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'75 Sentinel Sophomore

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'75 Sentinel Sophomore

Old 10-13-19, 05:06 AM
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drker
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'75 Sentinel Sophomore

Thought it was similar to a vintage Schwinn so I bought it. One thing that I found surprisingly similar was the Chrome fork crown from Schwinn also fits the Sentinel fork.
What I am not so thrilled about is cleaning the Positron shifters. Haven't ever dealt with them till now.
Shimano - Positron instruction manual

Sentinel fork with schwinn chrome


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Old 10-13-19, 07:24 AM
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Despite the disparaging reputation, 1st generation Shimano Positron worked well and was straight forward to set-up. The critical issue is proper cable tension, since it is one continuous cable that operates in a double run, push-pull fashion, as there is no parallelogram spring. The cable length is also an issue, if it needs replacement. Most derailleur cables are too short, so you'll have to find a tandem cable or spice two together. Substituting modern compression free SIS cable housing would should improve things slightly.

I'd appreciate the frame serial number for my database. TIA.
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Old 10-13-19, 08:43 AM
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frame number

NA716786
Will this help identify the year the bike was made? The guy I got it from says its 40 years old.
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Old 10-13-19, 09:32 AM
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Originally Posted by drker
NA716786
Will this help identify the year the bike was made? The guy I got it from says its 40 years old.
I was hoping it would allow me to identify the manufacturer and date but it's not ringing any bells. Still, it's improbable that anybody would retro-fit Positron given it reputation and Positron was introduced for the 1975 model year, so it should be no older than that. Positron II, with the single push-pull cable was introduced for the 1977 model year but the original Postitron was still catalogued that year, so it could be 1975-1977. The front derailleur is hidden behind the crankarm but the cage looks like the revised Shimano design introduced for the 1977 model year on 400/500/Titlist. If so, there should be a date code on the back of the cage, consisting of two alpha characters. There may be a similar date code on the rear derailleur. The SR crankarms should also have date codes on the back, though the format will be different. Given the era, they could be alpha-numeric or open format numeric date codes. Pending your findings, I'm leaning towards a 1977 model. The S/N could certainly be reversed engineered to that date.
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Old 10-13-19, 09:38 AM
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Actually this set is on the rear.Alpha characters lok like AI

Will check the front

Last edited by drker; 10-13-19 at 09:42 AM.
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Old 10-23-19, 01:53 PM
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here are the updated picture





s
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Old 10-23-19, 06:36 PM
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https://www.ebay.com/itm/Vintage-Sen...p2047675.l2557

Another Sentinel bicycle, with a similar setup. Some connection to an American build source in the write up, which seems, to me, to have some dubious claims. Almost everything diamond (10 speed type) bike frame wise, in the 70's, was already being built outside of the USA, except for Schwinns. Wasn't it?

Last edited by uncle uncle; 10-23-19 at 08:37 PM.
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Old 10-23-19, 07:40 PM
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I'm trying to attach the image of a pdf from the back page of the owner's manual for a '76 Sentinel Whisper. Not having much luck. You can download the attachment to view it, though. The bikes were assembled in Chatsworth, CA from frames and components made in Japan.
Attached Files
File Type: pdf
76 Sentinel Back Page.pdf (110.2 KB, 23 views)
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Old 10-24-19, 06:08 AM
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Originally Posted by drker
Actually this set is on the rear.Alpha characters lok like AI

Will check the front
The rear derailleur is from September 1976. This is late enough in the year to be a 1977 model. Knowing this and looking back at the serial number, the frame appears to have been manufactured in January 1977 but I still can't tell you the manufacturer.
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Old 10-24-19, 07:03 AM
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Originally Posted by uncle uncle
https://www.ebay.com/itm/Vintage-Sen...p2047675.l2557

Another Sentinel bicycle, with a similar setup. Some connection to an American build source in the write up, which seems, to me, to have some dubious claims. Almost everything diamond (10 speed type) bike frame wise, in the 70's, was already being built outside of the USA, except for Schwinns. Wasn't it?
Actually, there was still quite a lot of bicycle (frame) manufacturing in North America during the late 1970s. Mass volume manufacturers still active in the USA included Schwinn, Ross, Huffy, Trek, Murray and Columbia. Canada had CCM, Procycle (Peugeot and Velosport), Raleigh and Victoria Precision. Bicycle production in the USA at the end of the 1970s was actually at about the same level as it was at the beginning of the 1970s. However, most of the domestic marketing brands were sourcing from Japan due to lower costs and by the end of the late 1970s Taiawanese souces were starting to be utilized for the entry level models.

The Ebay bicycle is interesting. The Eagle II rear derailleur and Front Freewheel crankset were both introduced for the 1977 model year. So it' should be no older than the OP's bicycle but the graphics look older. In fact, the graphics show the influence of Raleigh and Centurion. The frame itself looks very much like a Centurion LeMans, including the colour, head lugs, stay caps and rear dropouts. Hudson308 sent me some Sentinel serial numbers and two of them were consistent with that found on Centurion of the era. The Ebay bicycle may be manufactured by one of the same sources that manufactured Centurion.

Last edited by T-Mar; 10-24-19 at 07:10 AM.
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Old 10-24-19, 07:51 AM
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Originally Posted by uncle uncle
Another Sentinel bicycle, with a similar setup. Some connection to an American build source in the write up, which seems, to me, to have some dubious claims. Almost everything diamond (10 speed type) bike frame wise, in the 70's, was already being built outside of the USA, except for Schwinns. Wasn't it?
+10 to T-Mar, a lot of low end crap 10 speeds were being made in the USA during the 1970s such as Columbia, Huffy, and Murray. And by the late 1970s, Trek entered the market.
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Old 10-24-19, 02:31 PM
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That headbadge is what I would buy this bike for.
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Old 10-24-19, 06:49 PM
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Originally Posted by T-Mar
Actually, there was still quite a lot of bicycle (frame) manufacturing in North America during the late 1970s. Mass volume manufacturers still active in the USA included Schwinn, Ross, Huffy, Trek, Murray and Columbia. Canada had CCM, Procycle (Peugeot and Velosport), Raleigh and Victoria Precision...... In fact, the graphics show the influence of Raleigh and Centurion. The frame itself looks very much like a Centurion LeMans, including the colour, head lugs, stay caps and rear dropouts. Hudson308 sent me some Sentinel serial numbers and two of them were consistent with that found on Centurion of the era. The Ebay bicycle may be manufactured by one of the same sources that manufactured Centurion.
Good info everyone. I'm never sure if the Huffy's, Murray's, and Columbia's of the bicycle circles are party to discussions here or not, so again, I'm just going to politely abstain. The Trek entry level model I'm aware of, but it seems to be pretty rare (the only one I've ever seen was posted on this C&V forum). Anyway, on the Sentinel on the auction site... it says the bicycle was powder coated, so, it's also possible that the owner went with graphics that aren't anything remotely close to the originals (or maybe they did, who knows)...
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Old 10-24-19, 07:17 PM
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Originally Posted by uncle uncle
Good info everyone. I'm never sure if the Huffy's, Murray's, and Columbia's of the bicycle circles are party to discussions here or not, so again, I'm just going to politely abstain. The Trek entry level model I'm aware of, but it seems to be pretty rare (the only one I've ever seen was posted on this C&V forum). Anyway, on the Sentinel on the auction site... it says the bicycle was powder coated, so, it's also possible that the owner went with graphics that aren't anything remotely close to the originals (or maybe they did, who knows)...
The Ebay Sentinel is actually representative of the type of product that Columbia, Huffy and Murray were offering at the time. Thank-you for pointing out the powder coat, which I had missed. That would explain the discrepancy in the graphics. While the new decals are a legitimate Sentinel style (see attached photo), they may be an older style than appropriate for the bicycle.
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Old 10-24-19, 08:11 PM
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Originally Posted by T-Mar
The Ebay Sentinel is actually representative of the type of product that Columbia, Huffy and Murray were offering at the time. Thank-you for pointing out the powder coat, which I had missed. That would explain the discrepancy in the graphics. While the new decals are a legitimate Sentinel style (see attached photo), they may be an older style than appropriate for the bicycle.
https://vintage-centurion.com/literat...on_Catalog.pdf

The above photo showing another style of decals adds another visual connection to your "Centurion supplier may have been the same as Sentinel's" Theory. The lugs and decals do seem very similar between the two full bicycle suppliers (I know there is probably a better term for them, but it escapes me). Check out the orange colored, black decaled, Sports 10 model shown in the catalog link above. Maybe they shared a common frame supplier...
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Old 11-03-19, 05:28 AM
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I did ride the Sophmore to work at least 3 days. I think the positron shifter is effortless. Missed a deal on a whisper in my area. I was ready to get another Sentinel. I like the German made wheelset, derailer and Tourney/Shimano brakes. I do believe I would have a hard time finding the rear derailer dual cable housing if I needed it. Also like the heavy cables for shifting and brakes.Thanks for all your comments.
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Old 11-03-19, 06:10 AM
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Originally Posted by 3speedslow
That headbadge is what I would buy this bike for.
I was thinking the same thing.
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Old 02-08-22, 04:16 PM
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I owned a Sentinel Californian in the early 80's. It was purchased at a local department store (FedMart) in the San Fernando Valley. It appears the Sentinel factory was down the street on Mason. I'm thinking they may have offloaded much of their inventory prior to closing. I found the following link to a Sentinel Californian which had the exact same color scheme and decals as the one I owned. I notice in the pictures from the link that it has the Positron derailleur. The one I had in the early 80s had an entry level Shimano derailleur.

https://auctions.transitionaldesign....tails/25627517
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Old 02-08-22, 11:06 PM
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you mean "FedCo"?
I had a summer job assembling Sentinel bicycles at the Mason St. HQ in Chatsworth, with some fellow dudes form Chatsworth High (Go Chancellors!).
We worked in a big open warehouse that I think had been the Safeway supermarket (when I was a younger kid).
After 2 months, or less, the gig was done.
Very much a slice of "Licorice Pizza"...except even less glamorous.
(PS: "Licorice Pizza" was a chain of SoCal record stores...get it?)
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Old 02-09-22, 02:55 AM
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Sentinel Californian 1982
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Old 02-09-22, 03:02 AM
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unworthy - Thanks for sharing your story. I think I would have enjoyed working there as a junior high school kid. If my memory serves me well, the Fedmart I was referring to was located on the Southwest corner of Balboa and Nordhoff, it is now a Target store. I do recall the Fedco membership stores, I use to shop at the store located on Raymer. I remember the Sentinel had Rigida chrome wheels, DiaCompe brakes, Takagi cranks, Kenda tires. I want to say the price was a little over $100, definitely not over $200. I would ride that bike all over the San Fernando valley and visit all the bike shops, eventually buying a Nishiki Prestige in 1986 from Kellys Bikes on Woodly and Parthenia. Kelly was a character.... I still have the Nishiki and ride it regularly.
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