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Old 03-27-07, 10:07 PM   #1
robo
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How important are chainring pins and ramps?

I recently ordered a Sugino XD600 crank for my Bleriot build, and I'm anticipating that i may want to replace the 46 tooth big ring with something bigger, say, a 50 tooth ring.

The problem is that most of the 50 tooth rings i've been able to locate, that don't cost an arm and a leg, are 'plain' chainrings... in other words, they don't have the fancy ramps and pins and sculpted teeth etc. that most stock chainrings have.

Will this be a problem for shifting? The bike will have bar end shifters, which means that front shifting will be as primitive as it gets (ie. friction).

I assume that it won't be a big issue, but just wanted to check...



thanks
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Old 03-28-07, 12:17 AM   #2
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It'll work, but the shifting will be A LOT smother and faster
with a pinned and ramped ring. I have one bike with and
one bike without. Both with D.T.F. shifters. If it wasn't to keep
it as original as possible, I would never buy a ring that wasn't
pinned and ramped.

There again. It's only a 50T......
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Old 03-28-07, 02:16 AM   #3
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sydney used say it was all hype. He would then proceed to give an example of bikes he rode that worked great without it. I tend to agree with him. Most of my old 7 sp rides didn't ramps or pins and shift great. You start to notice problems as the chain gets narrower. That's why ramps and pins were put there. If your Bleriot is going to be a 9 sp, then you will notice a small difference.

IMO, buy the XD-600 with a 48 tooth big ring. Ben's Bike has them. Good luck

Tim
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Old 03-28-07, 03:58 AM   #4
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To me the key is the shifters. With friction shifting I'd say that a plain chainring will serve you adequately because you can overshift a little and tune it back. If you were using STI's or some kind of index shifter, I'd recommend using a chainring with the shifting aids.
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Old 03-28-07, 07:05 AM   #5
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On an occasion, I inadvertently ended up with a middle ring w/o pins and ramps. The shifting ended up being a mess, although I use gripshifts that principally allow you to overshift. After a couple of weeks I ordered a pinned ring and sold the other one to someone who did not care.
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Old 03-28-07, 08:25 AM   #6
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Quote:
Originally Posted by Retro Grouch
To me the key is the shifters. With friction shifting I'd say that a plain chainring will serve you adequately because you can overshift a little and tune it back. If you were using STI's or some kind of index shifter, I'd recommend using a chainring with the shifting aids.
+1

STI changed this. You need ramps and pins to make STI function as it was designed.
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Old 03-28-07, 09:19 AM   #7
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Quote:
Originally Posted by Retro Grouch
To me the key is the shifters. With friction shifting I'd say that a plain chainring will serve you adequately because you can overshift a little and tune it back. If you were using STI's or some kind of index shifter, I'd recommend using a chainring with the shifting aids.
Agree in part. With STI you need the pins and ramps to get clean reliable shifting. With friction shifters you don't NEED the shifting aids but they sure help.

An illustration: I had an old Suguino crank with flat chainrings on my beater bike that has a barcon friction front shifter. It shifted ok but was sluggish and reluctant if I tried shift under any load. When I upgraded another bike, I transferred its 105 8-speed crank (with all the ring enhancements) to the beater using the same shifter. The difference is very obvious and the new crank shifts much better.

So, no, you don't need modern chainrings but they are a major improvement even with friction shifting.
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Old 03-28-07, 09:21 AM   #8
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Quote:
Originally Posted by Retro Grouch
To me the key is the shifters. With friction shifting I'd say that a plain chainring will serve you adequately because you can overshift a little and tune it back. If you were using STI's or some kind of index shifter, I'd recommend using a chainring with the shifting aids.
+2. I have bar-end shifters on two of my bikes and don't really need ramps and pins, but they do make the shifts quicker on my Centurion (with XD2 48/36/26 crank).
If you've got a triple and rarely use the small chainring, you can get away with the middle ring without ramps and pins because the shifts are rare and you can put up with poorer shifting for a shift you rarely make.

But I do agree with HillRider, that ramped/pinned rings get you better shifting in any setup. It's just that a friction setup has more leeway for use with non-ramped/pinned rings.

Last edited by TallRider; 03-28-07 at 10:47 AM.
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Old 03-28-07, 09:37 AM   #9
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Hmm.. thanks. I ordered the crank last week, so i can't go back and change it to the 48 tooth model, although i could buy a 48 tooth Sugino chainring separately.

As a related question, does it matter what brand of chainring i get, or is any 'pinned and ramped' chainring with the right BCD going to work? (i assume it's not as critical as a Hyperglide cassette where each cog has a special orientation w.r.t. the others).
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Old 03-28-07, 09:51 AM   #10
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Oh, duh. I just realized that i just have to look for road compact chainrings, and there are plenty of reasonably priced pinned and ramped options at 50t and more.

Is there any reason a big ring designed for a road double won't work with a MTB triple, as long as the BCD is compatible?
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Old 03-28-07, 10:04 AM   #11
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Quote:
Originally Posted by robo
Is there any reason a big ring designed for a road double won't work with a MTB triple, as long as the BCD is compatible?
None at all. However, most current MTB cranks have different (smaller) BCD's than either standard or compact road cranks.
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Old 03-28-07, 10:04 AM   #12
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Quote:
Originally Posted by robo

Is there any reason a big ring designed for a road double won't work with a MTB triple, as long as the BCD is compatible?
No reason at all. I use the same 110BCD 50t ring on a road crank and an ATB crank.
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Old 03-28-07, 10:06 AM   #13
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Not to hijack this thread but to the OP: Did you come across any 130bcd 42/44/46 chainrings nonramped while you were browsing?
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Old 03-28-07, 10:18 AM   #14
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Quote:
Originally Posted by operator
Not to hijack this thread but to the OP: Did you come across any 130bcd 42/44/46 chainrings nonramped while you were browsing?
Sure.. like this? http://www.universalcycles.com/shopp...&category=2629

Non-ramped big rings seem to be made by lots of mfg's... i guess they're popular for SS bikes now.
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Old 03-28-07, 12:37 PM   #15
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Shimano usually says that the biggest chainring for their triple front derailleurs is 48t.
Also, there will be a big step between the 36t and 50t chainrings. It's not good for triples.
Shifting definitely won't be smooth.

What about a different cassette? There are some with the 11t smallest cog.
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Old 03-28-07, 12:43 PM   #16
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Quote:
Originally Posted by Barabaika
Shimano usually says that the biggest chainring for their triple front derailleurs is 48t.
Are you sure about that? The Ultegra triple crank comes stock with a 52t big ring, IIRC...

Quote:
Also, there will be a big step between the 36t and 50t chainrings. It's not good for triples.
Shifting definitely won't be smooth.

What about a different cassette? There are some with the 11t smallest cog.
Hmm.. i can't run an 11t cassette without modifying the freehub body, so i was hoping to put a bigger ring on the front instead...

Well, first i just need to see how the bike feels with the current gearing... which won't be for a few weeks at the least.
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Old 03-28-07, 01:00 PM   #17
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Quote:
Originally Posted by robo
Are you sure about that? The Ultegra triple crank comes stock with a 52t big ring, IIRC...
I thought that Bleriot was constructed to use mountain groups like Deore. The Deore derailleurs even have letters in the model names that indicate the maximum chainrings.
It should work anyway, just not very smooth. Front index shifting is always very difficult to adjust.
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Old 03-28-07, 02:16 PM   #18
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Quote:
Originally Posted by robo
I recently ordered a Sugino XD600 crank for my Bleriot build, and I'm anticipating that i may want to replace the 46 tooth big ring with something bigger, say, a 50 tooth ring.

The problem is that most of the 50 tooth rings i've been able to locate, that don't cost an arm and a leg, are 'plain' chainrings... in other words, they don't have the fancy ramps and pins and sculpted teeth etc. that most stock chainrings have.

Will this be a problem for shifting? The bike will have bar end shifters, which means that front shifting will be as primitive as it gets (ie. friction).
Bigger jumps always require a bit more skill. Without pins/ramps, you will need to ease off on the pedals more than you would if you had the pams and rins, but with a littl bit of practice the 36-50 shift should work fine. You will need to be ready for the cranks to suddenly slow down when the chain engages the big ring.

Actually, I think the bigger issue is going to be the 26 -> 36 shift. When you install the 50 tooth chainring, you will need to raise the front derailer by approximately 0.3183099 (1/?) inches.

This will move the inner plate higher up from the 36 tooth ring, causing deterioraion in the upshift from the granny.

If you haven't already bought a front derailer, I suggest that you look for a "10-speed" 105 or Ultegra unit...those are designed for a 14 tooth difference betwixt the middle and large chainring.

Sheldon "Don't Need No Steenkin' Rins Or Pamps" Brown
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Old 03-28-07, 02:45 PM   #19
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Quote:
Originally Posted by Barabaika
Also, there will be a big step between the 36t and 50t chainrings. It's not good for triples.
Shifting definitely won't be smooth.
I use an MTB triple with 48T, 32T and 22T. 48->32 is a bigger drop than 50->36. No shifting problems at all. However, I do run friction shifting (barend shifters) for the front der.
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Old 03-28-07, 07:16 PM   #20
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Quote:
If you haven't already bought a front derailer, I suggest that you look for a "10-speed" 105 or Ultegra unit...those are designed for a 14 tooth difference betwixt the middle and large chainring.
Thanks. I had actually ordered an Ultegra FD-6503 triple front derailleur for the bike.. not sure if it is '10 speed' though.. does this make any difference?
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Old 03-28-07, 08:27 PM   #21
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That front derailleur was indeed intended for the 14 tooth jump Sheldon mentioned.
39/53 chainrings have been standard for road doubles since before ten speed.
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Old 03-28-07, 08:44 PM   #22
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I'm running 26/42/52 chainrings on several road triple cranks and they shift fine. The 26 to 42 shift is a bit sluggish but I'm usually not in a rush for that one. The 42 to 52 and 52 to 42 shifts are fine.
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Old 03-29-07, 12:06 PM   #23
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Quote:
Originally Posted by reve_etrange
That front derailleur was indeed intended for the 14 tooth jump Sheldon mentioned.
39/53 chainrings have been standard for road doubles since before ten speed.
This is about triples, not doubles.

The problem shift is upshifting from the small ring to the 39; that's not an issue with a double.

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