new chainset

[Blodwyn Pig]

Olive has a Campag chainset with 48 39 28, running a 12-28 rear. Now I'm thinking of lowering a tad, with a stronglight chainset, should I go 46 36 26 , or 46 34 24.  Not done any loaded touring yet! but do ruff stuff, and Audax type stuff. Dont want a BIG range ie 11-34 at the back,as I like them a bit closer, hence 12-28?  thoughts anyone.

[Brucey]

it is all a matter of personal preference, but mixed in with practicalities like whether the FD you use is ideally matched to a 10T chainring interval or something different to that.  You don't say how many sprockets you are running at the rear; this may well influence the advice that is given.

FWIW when you are lugging a load, small changes in gradient often require larger than normal changes in gear ratio, hence widely spaced ratios at the bottom end  are more tolerable at least, if not preferable.

My personal preference when touring is to use a cassette that starts with a 13T or 14T sprocket, else a good portion of the cassette is wasted on small sprockets that are not that useful, not that efficient, and not that hard-wearing.

cheers

[Blodwyn Pig]

So Brucey,what cassettes are you using that start at 13/14 . Home brew? What range? 

[Oxford_Guy]

I'm going the other way with my 9-speed Hewitt Cheviot tourer, but meeting you in the middle - replacing the 42/32/22 chainrings on my SLX crankset with TA Specialties Chinook 46/34/24 rings, I run an 11-32 Shimano XT cassette on the back - could run 11-34, but prefer the closer spacing. Gives me around a 20" to 112" gear range, I think, which is enough for me and my use cases.

[Duckfoot1606]

This is a question I’ve been wrestling with for a while. I’m in the process of changing my Audax bike cranks to 48 38 28 to help with knackered legs at the end of a long ride, currently running 48/34. Rear is already 13 - 29 (10 speed Veloce triple shifters). I had the new triple cranks lying around, but I think at the next change lower still (46 36 26) is on the agenda. I spend so little time on high gearing in the course of a ride more lower end options seem a better bet

Sure you are aware, Spa Cycles are a good source for these more specialised options 👍.

A

[Brucey]

So Brucey,what cassettes are you using that start at 13/14 . Home brew? What range? 

mostly home brew ones.  Range varies with the bike and its intended use.

BTW I have a coupe of bikes that run a shortened cassette on a 7s freehub body; this makes for a strong wheel (with less dish) and makes a custom cassette easy; just delete the top sprocket.  You can run 8 from 9 or 9 from 10, that kind of thing.

cheers

[Samuel D]

Chainrings have to be chosen in combination with rear sprockets. And with today’s cassettes that usually start at very small sprockets, that leads to problems. Witness the new Shimano 105 range (R7000) with all cassettes starting at a useless 11T; useless, that is, if you match it with a 105 chainset, the smallest large chainring for which is 50T.

This problem was explored in detail on another forum.

Since I value efficiency and long life, and larger sprockets are more efficient and last longer, I like to keep the chainrings as large as practicable. That means the cassette should start with a sprocket no smaller than 13T. However, since about the 8- or 9-speed era, Shimano and Campagnolo have progressively wasted more of the cassette on 11T and 12T sprockets, and cassettes starting at 14T have disappeared (except for close-range junior racing models).

So in many ways, with 10-speed, for example, you pay the practical and economic costs of all those sprockets without getting utility in return.

Gearing can turn into a fetish – look what happened to Frank Berto – but the gearing of today’s bicycles suits hardly anyone. Gearing is the main reason I wouldn’t buy a built-up bicycle.

But before I ramble too much, Jan Heine has an excellent guide to choosing chainring sizes here and here.

[Oxford_Guy]

I do actually use the 11T cog on my tourer currently, with both the middle and outer rings, in fact one of my reasons to up the gearing to 46/34/24 was to need to use it less, and to sit around the harder-wearing middle cogs more, but to still have the 11T cog as something usable down hills on the 46T ring. Having said that, would probably still prefer a 12-32 cassette, if there was a Shimano option for that

[Cudzoziemiec]

It's kind of ironic that the only cassettes starting at 12 are the close-ratio racing ones that finish at around 23. Though OTOH I suppose it could be made to make sense also with a triple.

[zigzag]

both of the options would work fine, depending how loaded your touring bike is. some carry 10kg with them, some 40kg of stuff - gearing should be appropriate.

[Brucey]

I do actually use the 11T cog on my tourer currently....

but....

Q.  is it actually doing you any good?

..... to still have the 11T cog as something usable down hills on the 46T ring....

A. No, not really.

Let me explain; suppose your 11T sprocket gives you a 110" gear and you would otherwise 'only' have a 100" gear. In simple terms you can ride up to  10% faster on those rare occasions when the hill is steep enough (but not so steep you would be freewheeling faster than that anyway) ; say 33mph instead of 30mph.  It may be great fun to do that but even if you manage a whole mile like that you have only 'saved yourself' about ten seconds; a disaster in racing terms if you can't keep up, but when touring it is fairly inconsequential, and anyway having saved your effort instead you might well be more than 10s faster up the next hill..... 

Note also that in many cases you could go as fast by simply tucking in and freewheeling instead.   In addition note that the 10% 'benefit' of using that gear is the maximum possible; the average benefit is more like 5%.

So on a touring bike I would rather lose the smallest sprocket on a modern cassette and either have a sprocket that is more useful than that elsewhere in the cassette or (more often)  have fewer sprockets and a stronger (and/or lighter), less dished wheel, better chainlines, etc.

cheers

[LittleWheelsandBig]

I like being able to replace consumables like cassettes easily and quickly. Running stock cassettes allows that.

[Brucey]

I like being able to replace consumables like cassettes easily and quickly. Running stock cassettes allows that.

so does a shortened cassette. 

BTW if you change your chain promptly, there is no need for a new cassette, or no need for an entire new cassette.  In the latter case a single cassette may supply all the fast-wearing sprockets in a custom cassette.

cheers

[Blodwyn Pig]

slightly ot, but on the stronglight impact chainset with 4 visible spider arms, the  chainring has an insert for the hidden spider, does this just push/tap out?

[Cudzoziemiec]

So you buy a 10-sp cassette, take the smallest sprocket off and put it on a 9-speed wheel. Then does the lockring just screw on to the next sprocket? I've never noticed cos I've never had reason to look, whether there's a thread on that too. And what will you do with the "spare" sprocket?

[Brucey]

So you buy a 10-sp cassette, take the smallest sprocket off and put it on a 9-speed wheel. Then does the lockring just screw on to the next sprocket? I've never noticed cos I've never had reason to look, whether there's a thread on that too. And what will you do with the "spare" sprocket?

Since a 10s cassette fits onto the same freehub body as a 9s cassette you can't easily tighten the remaining sprockets.  Using a shortened cassette makes most sense if you have a shorter (7s) freehub body too; this allows you to have a wheel with less dish etc.

You can create custom 9s cassettes by removing the smallest sprocket and adding a new (larger) #1 sprocket, thus (say) an 11-28 can be converted to a 13-32 simply by adding a 32T sprocket (and its spacer) and removing the 11T one. However in 10s this doesn't work so easily because the #1 sprocket is dished.

If you convert a 9s cassette as described then a new 11-28 cassette supplies all the sprockets that are likely to wear. 

The unused 11T sprockets can go in the bin, where they belong.

cheers

[Oxford_Guy]

Brucey - I agree that the 11T cog may not be that relevant when touring, but bear in mind I also use that bike for other things - commuting, long reasonably fast unladed leisure rides and also the odd sportive. I only own two bikes currently - my Hewitt Cheviot SE tourer and a Brompton M6R-X, so they both need to perform a multitude of roles.

When touring my load varies from light to medium, I never use front panniers, for example.

[LittleWheelsandBig]

Given that this afternoon I am replacing the third Shimano freehub body needed in this household in five years, running obsolete 7sp freehub bodies isn't desirable.

During the height of Audax season, we would need to replace chains every couple of weeks to stay under 0.75% chain wear. It is easier to just replace both chain and cassette a few times a year.

[Brucey]

fair point about 7s freehub bodies but you can still buy one that will fit most shimano hubs (with the original style of interface).  Also I have never had to replace a freehub body on my own bikes; they are usually well enough  maintained and adjusted when necessary.  A drawback to the 7s scheme is that AFAICT there is no such thing as a 7s freehub body (with the conventional interface) that also has a rear seal.

I have contemplated shortening an 8/9/10s freehub body, but I think I will run out of screw threads for the HG-style lockring. Thinking out loud, one possibility is to shorten an 8s freehub body slightly (at which point it will not accept anything smaller than a 13T sprocket), and to fit the lockring with a spacer onto the top sprocket. With a 9s sprocket set the lockring could protrude ~3mm beyond the top sprocket before it is going to hit the dropout, so a ~1.5mm spacer could be used. I think it might work with a freehub body that is shortened by ~1 - 1.5mm, which should leave enough lockring threads.

BTW if you have a load of freehub bodies that you would like to be overhauled, let me know.

[also, it might make sense to rotate your chains out at weekly intervals at the height of the audax season, then assess them for further use on a bike that has a special cassette or to use them up on a bike that doesn't.]

cheers

[Torslanda]

slightly ot, but on the stronglight impact chainset with 4 visible spider arms, the  chainring has an insert for the hidden spider, does this just push/tap out?

Hi Blodders. I've just examined a Sugino XD2R crank (which I believe is functionally the same) and the hidden fixing uses the standard chainring nut & bolt but with the nut outwards and the bolt fitted from the inside.

I also have an SR Suntour triple crank - less rings - which has the hidden fixing threaded into the back of the crank arm. From memory it uses a longer than standard bolt, like the ones Shimano used to use on inner chainrings, and a plain spacer between the inner & outer.

HTH

[mattc]

Brucey - I agree that the 11T cog may not be that relevant when touring, but bear in mind I also use that bike for other things - commuting, long reasonably fast unladed leisure rides and also the odd sportive. I only own two bikes currently - my Hewitt Cheviot SE tourer and a Brompton M6R-X, so they both need to perform a multitude of roles.

I do quite similar rides to that (plus 10mile/25mile TTs) on 46x13. (highest pedalled speeds are probably flat tail-wind sections whilst wheel-sucking the club-run!)

You must have a shit-load more power than me to need a 19% bigger gear. Or like a cadence 20% lower.  I'm not very powerful, so I'm not ruling this out - I'm just stating the numbers!

Your choice

[Samuel D]

Like mattc, I did plenty of fast group rides with a top gear of 46Tx13T (about 95"). I was never dropped for want of a higher gear.

However, on those same rides were people who claimed to find a 50Tx11T (121"!) useful. These are usually the guys who whack it into top gear at the top of a big hill, regardless of their speed at that moment (slow) or the top gear they happen to have fitted. That should tell you how much thought they’ve put into this.

Even the pros sometimes do this in the Tour de France. You see them labouring out of hairpins at a glacial cadence just because their bicycle is fitted with an 11T sprocket. Pierre Rolland is terrible for this but I’ve seen many do it.

Even if a huge top gear is nice to have once in a blue moon, sacrificing the 11T and 12T gives you more benefit the rest of the time. The widespread use of the 11T tells me Shimano hasn’t figured out a purpose for 11 sprockets…

Your position on all of this has to be clear before you choose your chainring sizes.

[zigzag]

it's veering off-topic but while i dislike 11t sprocket for it's inefficiency, i need it for the chainrings of 50t or less otherwise i spin out on the downhills. 53x12 feels better, but 53t chainring is not really useful on a touring bike..
i've built a gravel bike with a 45x11 top gear and wide tyres raise the gear inch number a bit, but i accept that this bike is too slow to keep up on faster rides (with racing tyres) but that's fine, i've got other more suitable bikes for fast riding.
just came back from a training ride on my ss bike (79"), two thirds of the ride spent spinning like a loon between 40-50kph. it's good in terms of training, but not exactly enjoyable.

[Paul H]

cassettes starting at 14T have disappeared (except for close-range junior racing models).

For faster day rides (My version of faster anyway) I like the campag junior 9 speed 14 - 28 cassette,  with a 50/40/26 chainset.  I've no use for a gear above 95" and  the 26/28 it's as low as I can go without it becoming more practical for me to walk.  Quick calculation shows that I could get most of the range I like with a compact double, but it'd mean a lot more front shifts between the most used gears, so I'll stick with the triple.

[Oxford_Guy]

Brucey - I agree that the 11T cog may not be that relevant when touring, but bear in mind I also use that bike for other things - commuting, long reasonably fast unladed leisure rides and also the odd sportive. I only own two bikes currently - my Hewitt Cheviot SE tourer and a Brompton M6R-X, so they both need to perform a multitude of roles.

I do quite similar rides to that (plus 10mile/25mile TTs) on 46x13. (highest pedalled speeds are probably flat tail-wind sections whilst wheel-sucking the club-run!)

You must have a shit-load more power than me to need a 19% bigger gear. Or like a cadence 20% lower.  I'm not very powerful, so I'm not ruling this out - I'm just stating the numbers!

Your choice

I doubt I have more power, and ride pretty high cadence, so do you think I might be over-cooking it with 46T and 11T then? Having said that I frequently spin out downhill with 42T and 11T and also remember spinning out downhill, though not as often, when I had a 44T crankset - so I thought that 46T might be for the best.

So if 46T / 11T is too high, then the alternatives are either for me to send back the 46T ring and get a 44T, or else to use a custom 13-32 cassette - but I have neither the tools nor skill to create one. I guess there is also the 12-36 HG400 cassette, which has the same cogs as the 11-32, just swapping the 11T cog for a very low 36T - but even when touring not sure I'm going to need as low as 24T / 36T