? If not how many mm right would keep it clear?
You are stressing over chainline waaay too much. Where are you getting this "stress the chain and eat away at the teeth leading to the premature death of the components"? lmao
You shouldn't be in the largest 2 sprockets anyway when chain on large chainring.
The issue (not chain wear) if you push the chainset too far right (eg 10mm) is that the FD cage won't reach far enough to shift onto the large ring.

 

[Sharky]

I think by now, you have so many suggestions and tips, that all is required now is for you to get started on the upgrade.

But before you start and if your real aim is to go faster, collect some real metrics on your current set up. Time/speed on known hills, routes etc, make the changes and report back.

 

[notmyrealnamebutclose]

The shiny parts have just arrived, looking forward to the challenge!

 

[notmyrealnamebutclose]

Quick question, can a new bb spindle be pushed out of line, like be moved whilst tightening
up the non DS collar. It seemed stiff to tighten and the lh spindle seems to stick out about 3-4mm
more than the DS. I haven't fully tightened non DS it was getting dark and i wanted to have a quick
ride on it, seems ok but idk for sure

 

[Big John]

Yes, it's possible. Take a look inside the bottom bracket shell and see if there's a bolt or rivet sticking up about half way along the shell. This'll be the rivet/bolt that secures the cable guide to the outside of the bottom bracket shell. If this bolt/rivet is throwing the BB out of line you'll need to remove it.

 

[notmyrealnamebutclose]

Yes there's a cable guide screw but it didn't feel like it was fouling the bb body

It's this one but a 113mm, I thought DS looked odd after i had tightened NDS like I had forced it
over but is normal looking at this.

How much of the NDS thread should be showing (if any) after being fully tightened it's a bit
different to th old bb, old bb NDS had a bearing cup/race that slid off thw spindle, this one is
fully sealed I don't want to over tighten it. SFLR