Bosch ALP smaller chainring

Darren Hayward

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Mar 25, 2015
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I'm looking at how to get lower gear ratios on my Cube Hybrid touring pro 2019. Its Bosch ALP is 38t front with an 11-42 ten speed cassette. I've found a 36t front chainring but I wanted a 34t really. Does anyone know of anywhere I could buy this from?
Many thanks



Darren
 

soundwave

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May 23, 2015
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i cant find a 34 anywhere.

they might be able to help find one tho.
 

Artstu

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I'm looking at how to get lower gear ratios on my Cube Hybrid touring pro 2019. Its Bosch ALP is 38t front with an 11-42 ten speed cassette. I've found a 36t front chainring but I wanted a 34t really. Does anyone know of anywhere I could buy this from?
Many thanks



Darren
Does it have a 4 bolt 104mm BCD ?
Gebhardt Singlespeed MTB or Road 3/32" 104mm BCD Chainring available in 34T

 

soundwave

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May 23, 2015
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Darren Hayward

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Mar 25, 2015
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Yes its (allegedly) a 104mm 4 bolt. This is what Evans directed me to, a 36t was the smallest they knew of;


I need to take the current one off and have a good look. Thanks for the excellent help.

An Explanation.
I'd like to ride Cheddar Gorge some time but its 16% at the bottom. A test ride showed I could get up the near 12% hill at Wotton under Edge but not the 13.7% back road up the same hill. There are numerous issues, not least of which is my big lumpy 110kg body. I also have problems with any sort of Toe clip. I have a 15" metal pin holding my right leg together and the surgeon did a good job of making my legs the same length but my right foot turns out slightly and with a Toe Clip my right ankle keeps hitting the crank arm. I can't retrofit a 2020 CX which leaves lower gearing as the next option to try.


Darren
 
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Gringo

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Jun 18, 2013
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if you can’t go any smaller on the front, go bigger on the back :p
i’ve recently put one of these on my 9speed analog bike and will be doing the same on my ALP cube in the near future ;) (l think you can go up-to 11-50)
 

Darren Hayward

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Mar 25, 2015
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Well this is a lesson in checking your (my) facts. I assumed Evans knew what they were talking about but neither they nor I did.

This is what's on my bike now

33527
 

anotherkiwi

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Jan 26, 2015
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You might get away with 4 links, I just lengthened a chain to fit my 46:11-42 up from an 11-34 cassette and used 8 links and it is a bit sloppy. 7 links would have been perfect...

if you can’t go any smaller on the front, go bigger on the back :p
i’ve recently put one of these on my 9speed analog bike and will be doing the same on my ALP cube in the near future ;) (l think you can go up-to 11-50)
Yes the 11-50 would be my first choice for a 1 X 9 setup. The cassettes aren't quite up to Sunrace quality but they aren't too bad, my 11-42 8 speed shifts nicely.
 

RobF

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Sep 22, 2012
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You could remove a few links if you are confident to do so.

But on t'other hand, provided the rear mech is not folded too far back on itself in top gear, why bother?
 

Darren Hayward

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Mar 25, 2015
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With a single on the front and a ten on the back there is quite a lot of bounce in the chain so I suspect taking out 4 links will be about optimal. I'm also wary of putting on a new chain that fits then ends up too long with a bit of stretch. Anyway, 32t chainring is on order. I'll update if anything interesting occurs.


Darren
 
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Darren Hayward

Pedelecer
Mar 25, 2015
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OK so I'm on holiday this week and I've fitted the 32t chainring and 165mm crank arms. I've now done some test rides. I went over to Golden valley and went up Beach hill (Oldland common, Bristol) which is 12.9% and I flew up it. A few days later I went to Wotton Under Edge (South Glos) and went up the back road to Cotswold Edge golf Club which is mostly 15% and I got up it ok. On the way back from Wotton I had my first ever touch of cramp but although it was only a 21 mile ride it was cold and I'd not ridden more than 5 miles for a month so I'm not going to read anything into it.
What is interesting is that I keep getting the gear symbol come up on my display because I'm in too low a gear. I've had that symbol before a few times but I'm now getting it a lot. I can see that the smaller crank arms might mean I'm cycling with a slightly higher cadence so in theory I'm a gear too low but its virtually every hill and slope I go up. My current thinking is that the gear algorithm Bosch use is a bit sensitive but it might be the lower gearing has thrown it off. Anyone have any thoughts on that?

Darren
 

sjpt

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Jun 8, 2018
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I have the opposite issue, it tends to think I'm in too high a gear because I get lazy and don't want to pedal very fast (and I don't want to pedal up Beach Hill either, but if I did it would be a very low gear even on and electric bike). I don't think it really thinks about the gearing, at least not directly. I guess that is just based on keeping to a cadence that the motor likes.

~~~

If you are up that way don't miss Pipley Barn Cafe right on the Cotswold Way next to the Lansdown Golf Club. It's opening hours are likely to be pretty erratic for the next few months though.

 

Darren Hayward

Pedelecer
Mar 25, 2015
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I have the opposite issue, it tends to think I'm in too high a gear because I get lazy and don't want to pedal very fast (and I don't want to pedal up Beach Hill either, but if I did it would be a very low gear even on and electric bike). I don't think it really thinks about the gearing, at least not directly. I guess that is just based on keeping to a cadence that the motor likes.

~~~

If you are up that way don't miss Pipley Barn Cafe right on the Cotswold Way next to the Lansdown Golf Club. It's opening hours are likely to be pretty erratic for the next few months though.

One of my planned summer rides is the Lansdown route from Yate to Bathampton so I'll certainly look for the Cafe to stop at.


Darren