# Internal gears for my commuter--1st 100 miles on SRAM S7



## Reynolds531 (Nov 8, 2002)

I recently converted my commuter bike from derailleur gears to a 7 speed internal gear using a SRAM Spectro S7 hub. The bike is an old filet brazed Chicago Schwinn Sports Tourer. I use it about 1200 miles/yr for short commutes running errands, riding on gravel rails-to-trails paths, leisurely day tours with my wife, and any riding in bad weather or the dark. These are my initial impressions after about 100 miles.

I purchased the hub from Airbomb for $129.33, the twist grip gear shifter was $34.44, and shipping was $8.07 for a total of $171.84. I got the version with no brakes, which has a stainless steel shell. Since there was no dish, building the wheel was easy. Installation of the hub and shifter was straightforward and easier than setting up an indexed derailleur.

It’s heavy. It weighs in at 1714 g, or 3.75 lbs. Removing the old freehub and cassette, the rear derailleur, the front derailleur, 5 links of chain, two front chainwheels, and barcon shifters then adding the S7 hub and shifter resulted in a net weight gain of 2 lbs. This doesn’t matter to me for this Old Schwinn—it has a solid steel chromed kickstand and chromed steel fenders. The weight gain was from 30.5 lbs to 32.5 lbs. 

The overall gear range is 303% in the steps of 57%, 68%, 81%, 100%, 124%, 148%, 174%. The gear jumps are pretty big. I ride quite a bit of single speed, so it’s not a problem for me. My bike is geared 48/23 for a gear inch range of 32 to 98. With the S7, I can maintain a cadence between 77 rpm and 95 rpm for any speed from 7 mph to 28 mph. The lowest practical speed is 4 mph at a cadence of 42 rpm. The highest practical speed is 35 mph at 120 rpm. I rarely ride at either of these extremes. In a paceline the big gear jumps might be a pain. For the way I use this bike, it has not been an issue.

I found the following SRAM Spectro S7 mechanical efficiencies from the rec.bicycles.tech google group. I have not been able to confirm them with a primary reference: 1 - 93%, 2 - 93%, 3 - 96%, 4 - 97.5%, 5 - 95%, 6 - 93%, 7 - 92%. I usually use gears 4 and 5 over the speed range of 12 to 19 mph. In these gears I don’t notice any efficiency loss compared to when the same bike had the derailleur system and power transmission is very smooth. In gear 2, and especially in gear 1, the power transmission is not as smooth—some vibration of gears meshing can be felt. I don’t know if the low-gear efficiency loss is significant. When I’m going up a grade where I need a 32 inch or 38 inch gear, it always feels like a have a flat no matter what bike I'm on. If I kick it up into 6th or 7th it means that I'm going down hill or with the wind, and efficiencies are hard to perceive. Power transmission in high gears is very smooth.

Shifting is perfect when pedaling is easy going into a higher gear. When shifting to a lower gear, nearly all force must be removed from the pedals for the gear to engage. It won’t shift under any significant load. Also, when shifting from 5th to 4th there is a slight neutral feel or slippage of about 1/16th of a crank turn. I’ve never had an instance when it wouldn’t shift or when it shifted on its own. I feel completely secure standing and pedaling with maximum force in any gear. I weigh about 185 and have pretty good strength.

Construction appears to be very rugged and the Spectro S7 has a very good reputation for durability and reliability. However, if something breaks parts will not be available at the LBS in the U.S. Field repairs seem unlikely. 

Overall I am very satisfied so far. I like having bikes that are significantly different from each other, and the Spectro S7 gives my Schwinn a different look, feel, and function than any of my other bikes. I’ll report again at about 1000 miles.


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## Henry Chinaski (Feb 3, 2004)

Nice report. Will be curious to hear how it holds up.


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## brianmcg (Oct 12, 2002)

Nice review. I have been thinking of doing something like this in a build for my wife. Thanks for the report.


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## MB1 (Jan 27, 2004)

Interesting, very interesting.


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## Reynolds531 (Nov 8, 2002)

*Correction on weight*

The version I'm using without brakes is mere 1556 kg. It was the coaster brake model that weighed.in at 1714 g, Knoweing that it's 158 grams lighter than I thought will really help on my next big climb.


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## fbagatelleblack (Mar 31, 2005)

*Photos, please!*

Sounds like a very cool build.

- FBB


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## Reynolds531 (Nov 8, 2002)

*Dirty pics*



fbagatelleblack said:


> Sounds like a very cool build.
> 
> - FBB


Sloppy weather, dirty bike, dirtier garage floor. Frame is 26" c-t seat tube, even though it looks smaller. Low bottom bracket gives a shorter head tube. The filet brazed Schwinn is built like a tank. Brazing is ground nice and smooth where you see it, but it is sloppy everywhere else. This is a 1971 model. Not much original left except brake calipers, frame, fork, headset, seatpost and the world's sturdiest chrome-plated kickstand.


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## fbagatelleblack (Mar 31, 2005)

Reynolds531 said:


> Sloppy weather, dirty bike, dirtier garage floor. Frame is 26" c-t seat tube, even though it looks smaller. Low bottom bracket gives a shorter head tube. The filet brazed Schwinn is built like a tank. Brazing is ground nice and smooth where you see it, but it is sloppy everywhere else. This is a 1971 model. Not much original left except brake calipers, frame, fork, headset, seatpost and the world's sturdiest chrome-plated kickstand.


Is that a Super Sport? It is the only model I know of that fits all the descriptions, but I did not think they were out in 1971. It is likely, however, that I am misinformed on the subject. In any case, gosh-and-golly would I like to get my hands on one of the 26" fillet-brazed, 4130 Schwinn frames! I have been looking (halfheartedly) for a while now! Got a spare one sitting in your garage you want to sell cheap?

We've discussed the Super Sport frames quite a bit over at:

http://sports.groups.yahoo.com/group/Bicycle_Restoration

One guy just spent quite a bit of time and money assembling a super-ultra-lightweight build on a Super Sport frame. I think he got the bike weight down to 18.sumptin!

Schwinn buff extrordinaire Bob Hufford has been know to lurk on this list. It would be interesting to get his take.

Nice build! I really like the way you set it up! Does the frame have a BMX-sized BB shell? Did you have to use an adapter kit to mount the crank?

Thanks!

Forbes


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## Reynolds531 (Nov 8, 2002)

*Top of line Schwinn except Paramount*

The Sports Tourer was one model up from the Super Sport. It had a nice alloy 3 piece cotterless crank with 54-36 chainrings and a 14-34 rear freewheel to give the widest gear range of any production 10 speed. It has forged dropouts with an integrated derailleur hanger. Bottom bracket threading was standard. I simply installed a 68 mm X 113 mm Shimano UN 53 bottom bracket and got the chainline within 1 mm. I had to respace the rear dropouts to 130 mm to fit in the Spectro S7. The rear cog is asymetric so you can flip it over and adjust the chainline by a few millimeters.

http://www.geocities.com/sldatabook/detail7074.html#1971sporttourer


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## fbagatelleblack (Mar 31, 2005)

Reynolds531 said:


> The Sports Tourer was one model up from the Super Sport. It had a nice alloy 3 piece cotterless crank with 54-36 chainrings and a 14-34 rear freewheel to give the widest gear range of any production 10 speed. It has forged dropouts with an integrated derailleur hanger.


Did the Super Sport have stamped dropouts?

Thanks,

FBB


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## BobHufford (Dec 4, 2004)

fbagatelleblack said:


> Did the Super Sport have stamped dropouts?


It did after early 1970 ... prior to that it had forged Huret dropouts.

Bob


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## dlenmn (Mar 28, 2006)

fbagatelleblack said:


> Is that a Super Sport? It is the only model I know of that fits all the descriptions, but I did not think they were out in 1971. It is likely, however, that I am misinformed on the subject.


http://www.geocities.com/sldatabook/detail7074.html#1971supersport

Good place to get information.

EDIT: Never mind... I should have read the other posts first...


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## harlond (May 30, 2005)

I'm resurrecting this thread to ask Reynolds531 how the hub is holding up after three years, if you don't mind. Thanks.

Edit: Never mind, found your 10 month update. Question answered. Sorry for the revival.


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## Reynolds531 (Nov 8, 2002)

harlond said:


> I'm resurrecting this thread to ask Reynolds531 how the hub is holding up after three years, if you don't mind. Thanks.
> 
> Edit: Never mind, found your 10 month update. Question answered. Sorry for the revival.


 You just had to remind me of this fiasco! The end of the story is that I did get the little plastic part shipped from England, but I had ruined the hub by riding without it. The wheel went into the trash can and I re-built the Schwinn with period correct-parts.


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## Mr. Versatile (Nov 24, 2005)

Is that period correct plastic tape? It hurts my hands just looking at it. I never had a Sport Tourer, but I did have a Super Sport of ~ 1970 vintage.


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