Downtube pip

[Mac_Mwnci]

Hello all.

Just want to double-check something. Have I fitted this correctly? (see pic) There's a 'pip' on the underside of the downtube to stop the gear lever band-on from slipping. At first I thought the band-on should sit 'on top' of the pip but I don't think it'll close that tightly. I'm guessing the two sides of the pip get wider down its length to deter the band-on from moving.

Advice greatly appreciated. I'd be distraught if it slipped and ruined the paintwork! :shock:

 

[pigman]

Re:

Yep, looks good, provided the pip lets you tighten up the clamp enough so that it's not a loose fit. If it is a loose fit, you need to move the clamp up, above but in contact with the pip.
Also if the pip isn't exactly in the middle, the levers may not be perpendicular to the frame

 

[Mac_Mwnci]

Re:

Phew - that's a relief I've added some electrical tape to the underneath of the clamp as well, just for good measure. Thanks for your reply!

 

[mdvineng]

I would remove the tape as it will be eaten through by the clamp and therefore loosen it. also the clamp should slightly forward of the pip and clamped around or near it.

 

[Mac_Mwnci]

Re:

Thanks. I fitted the tape to the underside of the clamp to minimise any scratching on the fresh paint job. If you look at the pic again you can see that the band-on is indeed clamped around the top portion of the pip, the pip's sides then are at such an angle that will deter it from sliding downwards. It's held fine since fitted now, including during a quick spin 'round the block'. As pointed out by 'pigman' the barrel adjusters (downtube adjusters) aren't 100% level though, something I might have to just live with.

 

[Midlife]

Sometimes the brazed on pip is offset so it catches just one side of the band when the shifters are dead level.

 

[Captain Stupido]

Hmmm... I'd be happier if there was a "pip" sat against the flat part of the band like in this picture...

In cases when it's a poor fit/match I've had problems with with band on shifters sliding down the top tube (and over the pip) while attempting to shift. It made a mess and I nearly fell off... The cables can exert quite a strong pull.

I'd also be worried that as fitted in your picture the "pip" is stopping you from tightening the clamp properly.

 

[Mac_Mwnci]

Re:

It looks to be pretty central. Just as I finish tightening the left side lifts a little. BTW, I usually tighten parts like this by feel, but recently bought a torque wrench (for one of my other bikes, a Croix De Fer 30). According to the Shimano docs, band-on mechs should be tightened to 5-7 N-m :shock: This feels like a lot when torquing so I went for 4 N-m. Any opinions?

The frame and forks were refurbished by Bob Jackson a couple of years back now. I went for the option of a frame pip as I planned to run it single speed*, but now I fancy a change. I've experimented with a 1x9 speed set-up, mainly using parts I already have, but couldn't get a decent chainline, so now I'm now just building it as a standard road bike, but with bullhorns instead of drops, and bar end shifters instead of STIs (brifters)

(*had three other road bikes at the time so built this one up to be a little different)

 

[Mac_Mwnci]

Re:

Bluetomgold - Yes, that's how I imagined it would work when I first looked at it. This pip is on the underside of the downtube though, as well as having a 'fancy' shape. I'm really worried about it slipping, given that *this* happened before the refirb (when the frame didn't have a pip at all)

and yes, I know I'd put the barrel adjusters on upside down - rookie mistake (and a long time ago now)

 

[Captain Stupido]

Re: Re:

It looks to be pretty central. Just as I finish tightening the left side lifts a little. BTW, I usually tighten parts like this by feel, but recently bought a torque wrench (for one of my other bikes, a Croix De Fer 30). According to the Shimano docs, band-on mechs should be tightened to 5-7 N-m :shock: This feels like a lot when torquing so I'm so for 4 N-m. Any opinions?

The issue isn't whether it's central or not, it's whether it will stop the band sliding down the tube when the cables are tensioned, especially if something goes wrong and you put more tension on the cables than you would in normal shifting, i.e. pressing hard at the end of travel, or if something gets stuck. When that happens the band can jump over the "pip" and make a mess. If the band is not flush against the pip you are asking for trouble, IMO.

I suppose a cable stop is under less stress than a pair of band-on shifters, but saying that I have had similar problems with similar stops sliding down the tube on hub gear setups... and having had problems before I always make sure this sort of thing is done up TIGHT.

That's my experience, but it's your bike. If it were me I'd think about flipping it 180 degrees and having the bolt at the top. Or even better use this sort of thing, much more secure, if a little modern looking:

https://www.ebay.co.uk/itm/On-Frame-Cab ... SwSQFaQ2-9