Author Topic: Which triple front mech 48T for an On-One Inbred?  (Read 580 times)

Which triple front mech 48T for an On-One Inbred?
« on: June 07, 2020, 10:51:17 pm »
I've been enduring an ongoing challenge in getting a front mech on my Inbred to behave nicely with a 48/38/28 triple chainset. I've tried a selection of front mechs from my spares box with varying degrees of success.  The best performer to date is an old Tourney mech but it's rear projection fouls the bottle cage on the seat tube so I'm looking for a better solution.  Are there any Inbred owners out there who've faced a similar challenge?
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #1 on: June 07, 2020, 11:32:41 pm »
I used to have an SLX one on my inbred, though I think maybe smaller chainrings.

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Which triple front mech 48T for an On-One Inbred?
« Reply #2 on: June 08, 2020, 05:16:13 pm »
IIRC Tiermat used a (Race Face?) MTB triple 44 with a 6700 Ultegra mech on InBred 29er...

Slightly confuzzled with 'Tourney fouling on...etc'. I'd be inclined to use a top swing, dual pull, low mount. Something like a Tourney TX800 or maybe an LX from the trekking group.

What shifters are you using?
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #3 on: June 08, 2020, 06:24:29 pm »
Slightly confuzzled with 'Tourney fouling on...etc'. I'd be inclined to use a top swing, dual pull, low mount. Something like a Tourney TX800 or maybe an LX from the trekking group.

What shifters are you using?

The Tourney I fitted has a low mount that cleared the lower bottle cage boss, but when I refitted the bottle cage it obstructed the mech when changing from the middle to small ring.

I've also tried a low mount microshift mech of the right but the clamp is too high and fouls the lower bottle cage boss.

For now I've refitted the original high mount Deore LX mech that was paired with a 44T triple, the clamp sits nicely between the bosses and after a bit of fine tuning it's working well between the outer and middle rings and just okay between the middle and inner ring. 

The shifters are Sram X5.
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Which triple front mech 48T for an On-One Inbred?
« Reply #4 on: June 08, 2020, 07:11:07 pm »
Quote
...but when I refitted the bottle cage it obstructed the mech when changing from the middle to small ring.

IMHO that sounds like the BB axle is too short.
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #5 on: June 08, 2020, 11:15:57 pm »
IMHO that sounds like the BB axle is too short.

Well yes, I did check the chainline this morning and it was a bit short (47mm) with the new chainset fitted, so I replaced the bottom bracket and managed to increase it to 50mm as specified for the Inbred frame.

However the Tourney, which now I come to think about it, came off a hybrid bike with a 73mm BB shell and a long axled BB, continued to hit the bottle cage.   Having checked the tech docs for the Deore LX it would appear that it is 48t compatible but has a 12t minimum capacity between top and middle rings.  This explains why setting the height of the fd correctly WRT the outer ring was causing the inner plate of the fd cage to foul the middle ring.

I've now set the height so that the inner plate just clears the middle ring and along with the new BB, things seem to have improved.  I'll take it for a test ride tomorrow to see how it works in practice.


Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #6 on: June 08, 2020, 11:17:42 pm »
Looking closer at mine I didn't have (? use) seat tube bottle cage.




Re: Which triple front mech 48T for an On-One Inbred?
« Reply #7 on: June 08, 2020, 11:39:01 pm »
Looking closer at mine I didn't have (? use) seat tube bottle cage.
There's certainly been a few variations in the build over the years... mine has all of the cable guides on top of the toptube and no pannier mounts.
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #8 on: June 15, 2020, 11:40:04 pm »
IMHO that sounds like the BB axle is too short.
Well yes, I did check the chainline this morning and it was a bit short (47mm) with the new chainset fitted, so I replaced the bottom bracket and managed to increase it to 50mm as specified for the Inbred frame.
...
I've now set the height so that the inner plate just clears the middle ring and along with the new BB, things seem to have improved.  I'll take it for a test ride tomorrow to see how it works in practice.

So, the "test ride" turned out be a complete lap of the Chilterns Cycleway and I'm happy to say that that the adjustments made to bottom bracket and deore lx fd worked well enough for me not to be in a hurry to fit the Altus FD-M313 that I bought after much perusing of the Shimano tech docs :facepalm:  In theory it's the perfect spec for an Inbred with a 48/38/28 chainset which may hopefully be useful for anyone wanting to "roadify" their Inbred :thumbsup:
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Gattopardo

  • Lord of the sith
  • Overseaing the building of the death star
Re: Which triple front mech 48T for an On-One Inbred?
« Reply #9 on: June 16, 2020, 12:11:59 am »
Can I ask which inbred?

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #10 on: June 16, 2020, 08:36:30 am »
Can I ask which inbred?
It's an early titanium 26er
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #11 on: June 16, 2020, 08:37:46 am »
Here's a photo
Most of the stuff I say is true because I saw it in a dream and I don't have the presence of mind to make up lies when I'm asleep.   Bryan Andreas

Re: Which triple front mech 48T for an On-One Inbred?
« Reply #12 on: June 16, 2020, 09:05:29 am »
FWIW the main problem with using a 12T min interval FD on a 10T interval chainset is that it has to be set ~4mm (2mm per tooth) too high above the big ring. This usually causes the middle to big ring shift to be less good than it should be, with overshifting off the big ring a possibility.  But I have used a comparable setup (actually a 10T min FD with a 6T interval) for many tens of thousands of miles without it killing me.

FDs can be finicky little  blighters, to the extent that on some bikes I will plan other aspects of the build around an FD that fits rather than the other way round.

E-bay is full of obscure FDs from the last 30-40 years; at one time 10T interval FDs were common on MTBs; I'd suggest an LX mech from the early 90's but for the fact that the top pull variants usually have a clunky cable run that sticks out well to the right of the seat tube.

cheers

vorsprung

  • Opposites Attract
    • Audaxing
Re: Which triple front mech 48T for an On-One Inbred?
« Reply #13 on: June 16, 2020, 12:19:03 pm »
I've been enduring an ongoing challenge in getting a front mech on my Inbred to behave nicely with a 48/38/28 triple chainset. I've tried a selection of front mechs from my spares box with varying degrees of success.  The best performer to date is an old Tourney mech but it's rear projection fouls the bottle cage on the seat tube so I'm looking for a better solution.  Are there any Inbred owners out there who've faced a similar challenge?

No, my Inbred is single speed!!

Why go against nature? 
Audaxing Blog follow @vorsprungbike on