Ultegra compact chainset - smaller chainring option?

[Ray]

I have a bike with Shimano Ultegra 6700 compact chainset (34-50) and matching STI levers and front changer. I don't like the 16t difference between chainrings, which necessitates at least a double change, and would also prefer some smaller gears for very long or steep climbs.

I see my options, in order of preference, as:

a) changing the chainset to something like a 30-42 double. Ideally, it would fit on the Hollowtech-type b/b, but this is not essential. Not sure what crankset would be suitable, but I guess there'd be TA chainrings available in 9/10 spd format? How do folk think the compact front changer, which is presumably really designed to run on a 48 or 50t outer ring, would cope with smaller rings?

b) getting a triple (M590 22-32-44 Hollowtech would fit, I think, although am not sure whether it would cause problems with my 10spd chain and cassette). And how might the indexed 'compact' front changer cope? Would I really need to change both the front changer and the left-hand STI lever?

I realise it's unlikely that there will be many people with direct experience of such a swap, but does anyone have thoughts on it, please?

Of course, one possibility might be to find someone with a triple set-up who'd like to swap it for my compact!

Thanks in advance

Ray

[mattsccm]

Just a thought. If you have two chain rings too close together in size the inner plate may well foul the inner ring when the mech is shifted to theouter ring. Depends on your mech. a triple one will be deeper.
I built a very useful halfstep/granny triple set up with a 52/48 38 set up. I liked the gears, the 48 was rather useful for much of my riding, the 38 for bail outs and the 52 for downs and nice flowing flats. All with a 8 speed cassette.

[glueman]

Beware of running out of chainstay/front mech space with smaller than normal chain rings.

[hamster]

You could run a Middleburn Duo chainset (29/42), or an MTB chainset (middle smallest is 32T).

The Duo is available to fit an ISIS BB as well as square taper.

I've run a Duo with a Campag Record road mech with no problems.

[Ray]

Thank you all for your helpful comments. I'll bear in mind the potential problems with using far smaller rings, and will look carefully at the Middleburn option - I wasn't aware of the Duo chainsets, which look very interesting.
The particular problem in changing to a different chainset seems to be that, certainly with MTB triples, they are designed for 9spd set-ups, which are likely to cause poor changing and meshing with my current 10spd chain and cassettes. I guess the best solution would be to go over to a full 9spd triple, including a change of front changer. STI shifter, and running gear.

Will need to think hard before such a radical and expensive option. As I said earlier, a full swap of chain, chainset, cassette and STI lever(s) with someone currently on a triple set-up might be a possibility. Otherwise, I may just decide to stick with what I have until either of us is worn out.

[Ray]

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. I thought that those who contributed to the original discussion might be interested in the outcome.

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 as suggested by Spa, and shown on their 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?

(also posted on BikeRadar forum)

Ray

[cycloret]

I've a road bike with an Ultegra Compact SL 50/34 with an 11/34 rear cassette and STI levers. Obviously I've needed a MTB rear changer. This gives a 119.5 to 26.3 range without much bother of lots of double changing.

I saw a suggestion that the chainset might take a 33 inner ring. I see Spa sell a 33T TA 110 BCD but I've not checked if this Ultegra Compact has this BCD inner. If fitted this would give 25.5, a small improvement.

[Ray]

Interesting to hear that the STi levers will work with a MTB rear changer. Gives a good range, but far too much top end for my needs.
I reckon the TA 33 ring would fit, but not convinced it would be worth it for one tooth difference.

Ray

[andrew_s]

Interesting to hear that the STi levers will work with a MTB rear changer. Gives a good range, but far too much top end for my needs.
I reckon the TA 33 ring would fit, but not convinced it would be worth it for one tooth difference.

Ray

The exception is that the new 10 speed MTB rear mechs are no good for road STI levers, as they've changed the cable pull for them.
You'd have to use a 9 speed MTB mech if your big sprocket was 30T or bigger.

[iandriver]

Perhaps a 10 speed double MTB chainset. SRAM do em:

http://www.rutlandcycling.com/29345/Sra ... -2011.html

Don't know how compatible it is with a road mech (i.e how spaced appart the rings are)

[cycloret]

To recap-
My road bike I referred to has Ultegra 10 speed STI levers controlling an Ultegra Compact SL 50/34 with an 11/34 rear cassette made by Mars. The Mars cassette was about £80 when I bought it from SJS, now it's crept up to £122.54p.
http://www.sjscycles.co.uk/mars-shimano ... prod13495/

My rear changer is an XTR (probably a M972 9 speed) which I bought a couple of years ago when making up this frame which I'd bought on eBay. I understand that Sram have brought out a 10 speed 11/34 cassette but it's not cheap.

It looks like Shimano is wanting to crowd out other manufacturers making compatible components. I suppose Shimano and Campagnolo have been playing this game for years, now it's for the 10 speed MTB market.

[james_b308]

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.

Have you tried a bar end shifter for the front derailleur? You may be able to find an individual shifter on Ebay for less than £20 or buy a set new and sell the second shifter.

James

[Ray]

Thanks again everyone for sharing your knowledge and ideas. There are some things manufacturers and catalogues can't or won't tell you.

I like James' idea - I have some old bar-end levers in the garage, so might be tempted to see whether the front changer will work on all 3 rings. Just for the hell of it, mind - I'm not convinced I'd be making much use of the 50t ring! I'd also need to be careful not to overstretch the existing rear changer - or swap to a long-arm or MTB rear changer.

Happy cycling

Ray

[bigjim]

So how much for the compact then?

[Ray]

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

So how much for the compact then?

Umm, haven't really got round to putting a price on it yet. Do you want to make an offer? It's done just under 1500 dry miles. Will try and take some pics by the weekend (and should really shift this to the For Sale section)

Ray