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-   -   Brifter + mtb front der' ? (https://www.bikeforums.net/bicycle-mechanics/923868-brifter-mtb-front-der.html)

thook 11-26-13 10:49 PM

Brifter + mtb front der' ?
 
Yes, I've ran searches, but I'm still confused. Everything I read says brifters and mtb/FD's are a no go, but then some still manage to make the combo. What gives? Is it something only doable with a top pull style derailleur?

Why? I have an early 90's Deore DX groupset on my 'cross build and would like to stick with it if at all possible. That includes derailleurs, crankset, hubs, and brakes. Right now I'm using some Deore XT thumbies that I dremelled out and mounted on the bar tops. But, the indexing is failing and I would really, really like to go with brifters....STI or Ergo. Kinda undecided on that part. Bar ends are out. The idea is nice, but my knees don't like them. Plus, well....you know.....brifters are just the bomb. I'd go with something like an early 90's 105 FD if I really hafta to make the brifter thing work, but I sure like my current kit. It all matches...hehehe. If the top pull mtb/FD would be what makes it work, though, maybe I could just find another Deore DX on ebay of the top pull variety?

If at all pertinent, my goal is setting up a 2x9 with a 42x26 up front and 11-34 in the back.

Andrew R Stewart 11-26-13 11:38 PM

Shimano front der cable pull ratios are different between road and mountain bike, but you know that. Not sure how far back in time this difference is valid. Also i believe that the cranks have slightly different ring C-C spacings, road and MtB. The thumb levers work well because the front is a friction unit.

Options- First would be Ergo with a JTech adptr for the rear. Front is not indexed and read with the Shiftmate works pretty well. Second would be bar end levers. Third might be trying a road front der with STI levers, being only a double crank the differences in stroke might not be enough to be a problem.

One issue is the 42 front big ring. Any road der will not have a good cage curve match to this small a ring. This aspect falls off around a 46 ring.

In the end you might just have to try and see with what ever combo you come up with. Andy.

fietsbob 11-27-13 12:03 AM

No guarantees.. give it a try.. no risk, no reward, etc.

thook 11-27-13 01:19 AM


Originally Posted by Andrew R Stewart (Post 16281866)
Shimano front der cable pull ratios are different between road and mountain bike, but you know that. Not sure how far back in time this difference is valid. Also i believe that the cranks have slightly different ring C-C spacings, road and MtB. The thumb levers work well because the front is a friction unit.

I wondered how far back the difference was valid myself. I'm still hoping someone can tell me. ;) Also, I did read about the difference in road and mtb cranks, too. Hrmph! Well, I have seen atleast one build wherein a fella was using a full, up to date XT mtb build on his Fargo; XT crankset and derailleurs with Sora brifters. 3x9, as I recall. Don't recall about any complaints with that system. I'll have to review, I suppose.

Options- First would be Ergo with a JTech adptr for the rear. Front is not indexed and read with the Shiftmate works pretty well. Second would be bar end levers. Third might be trying a road front der with STI levers, being only a double crank the differences in stroke might not be enough to be a problem.

I've read about the JTech, but I've also read about a simple cable rerouting at the RD with the Ergo and Shimano derailleur set up. But, what's this about the front not being indexed? Front Ergo shifters are friction? Did not realize that, if that's what you're saying. I'll have look up the Shiftmate. I've not heard of that.

Again, don't want to do the bar ends. I've ridden them once and was immediately turned off by my knees hitting them in certain situations. I'm sure I could adapt, but I'd just rather do brifters than have to deal with it.


One issue is the 42 front big ring. Any road der will not have a good cage curve match to this small a ring. This aspect falls off around a 46 ring.

Why would the cage curve matching up be a problem? I mean, if many road cranks are set up with a 52x42x30 and the derailleur shifts fine through all three rings, then what's the issue? Sorry.....I just don't understand.


In the end you might just have to try and see with what ever combo you come up with. Andy.

Right. I may have to. I just thought this might be something of a charted territory. I certainly keep looking into it, though.

Replies in red. Thank you!

thook 11-27-13 01:21 AM


Originally Posted by fietsbob (Post 16281909)
No guarantees.. give it a try.. no risk, no reward, etc.

Ha! Righto!

thook 11-27-13 01:35 AM

Okay.....here's a close example of what I'm shooting for:

http://velospace.org/node/19207

Note the mtb FD is an XT (top pull, perhaps)....probably suited to a 46t top chainring, I would guess? And, he's using a 42t top ring. Probably a road crank, though, huh? I wonder since I'm using a triple mtb crank and my idea is to simply drop the outermost ring, use a 42t ring in the middle position, maybe I could use different spacers for the 26t granny ring to bring the spacing between the two rings closer to road spacing??? Would this be on the right track in regards to the C to C issue?

Retro Grouch 11-27-13 07:44 AM


Originally Posted by fietsbob (Post 16281909)
No guarantees.. give it a try.. no risk, no reward, etc.

Not this retro grouch.

If I already own components, I'll bolt anything together to see if I can make it work to my satisfaction. If I'm buying parts, I'll hold out for stuff that's supposed to work together.

fietsbob 11-27-13 09:46 AM

Bar end shifters FTW ! (at least, on my rigs) friction, over pull-ratio compatibility issues..

GeoKrpan 11-27-13 10:11 AM

Integrated road shifters WILL shift a MTB crank BUT only between TWO of the rings, not all three.
Since you are planning to use two rings it will work perfectly.

I am shifting a three ring "trekking" crank, 48/38/28, with MTB shifters using a road triple derailleur, works perfectly.

thook 11-27-13 10:14 AM

Well, I won't buy anything until I can find out if I can make brifters work. If I have to go through a lot of trouble for sub par performance, I'll just look for some same era 105 parts; front der' and crankset. I have a wheelset I sometimes swap out with that have some 105 hubs. That'd be cool, too.

Incidentally, my current DX canti's have some wobble on the post. Doesn't seem to be the bushings wobbling on the posts, rather it seems the canti's are wobbling on the bushings. Is it time to replace the canti's? Is the pivot worn out? I've had these canti's so long I can't remember if the wobble is normal.

thook 11-27-13 10:17 AM


Originally Posted by fietsbob (Post 16282744)
Bar end shifters FTW ! (at least, on my rigs) friction, over pull-ratio compatibility issues..

Lol! Well, I am looking into the knees hitting the bar ends issue. Seems one internet solution may be to trim the ends of the handlebars, but I kinda hate to do that and find out it doesn't work.

thook 11-27-13 10:20 AM


Originally Posted by GeoKrpan (Post 16282858)
Integrated road shifters WILL shift a MTB crank BUT only between TWO of the rings, not all three.
Since you are planning to use two rings it will work perfectly.

I am shifting a three ring "trekking" crank, 48/38/28, with MTB shifters using a road triple derailleur, works perfectly.

Okay....now we're getting somewhere. But, I may still need to use a road derailleur? Will I need a triple FD or will a double work since I'm only using two rings? I'm guessing the FD capacity may be an issue, see. I think most double FD's have a 12 or 14t capacity, right?

GeoKrpan 11-27-13 10:32 AM


Originally Posted by thook (Post 16282885)
Okay....now we're getting somewhere. But, I may still need to use a road derailleur? Will I need a triple FD or will a double work since I'm only using two rings? I'm guessing the FD capacity may be an issue, see. I think most double FD's have a 12 or 14t capacity, right?

You don't have to buy ANYTHING, what you have will work fine.

I guess you will be mounting the 42 in the middle position so that it is adjacent to the 26. Try it, if it doesn't work, go with 42/32. 26 is very low.

The FD that you have will work fine. You will be adjusting the stops so that it only accesses two of the rings.

Wilfred Laurier 11-27-13 10:33 AM


Originally Posted by fietsbob (Post 16282744)
Bar end shifters FTW !


Originally Posted by thook (Post 16282877)
I am looking into the knees hitting the bar ends issue.

in my experience
it really isnt an issue

bar ends are not quite as ergonomically perfect as brifters
but knee strikes are so rare i cannot remember it happening to me
except maybe when straddling the top tube while standing on the ground

edit
as others have said though
you can make almost any shifter derailleur combo work well
if you have only two chainrings

Wilfred Laurier 11-27-13 10:36 AM


Originally Posted by thook (Post 16282885)
Okay....now we're getting somewhere. But, I may still need to use a road derailleur? Will I need a triple FD or will a double work since I'm only using two rings? I'm guessing the FD capacity may be an issue, see. I think most double FD's have a 12 or 14t capacity, right?

with 42 26 a mtb derailleur should work
although that is a pretty big jump in teeth

fietsbob 11-27-13 10:42 AM

a retroshift kit, http://www.retroshift.com/store/products/shifters/
putting the bar end lever on the front of the brake Lever [modified Tektro]
may be a suitable middle ground.
Shimano left shifters are friction on all their bar end sets.

thook 11-27-13 10:44 AM


Originally Posted by GeoKrpan (Post 16282933)
You don't have to buy ANYTHING, what you have will work fine.

I guess you will be mounting the 42 in the middle position so that it is adjacent to the 26. Try it, if it doesn't work, go with 42/32. 26 is very low.

The FD that you have will work fine. You will be adjusting the stops so that it only accesses two of the rings.

Right. 42t in the middle.

Yeah, 26t is low. I'd like to use a 24t, but I've done a 42t to a 24t jump on a 46/42/24 half step with friction shift up front. It's a doozy and I don't think it would index well. Some of the hills around here are just ginormously steep and sometimes long to climb. Most hills, though, I can easily pull with a 36t middle ring and 28t low cog. A really low "bale out" is nice because there's a lot of hills overall. It can be taxing after a 20+ mile ride. And, sometimes I'm just not up for it without a sufficient low.

thook 11-27-13 10:46 AM


Originally Posted by Wilfred Laurier (Post 16282935)
in my experience
it really isnt an issue

bar ends are not quite as ergonomically perfect as brifters
but knee strikes are so rare i cannot remember it happening to me
except maybe when straddling the top tube while standing on the ground

edit
as others have said though
you can make almost any shifter derailleur combo work well
if you have only two chainrings

I see.

Well, maybe the difference in our experiences lends itself towards top tube length. And, I use a pretty short stem.

thook 11-27-13 10:47 AM


Originally Posted by Wilfred Laurier (Post 16282946)
with 42 26 a mtb derailleur should work
although that is a pretty big jump in teeth

16t? Aren't many compact cranks like that? Like 50t outer ring and 34t inner?

Wilfred Laurier 11-27-13 10:51 AM


Originally Posted by thook (Post 16282990)
16t? Aren't many compact cranks like that? Like 50t outer ring and 34t inner?

you are right
although that is a jump from outer to inner
where the derailleur vertical movement is at its maximum

as the derailleur moves inward
the vertical movement for the same amount of horizontal movement
decreases

i have never tried it
and i would bet it has a 75 percent chance of working
but might be tough to get perfect

only one way to find out though

thook 11-27-13 10:52 AM


Originally Posted by fietsbob (Post 16282969)
a retroshift kit, http://www.retroshift.com/store/products/shifters/
putting the bar end lever on the front of the brake Lever [modified Tektro]
may be a suitable middle ground.
Shimano left shifters are friction on all their bar end sets.

Yes, yes.....I've looked at that option quite hard. But, for that kind of money, I'd just as soon get the brifters. Plus, I have small hands. Great for getting around engines, but not for some other things. I've read the throw on the retro shift can be tricky in certain gears.

fietsbob 11-27-13 10:59 AM

Shimano Front brifters just go Ka-Thunk , thats where the pull ratio issues happen..

Look back at past Posts , there are the 'it works' and 'it does not' camps for the will it work question .
I'm reserving neutrality.. ..:innocent:

Retroshift is a Cyclocross racer's Idea, tired of Breaking Brake levers, falling,
and getting mucked up in the Portland Oregon Mud.

you can mix the right Brifter.. Shimano, sells as an each for repairs,
For the left, you may go outside the Box.

thook 11-27-13 11:00 AM


Originally Posted by Wilfred Laurier (Post 16283009)
you are right
although that is a jump from outer to inner
where the derailleur vertical movement is at its maximum

as the derailleur moves inward
the vertical movement for the same amount of horizontal movement
decreases

i have never tried it
and i would bet it has a 75 percent chance of working
but might be tough to get perfect

only one way to find out though

Hrm. Well, if that big of a jump won't work, I have a 28t or a 30t ring I can substitute. Of course, it'd be a loss on the low gear. Maybe I could use a 40t top ring, instead. I rarely exceed 100 gear inches in use, anyway.

thook 11-27-13 11:07 AM


Originally Posted by fietsbob (Post 16283045)
shimano brifters just go Ka-Thunk , thats wqhere the pull ratio issues happen..

Look back at past Posts , there are the 'it works' and 'it does not' camps for the will it work question .
I'm reserving neutrality.. ..:innocent:

I do keep looking. It's a matter of keywords and resulting info, I suppose. And, then there's direct application.

thook 11-27-13 11:14 AM

Wait a sec.....back up. Andrew R Stewart said something to the effect of the Ergos not being indexed up front? Is that correct? And, the shiftmate...is that for the rear? Is that the JTek adapter?

Edit: Nevermind. The Shiftmate is the JTek adapter for the rear. Still....what of the Ergos and non indexing front? IF it's not indexed, that would nullify front end issues, no?


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