RX100 with 12-23 and Biospace 42-52 to lower gearing suggestions

[albion]

Recently I have been using my old steel bike and whilst in love with the bike, especially Biospace I still need to lower the gear.

Has anyone changed a similar setup with success. My flat bar bike is 11-34 and 24-32-42 yet Biospace seems to some how work to my benefit so I'd prefer to stay with that egg shaped chainset, if possible.

 

[raleighnut]

Recently I have been using my old steel bike and whilst in love with the bike, especially Biospace I still need to lower the gear.

Has anyone changed a similar setup with success. My flat bar bike is 11-34 and 24-32-42 yet Biospace seems to some how work to my benefit so I'd prefer to stay with that egg shaped chainset, if possible.

You could change the rear cassette/freewheel but you would then probably need to change the rear mech to a long cage version, the 105 long cage would be my choice, in order to accommodate the larger rear cogs. I may well be out of date but I seem to remember that only the outer ring is egg shaped.

 

[albion]

Being a 42 I always assumed it is egg shaped, that being the minimum Biospace for 130mm.
SeldonBrown says I can use a 38 'round' but am quite reticent about doing that.

 

[RecordAceFromNew]

Being a 42 I always assumed it is egg shaped, that being the minimum Biospace for 130mm.

Why not go large at the back then? Even if the RX100 rear mech was a short cage it should still handle 28T without fiddling, and I don't think an egg shaped front ring would make much if any difference to rear mech wrap range.

 

[albion]

Well, I found I had a standard non Biospace 39-52 and as that fitted fine I gave it a run today.

Those 3 less teeth smoothed the hills out but I really noticed I slightly bounce at the end of the stroke.
The incredible thing about the Biospace is that at the end of the stroke everything seems to slow resulting in no whiplash effect, exactly as reported by Sheldon Brown.That is fabulous for the hips.

Barring a placebo delusion they are a brilliant design. Maybe they only failed because of the 'exclude everyone else' patent.
Anyway, after todays ride, I'll get hold of a 28T. Hopefully that will be optimum.
If any manufacturer is reading, if the patent has ended, get manufacturing !

As a point of note, I got a horrible thigh cramp tonight, something I've not had since Biospacing. Coincidence maybe. I did 55 miles rather than my more usual 45 miles for the time of year.

 

[Smurfy]

There exist other more modern replacement chainrings that will probably give the same effect as Biopace (provided they are installed in the correct orientation).

Try having a look at Rotor Q, as these have a multitude of drillings, so that you can fine tune the orientation.

 

[sidevalve]

I have the same front and I fitted a 28 rear - result bliss. [and county durham aint flat].

 

[eck]

Hey albion. I have a pair of Shimano Biopace rings that were on a chainset I got from a mate. 40 and 52t, I've never used them, and they seem hardly worn. I think they may be steel and not alloy but, if they are of any interest, you can have them for the cost of postage.

 

[albion]

I think that might work perfect and it does seem the 40 was in steel, which for me is maybe preferable anyway.
Being practical rather than weight conscious I do use steel rings on my hybrid.

 

[eck]

If you'd like them, does £3 to cover postage sound fair? If so, PM me your address and I'll get them off to you.

 

[albion]

Yes, I think I've PMed you.

 

[albion]

Thanks for posting though am still waiting at the mo.

I found an 8 speed 11-30T cassette fitted the 7 speed hub leaving off the 11T sprocket. As I was by then trying a standard 39-52T chainset its close to being right, though I have stayed well away from those steeper 20-25% West Durham hills.
The 42-52T Biopace I have wouldn't be the worst thing in the world, possibly acting like a 39T at the horizontal.

 

[albion]

I just broke my first ever spoke on my £34 ebay 531 bike. Likely down to the 30T rear increasing spoke stress.
I have just removed the round chainset and put back on the 42T-52T Biopace.

Thats spoke impact stress reduced but I now get the feeling the knee/hip (non bounce) benefit will more than disappear when a hill grind gets too slow a cadence.