Changing double to triple - BB choice/Crankset choice?

[531colin]

Oh dear, here I am confessing to another brain fart.



Thats the chainset have been riding. As before, its 30/46T, but the 46 is actually a "big" ring, not a "middle" ring, so the recess for the chainring bolt is the "wrong" side. There is clearance between the chainring bolt head and an 11 speed chain on the 30T chainring, but its close...



Other chainring sizes, other chains, and even different days of the week might result in conflict between chain and bolt head.

The blanking pieces (blanking off the big ring position) are cut from an old chainring, or a chainguard also works, as above......
.....still a product in development!

[Ray]

Thats the chainset have been riding. As before, its 30/46T, but the 46 is actually a "big" ring, not a "middle" ring, so the recess for the chainring bolt is the "wrong" side. There is clearance between the chainring bolt head and an 11 speed chain on the 30T chainring, but its close...
Other chainring sizes, other chains, and even different days of the week might result in conflict between chain and bolt head.
.....still a product in development!

Hi Colin
(warning - I'm in serious danger here of falling foul of grannies and egg-sucking. It's almost certain you'll be quite aware of what I'm about to say, so apologies - but the problem interests me - and maybe others?)

I'm a bit surprised to see that you're using an 11sp chain. I guess that is because an 11sp cassette gives you a better range of gears with a double chainset? If, however, your choice of a narrow chain is simply to get greater clearance for the chainring bolt, would it not be better to find a 46t 'middle' ring with recessed bolt holes? Like this - http://www.spacycles.co.uk/products.php ... 0s113p1722 - quite an expensive piece of bike jewellery, which it would be a pity to hide behind a chainguard!

Cheers

[531colin]

No worries, Ray...
The 11 sp. chain is due to the bike being built up with an achingly trendy 11sp. 105 set. Although the full-hydraulic disc brakes are quite astonishing, it limits you to 1 less chainring than I would really like, hence the search for an "ultra" compact double, for a reasonable price. ( NOT http://www.sjscycles.co.uk/chainsets-middleburn-spiders-dept990_pg1/ OR http://www.gravelbike.com/?p=1799 !)
The TA rings you link would do the job for sure, but when the Spa ones land they are likely to be a better price..http://www.spacycles.co.uk/products.php?plid=m2b0s210p0

[Samuel D]

hence the search for an "ultra" compact double, for a reasonable price.

Would these SunXCD cranks be any use? I’ve been using them with 46T and 34T chainrings and they can be configured to accept smaller inners than that. Whoever makes them may be persuaded by Spa Cycles to make them for substantially less than Velo Duo’s retail price of £65.

SunXCD website here.

[531colin]

Good "heads up"....thanks.

[GRAVELBIKE]

Sugino has replaced the OX601D and OX801D with the OX901D. Same 110/74 PCD, but the 901 is 11s compatible and has a nicer finish. Definitely not cheap, however.

In the past five years I've gone from a triple, to a double, and now ride a single-ring setup. With 11-42t cassettes available from SunRace, it's easy to get a 1:1 low gear.

[poppet]

So the only way to go lower than a 30 with an external bearing bb is one of these Sugino jobs? How low do people generally go for laden touring? I definitely struggled with my current low of 34

[Brucey]

there are some (now older, mostly 9s but could run 10s if necessary) shimano triple designs that use 74mm BCD inner rings and EBBs. Until very recently such chainsets were still available new and there may still be stock in some outlets. From memory ultegra, 105 and tiagra groupsets were like this at various times with 130/74mm EBB triples.

edit; some techdocs

FC-6603http://web.archive.org/web/20150620024225/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC//FC-6603-05.PDF

FC-5703http://web.archive.org/web/20150629132031/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC//FC-5703-3004.PDF

FC-5603http://web.archive.org/web/20150620161827/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC//FC-5603-2440B.PDF

FC-4503http://web.archive.org/web/20150629131919/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC//FC-4503.PDF

FC-3403http://web.archive.org/web/20150620151738/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/FC//FC-3403.PDF

Any of these will accept a standard 5x74 chainring down to 24T (but it will be a big jump to the 39T middle ring...). FC-5603 is still listed at SJS.

cheers

[531colin]

So the only way to go lower than a 30 with an external bearing bb is one of these Sugino jobs? How low do people generally go for laden touring? I definitely struggled with my current low of 34

I gear as low as I conveniently can, which is 24 front, 34 rear, with a triple, but I'm 68....10 years ago i couldn't see any reason to gear lower than 1:1, like "Gravelbike"
But this thread gets bewildering.....why do you want an external bearing BB for touring?
I thought you were interested in low gears reasonably cheaply, which to me means a 2-rings-from-3 conversion of a triple....square taper is not only a longer-lasting bearing, you can adjust the chainline to use your existing mech. and shifter. If you go for a triple of any sort, don't you need a new shifter and mech?

(.....and isn't it hilarious what some sections of the bike trade will sell unsuspecting customers as being "ideal for touring"....)

[poppet]

Agreed, it has gone off course and bewildering. I hadn't thought about any other ways to lower my gears than fitting the standard triple Shimano which was my original intent. It's been useful to get the alternatives. And agreed a square taper would be longer lasting/adaptable. I was trying to keep things simple, if only in my head!

PS I do want to change the shifters anyhow, those clothes lines are annoying me.

[531colin]

Downtube levers are the most direct cable run.

[poppet]

..or one of these?

http://www.lindarets.com/roadlink/

[Brucey]

..or one of these?

http://www.lindarets.com/roadlink/

interesting, but there are problems;

1) whilst you might be able to use a larger sprocket, the total capacity of the mech is not increased, so with most wide range gear systems (using a double or a triple especially) there is a danger that the chain will run slack in some gears.

2) the mech is likely to end up further away from the smaller sprockets on the cassette. If this happens the result is likely to be that the shift quality on the smaller sprockets will deteriorate; this is something that the manufacturers hint at with their 'individual results will vary' caveat.

cheers

[freeflow]

If its any help I am running a shimano M770 9 speed triple ( XT 44/32/22) with 10 speed ultegra 6603 shifter and a 10 speed chain. The front mech has to sit way higher than shimano recommend to stop it fouling the chainstay when on the smallest chain ring. Very occasionally I get a bad graunch when chaning at the front but this is usually when I forget and try to change two click at one rather than one click 3 or 4 pedal strokes 2nd click. I've done near on 8000 km with this setup now.

[GRAVELBIKE]

If its any help I am running a shimano M770 9 speed triple ( XT 44/32/22) with 10 speed ultegra 6603 shifter and a 10 speed chain. The front mech has to sit way higher than shimano recommend to stop it fouling the chainstay when on the smallest chain ring. Very occasionally I get a bad graunch when chaning at the front but this is usually when I forget and try to change two click at one rather than one click 3 or 4 pedal strokes 2nd click. I've done near on 8000 km with this setup now.

xt chainset gap.jpg

I've heard that Shimano's CX front mech works better on smaller-sized chainrings.

http://www.rivbike.com/product-p/d14.htm