Surly Cross Check mtb & road mix up.

[Spibblo]

A question or two on the following,

Initially I built my cross check with all 9 speed mtb/trekking drive.
All modern 2012/2013 stuff including
Lx hubs and derailleurs
xt cassette 11-32
Deore 48/36/26 hollowtech 2 chainset
Dura-ace 9 bar end shifters (not modern or mtb like the rest but the 9 speed indexes perfectly with the later 9 speed (as we know) and the front shifter is friction so this works perfect too)

Now, here's where my problem starts.

I didn't like the Deore chainset with external bearings, I got something more traditional looking. A Stronglight Impact square taper chainset. Rings 48/38/28
This I think is predominantly a road/touring chainset.
Because the middle chainring is larger it fouled the chain plate on the front mech (trekking lx)
So I raised it up to clear but know I can't get the granny ring. I set it up properly but it won't drop back enough to pull the chain onto the granny- Is this because it's been raised or is it something to do with chainline?
Are road and mtb derailleurs set to work with the chainline particular to each- 45 road and 47.5 mtb?
I ask because I went with the recommended BB axle length of 110, which I now realize would be correct for a road bike with road matched drive train.

Should I now...

1. change the Front mech to a 105 or tiagra so it suites the 10 tooth difference between the middle and outer chainrings?

2. Fit a longer bottom bracket ie 113 to get the chainline to suit the mtb gearing at the rear? which would move the granny ring closer to the cage of the mech so it will shift.

3. Both 1 & 2

Many thanks,

Spibbs.

 

[JamesM]

Re:

The LX trecking front mech is designed for a 50mm chainline I think, which means it probably can't go in far enough. A road front mech should work but has a different cable pull ratio to an mtb mech, however as you are running a friction shifter that shouldn't be a problem. You could also take a look at one of the road flat bar series front mechs like an R443 (9 speed version) or R453 as these have the same cable pull as an mtb mech.

 

[Spibblo]

Re: Re:

The LX trecking front mech is designed for a 50mm chainline I think, which means it probably can't go in far enough. A road front mech should work but has a different cable pull ratio to an mtb mech, however as you are running a friction shifter that shouldn't be a problem. You could also take a look at one of the road flat bar series front mechs like an R443 (9 speed version) or R453 as these have the same cable pull as an mtb mech.

Cheers for your reply. Reckon your right about the chainline on the LX mech. They're also for 12t outer to middle chainring difference and I have 10t difference which is why I have the mech way higher than normal.

As I have 135mm spacing at the rear, to get the chainline right I'll need to move the chainset out either with a longer bb or drive side spacer. Then I'd need an mtb FD with 10t difference or maybe with the chainset set a few mm further out the existing lx mech would work ...?

I'm confusing myself now- it's late.

 

[Dead Rats]

Re: Re:

The LX trecking front mech is designed for a 50mm chainline I think, which means it probably can't go in far enough. A road front mech should work but has a different cable pull ratio to an mtb mech, however as you are running a friction shifter that shouldn't be a problem. You could also take a look at one of the road flat bar series front mechs like an R443 (9 speed version) or R453 as these have the same cable pull as an mtb mech.

I thought the Shimano front mechs you mention were designed to be matched to road specific flat bar shifters, rather than working with MTB shifters?

 

[JamesM]

Re:

They are really. They do work with MTB shifters but without the trim function of the flat bar series shifter you can get some chain rub. Spibblo has a friction shifter for the front though so all is good there.

 

[stewlewis]

Re:

I had the same on a couple of bikes.

1 bike ended up with tiagra triple chain set and then a tiagra front mech.
MTB shifters play nice with a FD-R443, the nexave FD that was on there didn't have the cage curve for the larger Tiagra outer ring.

The other inherited the 28.38.48 chain set and has as t401 nexave front mech that works a treat, even on a 9 SPD, I never found a cheap 600 series nexave f mech at the time, that's supposed to be 9 speed XT level whereas 400 series 8 SPD Deore level.

Anyway, 10 tooth difference, shimano = nexave.
With MTB shifters, as you're on friction it should work.

 

[Spibblo]

Re:

I've just had a fiddle with this. I checked the chain lines and front was about 45 rear 47 as you would expect road / mtb and yes the lx front be 50.

I found a larger BB in my spares box 113mm (next size up from my 110) I tried that and it's better. Not a problem now getting granny but the 48t is scraping slightly. Wierd thing is the bar end shifter seems to operate past it's own stopper a little, giving me the clearance- so no scraping (they meant to do that?) The chainline was straighter middle to middle.

I recon a 115mm BB would have this working perfectly. Cheaper and easier than buying and fitting another front mech, maybe.

Thanks for the replies, most helpful

 

[Spibblo]

Re: Re:

I've just had a fiddle with this. I checked the chain lines and front was about 45 rear 47 as you would expect road / mtb and yes the lx front be 50.

I found a larger BB in my spares box 113mm (next size up from my 110) I tried that and it's better. Not a problem now getting granny but the 48t is scraping slightly. Wierd thing is the bar end shifter seems to operate past it's own stopper a little, giving me the clearance- so no scraping (they meant to do that?) The chainline was straighter middle to middle.

I recon a 115mm BB would have this working perfectly. Cheaper and easier than buying and fitting another front mech, maybe.

Thanks for the replies, most helpful

No no no

It's true I needed the longer BB spindle but the reason I've had probs getting into the outer ring is because I had the shifter assembled incorrectly - what a div!
All done now and shifting perfectly. Yipp and indeed ee

 

[JamesM]

Re:

I love it when a plan comes together!!!

 

[Spibblo]

Re: Re:

I love it when a plan comes together!!!

Funny you should say that...

I think the old bb I used might be on it's way out. No play in it but I can hear a rumbling rhythmical (like a train :shock: ) either that or something to do with the new chain I just fitted the cassette's only done 100 miles tops and the chainsets new. This is all on the stand, need to road test it.