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Old 12-22-08, 03:18 PM   #1
kilcoleman
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Advice on crankset/freewheel setup

I recently read the following thread about a crankset setup and am looking for some further advice for my specific goal of building an electric assist commuting bike (Bionx system) with three chainrings and a 7 speed Shimano freewheel. http://www.bikeforums.net/archive/in.../t-377250.html

The thread discusses a 52/42/26 crankset. I would like to use a similar crankset with a 13 - 15 - 17 - 19 - 21 - 24 - 28 7 speed freewheel on a Surly Long Haul Trucker frame that I intend to build up. (The link to the frame specifications for the Surly is http://www.surlybikes.com/longhaul.html )

Here are some of my questions:
1) Can a Sugino XD300 or XD600 crankset be setup to use 52/42/26 chainrings? If not, can someone please recommend a brand/model suitable for the Surly frame?
2) What front and rear derailleurs would work for this setup?
3) What shifter should I use (mounted to a flat handlebar)? (would a downtube shifter be more appropriate?)

Thanks...
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Old 12-22-08, 04:33 PM   #2
Gonzo Bob
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1) Sure. They are both 110/74mm BCD triples. 110mm BCD rings can range from 33T to as large as 60T. I don't know the availability of ramped and pinned 52 and 42 rings, though, if that's important to you. 74mm BCD rings can range from 24T to about 32T or so.

2) Road triple should handle the front just fine. Road is better than MTB since MTB FD's are typically made for big rings of 48T and smaller. According to the specs, a Shimano road rear derailer won't handle the setup. The specs for Shimano road long cage are 27T max cog and wrap capacity of 37. You have max cog of 28T and total wrap requirement of 41T. A Shimano MTB rear would handle it just fine, though.

3) MTB shifter on flat bar would work for the rear. I think there are issues using an MTB shifter for a road front derailer, though, but there are solutions (I just don't know what they are).
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Old 12-22-08, 07:05 PM   #3
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I had this bike set up with a Sugino XD-600, a Shimano 105 FD and MTB 7 speed shifters. The experts will tell you this won't work, but it shifted flawlessly. Somethimes you just need to try it and see what happens. It's more fun than listening to the experts.

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Old 12-22-08, 10:19 PM   #4
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Thank you both for your suggestions. So now that I know it can work and based on your advice Gonzo Bob I checked out Jensonusa's website and found a Shimano Dura-Ace FD-7700 front derailleur on sale for $40. Do you think this will work?

For the rear derailleur I found a Shimano Deore XT M771 rear derailleur but should I go with the GS or SGS version. I assume the SGS has a longer cage. Is this suitable?

For the shifter will the Shimano Dura-Ace SL-7700 9-SPEED (see http://www.jensonusa.com/store/produ...ed+Levers.aspx ) levers be suitable or do you know an alternative shifter that would work?

Dirtdrop, what are the models of the shifter and rear derailleurs that you are using?

Thanks again to you both for your advice so far.
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Old 12-23-08, 06:19 AM   #5
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For a crankset, you'd only need to swap the little ring on this one which would make the final price considerably cheaper than the Sugino and you'd have ramped and pinned rings: http://greenfishsports.com/product/3...ack-175mm.html

For a wide-range triple and relatively wide range cassette, definitely use the SGS long cage MTB rear derailler.

For shifters, if you were ok with using downtube shifters set to friction, they'll work with any derailler (front or rear) or any cassette/freewheel configuration (5, 6, 7, 8, 9, or 10 speed). As long as the number of speeds are matched, almost any (excluding some Dura Ace stuff) rear shifter will work with any rear cassette/freewheel. The front is more tricky as has been mentioned because of the different pull ratios between MTB and Road style but a front friction shifter mounted on the downtube or bar end solves all of those problems.
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Old 12-23-08, 10:55 AM   #6
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FD-7700 sounds like for double chainsets. Shimano road FDs for triple usually end in "3" like FD-7703. The FD-7703 would work great.

For rear derailer, go with the super long cage SGS. The GS only wraps 33 teeth (from techdocs.shimano.com) and you need (52-26)+(28-13) = 41. The SGS will wrap 45.

For shifting, if you're fine with down-tube friction, any shifter that has friction mode will work. But 8sp shifters may actually index OK on a 7sp cassette since the spacing is really close (4.8mm for 8, 5.0mm for 7). I have friends that use 8sp brifters on old 7sp drivetrains. If you can't find 8sp shifters, you could also try this alternate cable attachment to make 9sp shifters shift 8sp spacing. http://www.sheldonbrown.com/dura-ace.html#indexing

But one thing you might look into is shifters for the flat bar. Trigger shifters usually have indexed front which may not work well with a road FD (but then again as Dirtdrop said, they may work flawlessly) but twist shifters often are available with friction front which work with anything. Here are a couple...
http://www.jensonusa.com/store/produ...ifter+Set.aspx
http://www.jensonusa.com/store/produ...ifter+Set.aspx
Note: When looking at SRAM shifters, skip the 1:1 ESP ratio as they won't work with Shimano (or get an SRAM 1:1 ESP rear derailer if you get 1:1 ESP shifters).

EDIT: I think if you get the SRAM MRX set, you get an indexed front. But it looks like you can also buy separately and get a friction front. http://www.jensonusa.com/store/produ...p+Shifter.aspx

Last edited by Gonzo Bob; 12-23-08 at 11:13 AM.
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Old 12-23-08, 11:10 AM   #7
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Quote:
Originally Posted by Dirtdrop View Post
I had this bike set up with a Sugino XD-600, a Shimano 105 FD and MTB 7 speed shifters. The experts will tell you this won't work, but it shifted flawlessly. Somethimes you just need to try it and see what happens. It's more fun than listening to the experts.

Truer words were never spoken!

I can't tell you how many times I have put together bikes that worked great after being told it wouldn't work.

Of course, this is easier if you work in a shop where you can just put a part back on the shelf if it doesn't work. Civilians don't want to pay for things they don't need so there's more financial risk in experimentation.
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Old 12-23-08, 03:25 PM   #8
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Gonzo Bob, I checked out the FD-7703 and it says it is a size 31.8mm. Is this to do with the size of the seat tube it is being attached to? If so, I think the Surly frame needs a size 28.6mm or is there some kind of adapter available?

Joejack951, I appreciate your suggestion on the alternative idea for the crankset as it would make sense to get a ramped and pinned system. However it seems difficult to find with a crank shorter than 175mm and also there are some discouraging reviews at http://www.roadbikereview.com/cat/dr...1_2491crx.aspx . Unless you have some ideas for an alternative triple I think I'll stick with the Sugino.

Thanks for all the advice on the shifters. I'll look into your suggestions and I may choose to play it safe and go with the down tube shifters. I agree with the idea of just trying out different configurations but as has been mentioned, I'm not in a position where it's easy to return things if they don't work out!
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Old 12-23-08, 05:23 PM   #9
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Quote:
Originally Posted by kilcoleman View Post
Joejack951, I appreciate your suggestion on the alternative idea for the crankset as it would make sense to get a ramped and pinned system. However it seems difficult to find with a crank shorter than 175mm and also there are some discouraging reviews at http://www.roadbikereview.com/cat/dr...1_2491crx.aspx . Unless you have some ideas for an alternative triple I think I'll stick with the Sugino.
When reading through those reviews (which I did before buying the same crank) I came to the conclusion that every complaint either had to do with a bad installation (crank coming loose, not shifting properly) or abuse (complaints of chain jamming between rings when shifting while pedalling hard. duh, don't do that. or bent chainrings which is probably just sloppy handling of the bike).

The crank arm length is something that you can't do much to change though so if 175 is too long, you're out of luck. Over the summer, they had 172.5mm sets in silver for only $50 - 10% which is when I picked up mine.
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Old 12-23-08, 05:50 PM   #10
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Originally Posted by kilcoleman View Post
Gonzo Bob, I checked out the FD-7703 and it says it is a size 31.8mm. Is this to do with the size of the seat tube it is being attached to? If so, I think the Surly frame needs a size 28.6mm or is there some kind of adapter available?
Ah, so that's why they're on sale - limited sizes. They have the 7703 in braze-on mount and you could get a braze-on adapter (basically a clamp to mount the derailer to) for 28.6mm. The Shimano braze-on adapter is not for 28.6 but the QBP (Problem Solvers) is. Or you could go with a 6603, or 5603, or 4503, or R453.
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