Ultegra front mech close to rear tyre - normal?

luv2ride · April 2017

Just got a new bike advertised as being to take larger volume tyres (28-30mm). It's fitted with an Ultegra front mech (but non-series chainset, allegedly as the Ultegra chainset has 4mm less q factor, and may result in shoes fouling the chainstay). OE tyres are 28mm Durano's. I've noticed that, when in the big ring, the top of the front mech arm sits very close to the rear tyre:

The grub screw/bolt for the gear cable is only 5mm away from the widest point of the tyre wall. All my other bikes are Sram (Apex, Rival and Force, all 10 speed) and I see that their FD design has a much shorter arm, so fouling tyres isn't an issue in the slightest - in fact I have 38mm Hyper Voyagers on one bike running Rival.

Is it normal for the mech to sit so close to the tyre? I was hoping to (possibly) go up to 32mm tyres as the frame has the clearance, but also plan to upgrade the crankset to either Ultegra 6800 or perhaps Praxis Works. My concern is that with 2mm extra tyre width (one side), and 2 mm less q factor the same side, the culminating reduction in FD clearance may mean only 1mm between that and the tyre wall. Having not ever experienced this limitation with SRAM, I'm struggling to see why Shimano haven't designed out this potential compromise in their equipment, epecially given the burgeoning popularity with gravel riding with bigger volume tyres. Maybe this explains the rise of 1x in those circles?

Anyway, has anyone else experienced this? Cheers

P.s. I'd concede that front shifting seems better than any of my Sram set ups, possibly as a function of the longer arm in the mech, but I'm still surprised if improved shifting comes at the price of limiting tyre choice to such a large degree...

jgsi · April 2017

Seems ok to me... more worries by the pump action shotgun you've got attached.

Garry H · April 2017

Looks about normal to me.

Nice slipper.

luv2ride · April 2017

JGSI wrote:

Seems ok to me... more worries by the pump action shotgun you've got attached.

it's a temporary fixing as the normal pump placement (under bottle cage on downtube) doesn't work on this frame due to the wide tube profile - the pump and bracket hits the carbon. Rule # 30 may need to be observed on this bike...

GaryH: glad you're liking the post ride footwear 8)...the pipe is just out of shot

Garry H · April 2017

Luv2ride wrote:

GaryH: glad you're liking the post ride footwear 8)...the pipe is just out of shot

I do like a good slipper!

What bike is it?

trailflow · April 2017

I'm struggling to see why Shimano haven't designed out this potential compromise in their equipment

They have since redesigned the FD for the new R9100 groupset. It no longer has the long arm but it still feels light at the fingers and easy to shift. It should trickle down to the R8000 groupset when that gets released later this year. So just upgrade your FD if you have any issues with a 32mm tyre. But 5mm clearance should be plenty still.

I could be wrong but i dont think a crank with a narrower Q-factor means the chainrings sit closer to the frame. It's the arms that sit closer to the chainrings. So the position of the FD arm on the big ring will be the same on both cranks.

Garry H · April 2017

trailflow wrote:

I'm struggling to see why Shimano haven't designed out this potential compromise in their equipment

They have since redesigned the FD for the new R9100 groupset. It no longer has the long arm but it still feels light at the fingers and easy to shift. It should trickle down to the R8000 groupset when that gets released later this year. So just upgrade your FD if you have any issues with a 32mm tyre. But 5mm clearance should be plenty still.

I could be wrong but i dont think a crank with a narrower Q-factor means the chainrings sit closer to the frame. It's the arms that sit closer to the chainrings. So the position of the FD arm on the big ring will be the same on both cranks.

You're not wrong

luv2ride · April 2017

^That's good to hear (and in hindsight makes absolute sense that the QR factor would be influenced more by the design of the crank arms rather than the chainring distance relative to the frame). May order a 6800 Ultegra crankset this weekend in that event. Will be interesting to see if the shorter length arm on the 8000 series FD makes a big difference with bigger tyres fitted. Might stick to 30 mm max tyres until then.

GaryH: the bike is a 2016 Scott Solace disc, and they are plenty of pics on the Web with the 6800 cranks fitted, hence thinking of fitting some to help reduce the weight of the bike, as well as for the aesthetics.

I also notice a fair bit of chain rub when approaching (but not in) big/big on the cassette. Although my Sram kit admittedly has one less cog being only 10 speed, I never noticed chainrub on the front mech. This morning I found I could "trim" the Ultegra front mech with the left shifter, and found myself doing this a lot during the ride. It helped reduce the chain rub (though didnt remove it entirely) Forgive me, as I am from the world of Sram, but is this normal to have the trim the front mech using the brifters?

Bobbinogs · April 2017

Yes, using the trim feature is normal. One of the main attractions of electronic shifting is the auto-trim.

pblakeney · April 2017

Luv2ride wrote:

I also notice a fair bit of chain rub when approaching (but not in) big/big on the cassette. Although my Sram kit admittedly has one less cog being only 10 speed, I never noticed chainrub on the front mech. This morning I found I could "trim" the Ultegra front mech with the left shifter, and found myself doing this a lot during the ride. It helped reduce the chain rub (though didnt remove it entirely) Forgive me, as I am from the world of Sram, but is this normal to have the trim the front mech using the brifters?

You could also remove it by not crossing your chain to big/big.
Trim it or think of it as a warning.

chrisw12 · April 2017

Have a look at this thread viewtopic.php?f=40042&t=13079182 where we get into bit of a discussion about clearances.

Ultimately they're nice derailleurs but they've introduced more problems than they've solved. I hope the new dura ace ones work and the tech trickles down to cheaper prices

luv2ride · April 2017

chrisw12 wrote:

Have a look at this thread viewtopic.php?f=40042&t=13079182 where we get into bit of a discussion about clearances.

Ultimately they're nice derailleurs but they've introduced more problems than they've solved. I hope the new dura ace ones work and the tech trickles down to cheaper prices

Thanks, I did find that (after I posted :oops: ). It does seem an odd one, looking at the older style 10 speed mechs they also have shorter arms. Only an issue with bigger tyres I guess, but it's a shame its so restrictive.

Out again this morning and I do have to say the Shimano shifting is growing on me, very slick. Just a bit of bind constantly trimming, so I can see that the auto trim function on the electrunic groupsets is attractive. Seems an expensive fix to an issue that Sram doesn't have though!

BTW, I wasn't using big/big, but i noticed the chainrub started about 4 cogs out from the largest cog when in the 50t chainring. Needing to trim the the FD still seems a bit of a shortcoming to me, but in all other respects the Drivetrain seems pretty good

chrisw12 · April 2017

Yep, it is a shame, I looked at my new bike and thought wow I can fit massive tyres in there now, then realised that the front derailleur now becomes the limiter, something that would have never been a problem with the old style.

With regard to chain rub and trim I don't get any, I think because I've set the cable to enter the derailleur on the opposite side of the bolt to you and to what's recommended. I've then used the 6mm hex trick and a barrel adjuster to get quite a bit of extra tension on the cable. I've also messed with the cage angle a tiny bit.

What I'm trying to say, you can get rid of chain rub and not have to trim if you're willing to play around a bit. Of course if chain rub is really bothering you, you can take a set of pliers to the cage and widen the plates;)

luv2ride · April 2017

chrisw12 wrote:

With regard to chain rub and trim I don't get any, I think because I've set the cable to enter the derailleur on the opposite side of the bolt to you and to what's recommended. I've then used the 6mm hex trick and a barrel adjuster to get quite a bit of extra tension on the cable. I've also messed with the cage angle a tiny bit.

What I'm trying to say, you can get rid of chain rub and not have to trim if you're willing to play around a bit. Of course if chain rub is really bothering you, you can take a set of pliers to the cage and widen the plates;)

The pliers bit sounds a bit drastic, but think I'll have a play with the cable routing and limiter screws, cheers

luv2ride · May 2017

http://road.cc/content/tech-news/221907 ... a-groupset
So, more details on the new Ultegra groupset, with this:
"The mechanical front mech doesn't have the long arm of the previous version, a change that provides more rear tyre clearance."
There, knew I wouldn't be alone in thinking the current 6800 front mech was a bit of a hindrance...

Ultegra front mech close to rear tyre - normal?

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