Smaller compact chainset?

aukray

My bike came with an Ultegra 6700 10-spd groupset with a 34-50 Hollowtech chainset. In order to get lower gears and less of a jump between rings I'd like to fit something like 30-42. As 34 is the smallest available on the current chainset, I'll need a new chainset, and would, if necessary, be quite happy with a less pricey, non-matching set. I'd hope not to have to change the STi levers.
Can anyone say what chainset might do the job? Is there anything available which would allow me to use the existing external bearing B/B? Again, if need be, I don't mind fitting a traditional B/B.

Thanks for any help.

P_Tucker

Have you considered getting a bigger cassette? You can get an Ultegra 16-27 which might do the job.

aukray

Yes, thanks, I have used a 16-27 which is a partial remedy, but still don't like the 16-tooth jump on the c/set. I would like also like smaller gears for long alpine climbs (and, to be frank, for the good of my aging legs!)

jimwin

Can anyone say what chainset might do the job? Is there anything available which would allow me to use the existing external bearing B/B? Again, if need be, I don't mind fitting a traditional B/B.

Stronglight make all sizes of chainsets but, I think, old style BBs. Be careful you don't exceed the capability of the front ring changer.

I also recall seeing an article recently about a new rear cassette with a 32 sprocket ring. That gives a 28.6 inch gear which will get you up almost everything. It was either from SRAM or Shimano but you'll have to research the details

- Jim

jimwin

Forgot to add...

Maybe you should consider a triple with 50/40/30 rings?

- Jim

Pokerface

Why not just get a triple chainset then? You get smaller ring on the front and wider choice of gears (and the jumps won't be too large).

aukray

A triple would give me plenty of gears, it's true - and probably more than I'd want at the top end. Big problem, however, is that I'd need new STi levers and front changer, which makes me wonder whether it's worth the expense.

Unless there's someone out there with a comparable triple set-up who'd like to trade it for a compact?

Pokerface

Do those Ultegra shifters work with a triple also? I know there is one set of shifters that do Maybe a different set though.

aukray

I'm pretty certain the double/triple levers are not interchangeable. They certainly work beautifully with the existing indexed set-up, and I'd be a bit nervous about changing it too radically.

dennisn

FWIW TA speciaties makes a 33 tooth inner ring for compacts. If you're looking for less of a difference between your 34-50 just put on a 36 tooth small ring. I tend to find a 34
tooth ring a bit small for anything but mountain climbing. I live on the flattest part of the planet and a 50-36 with a 12-21 on the back is just right. You can always shift back to a 50-34 and maybe a 12-27 when you're going to be mostly climbing.

John.T

http://www.spacycles.co.uk/products.php?plid=m2b0s109p43
44/29 do you.

dennisn

John.T wrote:

http://www.spacycles.co.uk/products.php?plid=m2b0s109p43
44/29 do you.

Wow, that's a new one on me. Could be made to be very workable for loaded touring, i would think.

CarlosDSanchez

There are quite a few mtb 10spd double cranksets around these days. You should be able to find one compatible with external bb and say a 42/30 big/little ring. Only saw the xtr shimano version which is £££s but there are much more reasonably priced sram versions.

Pokerface

John.T wrote:

http://www.spacycles.co.uk/products.php?plid=m2b0s109p43
44/29 do you.

That needs a special BB? Any problem fitting that to a road bike?

Berk Bonebonce

As per previous posts, Spa Cycles are the people to ask.

I run Stronglight Impact double with 34/42 rings. Check out their website.

Pokerface

Berk Bonebonce wrote:

As per previous posts, Spa Cycles are the people to ask.

I've purchased from them before. Probably a series of bad luck - but found their customer service to be shockingly bad.

maddog 2

check out the Middleburn duo (29/42 and 32/44)

TA also do various spiders for the Carmina crank - you could run a 4-bolt spider and 32/44 (This is what my wife runs on her roadie).

Also look at the latest tewo-ring MTB setup (Sram XX, Truvativ Xo, X7 and X9, Shimano XTR) CRC has them all.

The Middleburns and MTB c/set will have a wider Q than the TA but all have the rings you request.

aukray

Many thanks for all the helpful responses; the Middleburn/Stronglight doubles look possible.
I'm hoping to call at Spa Cycles in the next 2 or 3 weeks, so will ask their advice. I've read complaints from some people (on the CTC forum) that Spa can be rather 'brusque' in their diealings with customers, but I've never had a problem - and they do carry a lot of stock in addtion to the usual Shim/Camp stuff.

PeterBL

Also be ware of the fact that your FD is rated for min. a 50t big ring (curvature of the ring match the FD). It will probably work with a 42t ring, but shifting may not be as crisp. Unfortunately you cannot use a MTB FD instead with your shifters.

Another option (might be cheaper) is to get a 9-speed MTB RD from Shimano and a 10 speed MTB cassette from Shimano or Sram. You could go as low as 36 (is guess) at the back. The price would be bigger jumps between gears.

PS: generally I like you idea. The jump between 34 and 50 is quite big, and for most of us non-racers, a 42-11 is a high enough gear.

maddog 2

I wouldn't go down the mtb FD route (and I've tried it...)

they don't match road STI shifters in terms of cable pull and they don't work very well on road rings IME, even small ones.

My wife runs 32/44 on a TA Carmina with a Campag CT compact mech. Shifts fine. The Campag CT mechs are the best for compact rings in my experience (and I've tried Shimano and SRAM).

The Duo is well built but doesn't shift well at all.

In my view, shifting is as much down to ring design as front mech performance, and the Duos rings are clunky.

Running a road FD with smaller rings can be fine. Don't worry about the smaller diameter.

dbassi

I've used a mtb double MTB chainset (44-29 from FSA) in two road bikes, with a campagnolo centaur and a shimano ultegra setup.
Both had a clamp type FD so no problem in lowering them.
Front shifting was OK.

simon_e

If you fitted a triple you would need to swap the front mech and STI, but it wouldn't affect the rear shifter.

Have you considered a cyclocross chainset (46/36)?

aukray

By far my preferred option is a double chainset with smaller (and closer) rings than at present - preferably something like 30/42. There have been some very useful suggestions here, but I need to be clear before buying a new c/set that the rings will be compatible with my 10-speed chain and cassette.

Ray

maddog 2

this will definitely work, as it's my wife's setup (set up by me 8) )

TA Carmina cranks with a 4-bolt 104mm BCD spider.

Small ring is a 32t Shimano MTB ring (XT I think)
Big ring is 44t MTB - this time a RaceFace I think

Runs on a 107mm Royce square taper ti BB, with a Campag CT front mech, tweaked to run with Shimano shifters (different cable bolt to alter the cable pull ratio)

Rear end is all 10 spd.

It is essentially rings 2 and 3 of a MTB setup (32/44), but with a narrower roadie chainline and Q.

IIRC the Q is 150mm (I think) - not measured it but definitely better than any MTB chainset setup I know of.

See http://www.specialites-ta.com/produits/ ... ls1_gb.htm

You could even go smaller on the small ring as Extralite do a special 30t ring for 4-bolts but it's a rare beast.

You could go cheaper with the TA Vega arms but the Q is a bit more, which may put you off. See the TA website.

The Stronglight Oxale is a cheaper option for sure and may well do most of the things my TA setup does. The market is tricky with respect to 'compact' compacts and it took a fair amount of trial and error to get a decent setup.

The new lot of 2-ring MTB chainsets offer some hope but their Qs are necessarily big and the FD issues aren't obvious for road STI.

I should now bath the children.....

aukray

Thanks, maddog, very informative - gives me a few things to think about.
I've never had problems with Q factor in the past, but haven't ridden long distances on mtb chainsets. I'll have a look at the Oxale (which comes with a nice small inner ring), but have read some disquieting reviews of the Isis b/b which it needs. Have never had any problems with traditional square tapered b/b axles - the Shimano UN52 has been on my Thorn for 12 yrs and done huge distances, including 2 PBPs - still runs perfectly.

Ray

maddog 2

A standard 110mm BCD compact goes down to 33t so my setup is quite a faff just to lose 1 tooth :roll: Had to be done though...

If you want it fairly low geared and much easier to build then just go 33t and use a wide range cassette.

9spd goes 11-32, 11-34 etc
10spd goes 11-28, 11-32 these days

andrew_s

If you want a double with a 30T inner, there isn't much choice.
110mm MTB standard drive stops at 33T
4 arm MTB stops at 32T

Velo Orange do a 46/30 double that's an imitation of the old Stronghlight 49D/TA Cyclotouriste, at a price. ($190 plus import costs)
http://store.velo-orange.com/index.php/ ... nkset.html

The Middleburn RS7 has a Compact Drive spider available (about £147 for cranks and spider from http://activesport.co.uk), plus the chainrings and bolts. The 94mm middle/outer is the same as the Oxale, down to 29T.

There are these DMR cranks if you don't mind an external bearing BB
http://www.cyclestore.co.uk/productDeta ... ctID=19930

There's the Oxale (above) that are Isis BB, which has a reputation for not lasting.


Otherwise, Stronglight 86mm bcd cranks (80, 99, 100) are no longer made & therefore hard to find, but go down to 28T as a double.
. http://cgi.ebay.co.uk/Stronglight-80-tr ... 0628933074


You could just fit middle and inner rings only to a 110mm bcd triple such as the Impact. It would look ugly, but that's probably what I would do if I didn't want to pay for RS7.

jazzkailey

Simon E's suggestion is worth looking into.

I run a 36/46 chainset on a 11-27 cassette. It gives me a better range of usable gears without having to keep swapping between front rings or ride on the extreme ends of the cassette. I find it a bind when I ride my 50/34 bike.

FSA make a good quality looking cyclocross chainset. I'm not sure if you would need a new front mech. Also be aware, if your bike has a braze on for the front mech it may not be low enough to allow a front mech to reach a 46 ring.

maddog 2

TA do a 94mm BCD 5-bolt spider too (to fit the Carmina/Vega)

So you could go down to 29t on that.

See http://www.sheldonbrown.com/gloss_bo-z.html for info on BCD and rings

aukray

It's taken me a while to address this problem, partly because it is only recently that I've taken the 'summer bike' out to play.

After consulting many people - including, incidentally, Spa Cycles who were extremely helpful and courteous on the phone - it seemed that, short of the expensive option of swapping the entire drive chain + the Sti levers, I probably needed to take a chance and see what might work. Eventually I bought a Tiagra triple 30/39/50 (£46.70 from Parker), which fitted in minutes to the existing Ultegra B/B cups, and which worked on the 2 smaller rings without further adjustment. It seems the Stis cannot be persuaded to change on to the outer ring - which is to be expected as they are intended for a compact double - but the changes are slick and accurate despite dire warnings from Shimano and various other people I consulted.

I now have a triple c/set on which I am unable to use the outer 50t ring, but what do I care, 39-12 gives me an 87.8" gear which allows me to go as fast as I want (or am able!) on the flat. Downhill is meant for freewheeling, isn't it? I've just done 60 miles on this set-up and am delighted with it. Further 'tuning' might be done by changing the inner 2 rings to different sizes (even down to 24t if the FD would cope), and I could possibly remove the unused outer ring and replace it with a neat looking chainguard shown on the Spa website - might save a few grams, and would allow me to lower the FD to nearer the prescribed 2mm above the outer - ie second - ring. In the meantime I'm pleased with an easier and cheaper option than I thought possible. Not a solution for the purists, I guess, but it works extremely well. Mt Ventoux here I come!

Now, I have this little-used Ultegra 6700 34-50 chainset .... what am I bid?

John.T

You can certainly go down to a 26 granny ring. A friend has done just that on an Ultegra triple set-up. It all works fine.