On One Pompino owners...

I like the bb routing, nice... I'd go straight for 42t ring, that will put your middle gear at 70gi which is usually the of the peg gear ratio for a reason :)

that seems like quite an extreme jump, keeping in mind I will be using this for loaded touring. I take your point though, maybe i'll meet you half way and go for 39t ;-) With fewer gears it does become a bit of a guessing game to get the right balance

8 speed is plenty.

I've not looked at your ratio's but my 8 speed Alfine has the same range as my 3x9 geared bike... Remember that although people call it a 27 geared bike, lots if those gears are actually the same and plenty of others won't be used at all (big ring with biggest half of the cassette or granny ring with smallest part of the cassette)...

Personally I'm more likely to get off the bike and push than go into a sub 30gi gear, but it depends on the individual I guess.

Just run into a MAJOR fuck-up with my Pompino build, just as I was expecting to be riding it.
LBS called to tell me that the 4-arm square-taper MTB chainset I intended to use (with 42T inner and 46T outer rings & a Surly Dingle rear end setup) sticks out way too far to get a decent chainline.
On a 107mm BB, it's too far out, and on a 103mm the crank bottoms out on the frame before it's tight.
The chainset I'd intended to use was a rather obscure Cyclone-branded item that allowed the mounting of outer rings in the middle position - something most Shimano stuff hasn't done for years. This is the chainset (with 46T ring):

Is there a 4-arm (104BCD) chainset out there with the same capability but narrower Q-factor?
Truvativ spring to mind, but I've no idea about what's what in their product lineup. I can go external BB if required.

I might consider downsizing the whole thing to 38T / 42T too - I need a 4-tooth difference between the two rings up front.
Any help much appreciated.

I'm confused by your comment about outer rings on the middle, can't you do that with all cranks? Or do you mean it's supposed to give you clearance to run massive chain rings on the middle ring? Because I would have thought that would be dependant on the frame and how big the crimps on the chain stays were?

Just run into a MAJOR fuck-up with my Pompino build, just as I was expecting to be riding it.
LBS called to tell me that the 4-arm square-taper MTB chainset I intended to use (with 42T inner and 46T outer rings & a Surly Dingle rear end setup) sticks out way too far to get a decent chainline.

This is going to be an issue whatever cranks you use, once you have the inner ring clearing the chainstay the outer one is bound to be 5mm or so further outboard. Measure the actual chainline, then re-space and re-dish the rear wheel to line up the centre of the Dingle with the centre of the chainrings. Chances are you won't have a perfect chainline on either combination, because the gap between the rings is probably bigger than the gap between the sprockets, so the best you'll ever manage is to have the same misalignment in both gears. You can actually get a perfect chainline on a 2×2 drivetrain by carefully respacing a double-fixed hub and using two conventional sprockets.

Also if you do this it removes the limits of using a dingle, namely you can select what ever cog combination you wish. So you can choose smaller cogs and make your chainrings smaller too. So they won't interfere with the chainstay.

Thanks for the info - I wasn't aware you could fit two single cogs (and presumably some sort of spacer) onto a fixed hub. Unfortunately I'm stuck with my $50 Surly item in the short-term. I'm going to head out to a shop that deals with s/h MTB parts this morning and see if I can't find a cheap 38T ring and another lower-profile crankset to mock up.
Re-dishing the rear wheel will be an absolute last resort.
Has anybody on here ever set up a 120-spaced Pomp as a Dingle Fixed?

Thanks for the info - I wasn't aware you could fit two single cogs (and presumably some sort of spacer) onto a fixed hub.

I'm talking about a double-fixed hub, i.e. one with threads on both sides. Ideally one with a 45mm default chainline, then you move it sideways 2.5mm to give chainlines of 42.5 and 47.5, which line up with double chainrings.

Re-dishing the rear wheel will be an absolute last resort.

I'd regard it as first resort, since a handful of axle spacers and a bit of spoke-key twiddling is much cheaper and faster than other trial-and-error methods of sorting out the chainline.

The rear hub is a Formula / Origin8 Double-Fixed item, with a 42mm chainline according to Sheldon.
I appreciate that a frame doesn't really have a chainline, it merely supports (or doesn't support) the chainlines of the crank and hub respectively.
I have zero wheelbuilding experience, if it came down to it I'd get the LBS to re-dish it for me. In the short term though, I just need to eyeball a few other MTB chainsets just to see if the one I've hung onto has an unusually wide chainline.
I can always go down the Road Double (or even BMX?) route after that if required.

What made me think 'MTB cranks are fine on Pompinos' was this bike which is running a 4-arm crank, 36T ring in the Middle position, and seemingly has plenty of clearance.
I'm now beginning to wonder if Gonz's bike is a 135-spaced Pomp? Is there any way to tell?

I'm confused by your comment about outer rings on the middle, can't you do that with all cranks?
No, particularly not Shimano. Don't know about other brands.

Or do you mean it's supposed to give you clearance to run massive chain rings on the middle ring?
Yes.

Because I would have thought that would be dependant on the frame and how big the crimps on the chain stays were?
It is. The 42T ring placed on the inside does touch the chainstays before I can get a good chainline with the rear end.

Hey guys I have a problem as well and I was hoping I could get some advice here... I just installed a miche primato bottom bracket (68 x 107) in combination with a Miche Advanced crankset. The problem is that the crank arms hit the frame when spinning. Is there any quick fix or am I doing something wrong? Thanks in advance.

Do you have the issue with just one crank, or both? Or do you mean the spider hits the chainstay, which is relatively common. If the latter, it's pretty straightforward to move the Miche BB to the right, you need a spacer under the drive side cup if you have one of the later flanged ones.

Hey guys I have a problem as well and I was hoping I could get some advice here... I just installed a miche primato bottom bracket (68 x 107) in combination with a Miche Advanced crankset. The problem is that the crank arms hit the frame when spinning. Is there any quick fix or am I doing something wrong? Thanks in advance.

Sounds like you need a longer spindle? On-One have said to me that they advise a 113mm spindle to clear they stays, but I'm sure ppl here are running different setups...

Do you have the issue with just one crank, or both? Or do you mean the spider hits the chainstay, which is relatively common. If the latter, it's pretty straightforward to move the Miche BB to the right, you need a spacer under the drive side cup if you have one of the later flanged ones.

Sounds like you need a longer spindle? On-One have said to me that they advise a 113mm spindle to clear they stays, but I'm sure ppl here are running different setups...

Thanks for the quick replies :). Both arms hit the frame when they are tightened so I guess I'll need a longer spindle then. Miche sells a 115 mm one... Should I get it or would you guys recommend something else?

Get a Shimano BB-UN55. If you only need a smidge of extra a 110mm will do, but 113mm is also available. When you're going to a longer axle (i.e. you already know the crank bosses are going to clear the cups) I recommend getting a 73mm shell version and stealing a 2.5mm spacer from your LBS, as that gives you wiggle room.

A quick reality-check at the used-parts LBS tells me that MTB cranks of any kind just won't work with a 120-spaced Pomp.
I'm looking at 130BCD Road Doubles now, I should be able to throw together a fairly cheap test setup by finding a decent s/h 53/39 chainset and ditching the 53T ring.
Scored a 43T 130BCD ring for $12, that gives me my 4-tooth difference required for the Dingle cog.
Fingers crossed.

Can I please ask what crank / BB / chainring setup is on the following bikes?

JB's blue one:

Jet's white one (running a 40T ring):

Woodz's white one:

Trying to get my head around what size the largest ring that can be run on the inside-position of a Road Double chainset is.

Mines a 40t MTB ring on a SRAM apex crank

Thanks for the quick reply Jet - is the Apex crank on a GXP external BB?

Yep, just the standard one

Now ordered my Pompino frame. I specifically stated for them to check I get one without a rear cantilever hanger prior to posting it out - I'm not holding my breath though.

Can anyone tell me the distance between the top of the seat tube extension and the bottom of the top tube (on a large frame)? A little worried my cut-down Thomson is going to be too short.

Can anyone tell me the distance between the top of the seat tube extension and the bottom of the top tube (on a large frame)? A little worried my cut-down Thomson is going to be too short.

Mine's a Large, here's a pic.

I didn't know you could spec them without the hanger tbh, I though all Larges had them.

Thanks for that, certainly seems like my seatpost is going to be on the very limit.

I've emailed On-One about the hanger and they told me that the frames don't have one. Plenty of photos suggest otherwise though.

I am running 113BB with MTB cranks albeit using the granny chaining instead of the middle and outer one and I have a perfect chainline. Hope this helps. Are you running a FD on your setup?

A quick reality-check at the used-parts LBS tells me that MTB cranks of any kind just won't work with a 120-spaced Pomp.
I'm looking at 130BCD Road Doubles now, I should be able to throw together a fairly cheap test setup by finding a decent s/h 53/39 chainset and ditching the 53T ring.
Scored a 43T 130BCD ring for $12, that gives me my 4-tooth difference required for the Dingle cog.
Fingers crossed.