Front Derailleur Clamp Issues - Tyre Clearance

arlowood

Just started building up my PX Pro Carbon frameset which has been sitting around in the garage for a couple of months.

I have a nice set of handbuilts from Malcolm at Cycleclinic based on Miche hubs and Archetype rims. I was hoping to get away with running Michelin Pro4 Endurance (700 x 28c) and was quite relieved to see that the clearance on the front fork



was fine since I don't plan to run guards or do a lot of wet/crappy road riding with it.

The rear seat stay bridge clearance is also acceptable tho a little tighter



However a problem has arisen in a more unlikely area. My Shimano 105 groupset came with a braze-on front derailleur so I ordered the band-on adapter from Planet X as the Pro Carbon frame does not have a pre-fixed FD mount. The problem I now have is that the clamp bolt for the band-on adapter is offset and when the FD is lined up correctly the clamp bolt ends up very close to the rear tyre



I may get away with it but I'm a bit worried that the tyre may deform sufficiently to catch the end of the bolt with the expected consequences.

Do any of you guys know of an alternative adaptor that where the clamping bolt is not offset. I thought of ditching the braze on FD and ordering a band-on one instead but looking at the images online it appears that the band on Shimano FD's also have an offset clamping bolt.

mr_evil

You might try just filing the bolt down. It looks like you could take a couple of millimeters off it, and remove the sharp edge.

Different clamps have the bolt in different places. For instance Shimano clamps put it further around to the side. You can also get some that have no bolt at all, like the ones from KCNC. If that's still not enough, there are carbon clamps that don't even have a hinge, and are really thin, but they are more expensive and less stiff.

arlowood

Mr Evil wrote:

You might try just filing the bolt down. It looks like you could take a couple of millimeters off it, and remove the sharp edge.

Different clamps have the bolt in different places. For instance Shimano clamps put it further around to the side. You can also get some that have no bolt at all, like the ones from KCNC. If that's still not enough, there are carbon clamps that don't even have a hinge, and are really thin, but they are more expensive and less stiff.

Thanks for these suggestions. I had trawled around after my post and found examples of the third type you mention
eg

https://www.bike24.com/p292041.html

but I'm not quite sure how good this type might be.

I do like the look of the KCNC ones so I might order one of those - at £10.50 it's not a big gamble.

In the meantime I will have a go at reducing the length of the bolt - I bought a 32tpi hacksaw blade to cut the steerer tube so that should do for shortening the bolt hopefully

JesseD

For the sake of a tenner I wouldn't bother filing it down, I would go straight to the KCNC clamp, not worth the risk of shredding your tyre then having to replace both the tyre and the clamp which I am guessing would come to significantly more than £10.50.

daniel_b

JesseD wrote:

For the sake of a tenner I wouldn't bother filing it down, I would go straight to the KCNC clamp, not worth the risk of shredding your tyre then having to replace both the tyre and the clamp which I am guessing would come to significantly more than £10.50.

Me too, keep the other one in your spares bin.

dj58

Put a thicker washer/s under the head of the bolt to decrease the amount of thread protruding through the nut and coat the threads with Loctite blue.

svetty

The clearance all round is pretty tight TBH - stones could easily get wedged there. That frame really wasn't designed with 28s in mind - I have 2 in the family of bikes I look after - I'd just stick on some 25s I think.

arlowood

DJ58 wrote:

Put a thicker washer/s under the head of the bolt to decrease the amount of thread protruding through the nut and coat the threads with Loctite blue.

Yes that was one of my first thoughts but my local hardware shop (one of the old school ones where you can actually buy single screws and washers if you need to) couldn't help. The washers have obviously to fit a 4mm allen bolt but they also have to be flush with the head of the bolt to allow the bolt to seat properly in the recess on the clamp. I'll keep looking but not sure if that type of washer is readily available.

JesseD wrote:

For the sake of a tenner I wouldn't bother filing it down, I would go straight to the KCNC clamp, not worth the risk of shredding your tyre then having to replace both the tyre and the clamp which I am guessing would come to significantly more than £10.50.

I was just about to pull the trigger on a KCNC clamp when I looked more closely at the images online. Although the clamping bolt would not be a problem, the actual thickness of the clamp itself may be so I'm still mulling that one over ATM. I think initially I'm going to have a go at reducing the size of the bolt with a bit of judicious hacksawing

Svetty wrote:

The clearance all round is pretty tight TBH - stones could easily get wedged there. That frame really wasn't designed with 28s in mind - I have 2 in the family of bikes I look after - I'd just stick on some 25s I think.

Yes I know using 28's is pushing it a bit and in an ideal world I would probably just fit 25's. However I have a brand new set of 28's that I bought earlier in a bundle deal and I love the plush ride they give on my PX London Road. I'm willing to risk the clearances until I'm proven either right or wrong