Question re big cog "Shimano - Mega Range - Super-Low 14-34T" on Electra Townie 7D Cruiser

[Mike160304]

I have not ridden this bike yet. Please see the 3 photos. There are 6 moderately spaced gears and one "Super-Low" gear.

I know what they are trying to achieve, but does the massive gap between gear 1 and gear 2 increase the risk of the chain coming off?

Photo 3 shows damage possibly caused by the chain coming off?

For me, if the chain comes off once, that is once too often, and it is dangerous.

Yeah, I know, I am a natural worrier.
All the best,
Mike

 

[Big John]

Make sure the adjustment screws are done properly and you shouldn't have a problem. Mega range have been out for years and I've not had any problems in the past. Set the screws wrong and the chain will come off. Simples.

 

[Mike160304]

Make sure the adjustment screws are done properly and you shouldn't have a problem. Mega range have been out for years and I've not had any problems in the past. Set the screws wrong and the chain will come off. Simples.

Thank you, very helpful. I don't have any bicycle maintenance notes later than the 1980s, could you recommend anything? Or is it best to search on YouTube? I could ask Trek whether they have anything, I guess.

 

[T4tomo]

No greater risk. can be chattery getting onto 34T particularly if you leave it late to change 2->1 and the chain is under lot of tension. the other way 1->2 is no risk of falling off, it will just drop onto the 2 cog like any other.

as above the top adjusted screw dictates whether chain comes off or not, regardless of cog sizes

 

[Ajax Bay]

You'll be fine. This is a widely used 7sp freewheel.
https://brilliantbikes.co.uk/sprockets/1192-shimano-mf-tz500-7-speed-freewheel-14-34t-megarange.html
The 'dropping chain' risk can be reduced to ALARP by ensuring the limit screws are correctly set (as John says).
Gear ratios: https://www.gear-calculator.com/?GR=DERS&KB=40&RZ=14,16,18,21,24,28,34&UF=2185&TF=90&SL=2.6&UN=KMH&DV=teeth
The 1980s book will actually be more useful (for this) than a later book!
Richard's New Bicycle Book (<£3) is a great read and my 'go to' book. p324 and pp63-64 for freewheels.

 

[fossyant]

A bike is a bike, and guide on setting up gears applies, so don't worry. Just need to ensure the limit screws stop the chain going further than the 'end' sprockets.

 

[a.twiddler]

Megarange can be a bit Marmite with some hating the big jump but I've had several over the years and I like them. No more likely to unship the chain than anything else as long as everything is in alignment and the adjustments are OK as described above.

 

[wafter]

Aye, sounds worth winding in the high-end adjustment screw a bit to limit the RD's travel towards the rear wheel..

 

[Mike160304]

No greater risk. can be chattery getting onto 34T particularly if you leave it late to change 2->1 and the chain is under lot of tension. the other way 1->2 is no risk of falling off, it will just drop onto the 2 cog like any other.

as above the top adjusted screw dictates whether chain comes off or not, regardless of cog sizes

Great, thank you. I was imagining that the "getting onto 34T" might be "chattery" and "not leaving it too late" at the bottom of the hill (= keep tension low) sounds just right.

 

[Mike160304]

You'll be fine. This is a widely used 7sp freewheel.
https://brilliantbikes.co.uk/sprockets/1192-shimano-mf-tz500-7-speed-freewheel-14-34t-megarange.html
The 'dropping chain' risk can be reduced to ALARP by ensuring the limit screws are correctly set (as John says).
Gear ratios: https://www.gear-calculator.com/?GR=DERS&KB=40&RZ=14,16,18,21,24,28,34&UF=2185&TF=90&SL=2.6&UN=KMH&DV=teeth
The 1980s book will actually be more useful (for this) than a later book!
Richard's New Bicycle Book (<£3) is a great read and my 'go to' book. p324 and pp63-64 for freewheels.

WOW, not so much a reply, more a way of life! I shall really enjoy exploring all those links, many thanks!
But what is ALARP?

 

[Mike160304]

WOW, not so much a reply, more a way of life! I shall really enjoy exploring all those links, many thanks!
But what is ALARP?

A bike is a bike, and guide on setting up gears applies, so don't worry. Just need to ensure the limit screws stop the chain going further than the 'end' sprockets.

Thanks, that is very helpful!

 

[Mike160304]

Megarange can be a bit Marmite with some hating the big jump but I've had several over the years and I like them. No more likely to unship the chain than anything else as long as everything is in alignment and the adjustments are OK as described above.

Thank you, it's so good to hear from so many actual users!

 

[Mike160304]

Aye, sounds worth winding in the high-end adjustment screw a bit to limit the RD's travel towards the rear wheel..

Thanks, it is great to get so many helpful replies!