Double Chainring & low Gearing

[gordon1664]

Setting up a touring bike for summer touring in the Alps with tent, panniers etc.
I've left gearing to the last but what I have is an 8 spd 11-32 cassette running through an
XTR rear changer, Tiagra front changer and 105 8 speed STI's up front.
I've still to buy cranks/chainrings.
To get the low gearing I want, I'm thinking rings of 46/30. I don't do triples.

A) has anyone experience of a set similar to this?
B) Presumably MTB cranks won't do, I'll need road cranks?
C) recommendations for best make of cranks and rings.

[mattsccm]

Might I suggest looking at Spa cycles for a selection of interesting chainsets. MTB chainsets will be ok but sometimes they are a bit wide and you have to play with chain lines. Thing is you may be limited then by what rings work in the middle position as your inner, unless of course you use the mid position as the outer. I reckon Spa would be the best way unless you have a selection of chainsets to play with.

[reohn2]

........To get the low gearing I want, I'm thinking rings of 46/30. I don't do triples........

I don't think you'll be able to get that combination to work satisfactory with modern chainset configurations.
You could buy Spa's own Impact chainset(triple),leave the outer ring off and use the 28-38 that it comes with and some spacers/washers in place of the outer ring,so the chainring bolts will tighten without fouling the chain.
Alternately they sell the cranks without rings,you could buy whatever rings sizes suit,say 30-42
and use spacers/washers in the same way.I think that's as close as you'll get to your original 30-46.
You'll most likely need a triple front mech to work with the small inner ring though.

[thirdcrank]

You can buy MTB doubles with very small rings (very small when compared with what seems to count as a touring double)

I don't know anything about them except that they look pricey and aimed at mountain bikers with oodles of £££

[tatanab]

B) Presumably MTB cranks won't do, I'll need road cranks?

Either/or it makes no difference.

As Thirdcrank says you can buy micro-compact (I think they call them) set ups by people like SRAM for MTB, but they are comparatively new and rather expensive. All the other suggestions are "buy a triple and leave the outer off" which is something that is needed because of the difference in PCD. I have 40/24 on a Campag triple with the outer replaced by a cyclocross bashguard because I could not cope with the appearance of spacers and so on. Possibly a cheap option is to buy one of these (size 44T) http://www.spacycles.co.uk/products.php ... 0s109p2188 and add an inner ring. It depends if this setup is one you want for a single trip or to keep - nothing to say you could not keep this chainset in a box until next time.

[Ayesha]

You've come to the right place.


With a shorter BB, you can get the two inside rings ( 22 & 32 ) of a MTB set to be the appropriate chainline for a Tiagra front changer.

What's needed is to get the middle ring of an MTB triple ( 50mm chainline ) to the chainline of a road double outer ring ( 43.5mm + 2.5mm = 46mm ). So take 4mm off the driveside of the BB.
I took the Dawes Giro BB down from 115 to 107.

To get the 44 ring onto this set-up, requires filing the seating Dia of the 44 ring until it sits on the middle ring seat; and installing a Dog Fang.

[rfryer]

I once bodged a road bike for a particularly hilly sportive. It has an Ultegra compact double setup on it. I just replaced the double chainset with a road triple. I couldn't get hold of any spacer washers, so I just slapped a second middle chainring on the outside, and had a 26-tooth granny ring.

I had to adjust the front dérailleur a bit, but I don't recall any major issues.

[531colin]

This keeps coming up....I searched on "alpine" and got this, but there will be others......http://forum.ctc.org.uk/viewtopic.php?f=5&t=71220&hilit=alpine

[Valbrona]

Setting up a touring bike for summer touring in the Alps with tent, panniers etc.

I've left gearing to the last.

I don't do triples.

Words of wisdom, eh.

[Alport]

Hello
I've been following this thread and others which have been linked elsewhere about the possibility of using double chainsets but with smaller rings. I've got a 52-42-30 triple Shimano 105 set in my box of left overs - I right in thinking that I could remove the outer and replace with a bashguard and then use with 105 STI double shifters?
All the bits date from at least 10 years ago - and I was wondering if I could make use of them on an old frame which just also happens to be taking up space in the shed!

[BertYardbrush]

This keeps coming up....I searched on "alpine" and got this, but there will be others......http://forum.ctc.org.uk/viewtopic.php?f=5&t=71220&hilit=alpine

Yes - that's my bicycle! I took it out the other day - it's my summer bike. I'm running 44/32 on the front and 28/11 on the back. The front changer, Shimano CX double with 105 STI shifters works really well. I have a Spa triple crankset using the middle and inner ring positions only. I have an outer ring in the middle position so the countersink is on the wrong side. I have had to use spacers to bring the chainrings closer together. I'm going to change the 44 to a 46 as it needs a bit more oomph at the top end.

Good luck with your build.

[531colin]

This keeps coming up....I searched on "alpine" and got this, but there will be others......http://forum.ctc.org.uk/viewtopic.php?f=5&t=71220&hilit=alpine

Yes - that's my bicycle! I took it out the other day - it's my summer bike. I'm running 44/32 on the front and 28/11 on the back. The front changer, Shimano CX double with 105 STI shifters works really well. I have a Spa triple crankset using the middle and inner ring positions only. I have an outer ring in the middle position so the countersink is on the wrong side. I have had to use spacers to bring the chainrings closer together. I'm going to change the 44 to a 46 as it needs a bit more oomph at the top end.

Good luck with your build.

Yes, on the Spa/Stronglight chainset there is normally a spacer between the spider and the middle ring, , otherwise big and middle are too close, and the chain drops between middle and granny.

[531colin]

Hello
I've been following this thread and others which have been linked elsewhere about the possibility of using double chainsets but with smaller rings. I've got a 52-42-30 triple Shimano 105 set in my box of left overs - I right in thinking that I could remove the outer and replace with a bashguard and then use with 105 STI double shifters?
All the bits date from at least 10 years ago - and I was wondering if I could make use of them on an old frame which just also happens to be taking up space in the shed!

well it sounds OK, but I don't know if you might need a slightly longer BB axle** to get the 2 inner rings of your triple where the F. mech. expects a double to be....chainlines are a pet hate of mine!! http://forum.ctc.org.uk/viewtopic.php?f=5&t=59701

** or a spacer behind the RH cup

[Alport]

Thanks both
I've still got the original BB - (5500) 118.5mm length. The FD though is a Tiagra double and not the original triple 105. I'll give it a go.

[BertYardbrush]

Thanks both
I've still got the original BB - (5500) 118.5mm length. The FD though is a Tiagra double and not the original triple 105. I'll give it a go.

I used a 113 BB offset with a spacer.