[trikes] steering design question

Thu Oct 28 11:21:05 PDT 2010

My wife was recently told she should use a wheelchair due to her ME. As keen cyclists we'd like to continue, and so I've been looking at designing an attachment for her chair which would convey it to something like a Vietnamese cyclo rickshaw 

http://www.rfleming.net/diarypics/Huecyclo2.jpg

Only thing I'm not certain about is the location of the steering pivot; should it be between the wheels like a kids soapbox kart, or behind the wheels like another conversion I've seen?

Any advice would be gratefully received.

Alex

Sent from Samsung mobile

trikes-request at bikelist.org wrote:

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>Today's Topics:
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>   1. Re: trikes Digest, Vol 72, Issue 6 (SerxnerLa at aol.com)
>   2. Re: Greenspeed GT3 gearing choices. (John Turvey) (John Turvey)
>   3. Re: trikes Digest, Vol 72, Issue 6 (John Turvey)
>   4. Re: Greenspeed GT3 gearing choices. (John Turvey) (Rob Hague)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Wed, 20 Oct 2010 15:34:44 EDT
>From: SerxnerLa at aol.com
>Subject: Re: [trikes] trikes Digest, Vol 72, Issue 6
>To: trikes at bikelist.org
>Message-ID: <71ee1.56fb8c9.39f09e54 at aol.com>
>Content-Type: text/plain; charset="US-ASCII"
>
>The Big Apple rear tire might give you a bit more ground clearance ifyou  
>need it
>
>
>------------------------------
>
>Message: 2
>Date: Wed, 20 Oct 2010 22:01:01 +0100
>From: John Turvey <johnturvey at onetel.com>
>Subject: Re: [trikes] Greenspeed GT3 gearing choices. (John Turvey)
>To: <trikes at bikelist.org>
>Message-ID: <2506FE92-DC8D-11DF-AADB-00306566DC3C at onetel.com>
>Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>My gear calculations use a wheel diameter of 16.2 inches (which, on 
>reflection, is probably for the original tyre the Micro came with, not 
>that for the 349 Scorchers) and the CORRECT size for the small 
>chainwheel which is 34 teeth, not 40 as I stated (that is the small 
>chainwheel on my Trice XXL), which gives a low gear of 17.2 inches - if 
>the diameter of the Scorcher is 17 inches, then my low gear is 18.1 
>inches and my high gear is 132.6 inches.
>
>There is no way to really re-dish the rear wheel - it is built like a 
>rear wheel for an upright, with the drive-side spokes nearer to 90 
>degrees from the rim than the off-side spokes. but the clearance 
>between the 'seat' stays and the Scorcher tyre is about 3mm on each 
>side - any change in dishing would not gain me much.
>
>My clearance problems are with the gear mech when the lower jockey 
>wheel is at the 6 o'clock position relative to the wheel - so moving 
>the chain idler to the right would not make any difference here as the 
>gear mech  and jockey wheel would not be moved to the right.
>
>My gear mech is a Sram X9 medium cage and there is not really enough 
>chain wrap as it is - when in the small chainring I have to remember to 
>only use the larger rear cogs. - if I forget I am in the small 
>chainring and run through the rear gears to the 11 tooth rear cog, the 
>rear gear mech folds so far that the chain runs against itself and 
>makes lots of noise!
>
>The only thing I have done to increase clearance is to remove part of 
>the left hand side of the derailleur cage - the lowest bit when at the 
>6 o'clock position, as this is the bit that gets bent and then shreds 
>the tyre - - on my original gear mech this bit fell off after several 
>bendings, and its absence made no difference to gear changing etc, so 
>when I replaced the mech, I removed this bit before using it.
>
>I  do wonder why other trike manufacturers persist with dished wheels - 
>the only reason for this is to provide heel clearance on traditional 
>upright 2-wheelers - so no reason at all to have dished wheels on 
>trikes (or, indeed, on 2-wheel recumbents).
>
>That reminds me - must have another dig at Jason P****** - he got a 2nd 
>hand Greenspeed and decided he did not want the hub gears, so had a new 
>rear wheel built - only after he installed it did he realise there is 
>no need to dish the rear wheel on a Greenspeed!
>
>John Turvey
>
>On Tuesday, October 19, 2010, at 11:49 PM, Ian Sims wrote:
>
>> Hi John,
>>         I was wondering how you came to the gearing range you quoted? 
>> By my
>> calculations you would have a bottom gear of 17x40/32 = 21, and even
>> 16x40/32 = 20. In top I would expect 17x52/11x1.65= 133.
>>
>> We certainly do not have any chain clearance problems with the 
>> Scorcher rear
>> tyres on the GTs. Maybe you could dish your rear wheel to the left, 
>> or/and
>> move the idler pulley out to the right to improve your chain 
>> clearance. Many
>> trike makers just use standard bicycle practice and dish the rear 
>> wheel to
>> the right, so that the tyre is centered about the dropouts or axle 
>> locknuts.
>> This weakens the rear wheel, and can give chain clearance problems, 
>> due to
>> the longer chain run on a recumbent. Whereas on a trike there is no 
>> need to
>> have the rear wheel on the centre line of the machine, as proven by the
>> Windcheatah, which runs quite a large offset. Thus you can build the 
>> rear
>> wheel symmetrically about the hub flanges, making it stronger and 
>> giving
>> more chain clearance, provided the frame is built to accommodate the 
>> tyre
>> offset. On a new trike I have built, I've discovered I still have chain
>> clearance in bottom gear, even with a 2.35" tyre :-)
>>
>> We are using the Shimano Tiagra rear derailleur on some of the GTs, and
>> there have been no ground clearance problems with this derailleur. It 
>> is not
>> supposed to cope with larger than a 27 t rear cog, but I've found if 
>> the
>> hanger is long enough there is no real problem with a 32, apart from a 
>> bit
>> more noise in bottom gear...
>>
>>
>> Regards, Ian
>>
>>
>>> I have an early Trice Micro which uses the same 16 inch wheel as the
>>> GT3 - it has a standard hub with 11 to 32 cassette, 52 and 40 teeth
>>> chainwheels and a Speed-drive, giving gears from 17 inches to 126
>>> inches, and uses a Sram medium cage gear mech.  The clearance below 
>>> the
>>> rear gear mech in some gears is minimal - a puncture in the rear wheel
>>> can mean the clearance is negative (I have replaced the rear mech once
>>> already as the original was wrecked as a result of punctures on high
>>> speed descents, and previously had replaced the lower jockey wheel in
>>> the original rear gear mech).  The other problem I have is that the
>>> clearance between the tyre and the rear mech is also minimal
>>> (especially as I use Greenspeed Scorcher tyres which are wider than
>>> most tyres) - after a rear wheel puncture, the cage on the rear gear
>>> mech can be bent, so using the lowest gear can quickly shred the side
>>> wall of the rear tyre (I have done this three times now - I keep
>>> telling myself to check the gear mech is not bent or misaligned, but
>>> forget occasionally - only when it IS bent or misaligned!)
>>>
>>> John Turvey
>
>
>
>------------------------------
>
>Message: 3
>Date: Wed, 20 Oct 2010 22:04:45 +0100
>From: John Turvey <johnturvey at onetel.com>
>Subject: Re: [trikes] trikes Digest, Vol 72, Issue 6
>To: trikes at bikelist.org
>Message-ID: <AA5EBFAE-DC8D-11DF-AADB-00306566DC3C at onetel.com>
>Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>See my previous reply re Ian Sims suggestions - frame clearance 
>limitations mean I cannot really use a tyre with a larger cross section 
>than the Greenspeed Scorcher.
>
>John Turvey
>
>
>On Wednesday, October 20, 2010, at 08:34 PM, SerxnerLa at aol.com wrote:
>
>> The Big Apple rear tire might give you a bit more ground clearance 
>> ifyou
>> need it
>> --
>> This message comes to you via the trikes at bikelist.org mailing list, 
>> sponsored by http://www.HuPI.org/
>> Visit http://bikelist.org/mailman/listinfo/trikes to manage your 
>> subscription.
>>
>
>
>
>------------------------------
>
>Message: 4
>Date: Thu, 21 Oct 2010 16:27:01 +0100
>From: Rob Hague <rob at wrhpv.com>
>Subject: Re: [trikes] Greenspeed GT3 gearing choices. (John Turvey)
>To: trikes at bikelist.org
>Message-ID: <D6841F88-ADDE-48D6-8BEE-A3B830BA246E at wrhpv.com>
>Content-Type: text/plain; charset=us-ascii
>
>We (BHPC racegoers) have been having a giggle at Mr Burrows as his latest race bike is the first one of his bikes that any of us can remember having two wheels inline... 
>
>Rob
>
>On 20 Oct 2010, at 22:01, John Turvey wrote:
>
>> My gear calculations use a wheel diameter of 16.2 inches (which, on reflection, is probably for the original tyre the Micro came with, not that for the 349 Scorchers) and the CORRECT size for the small chainwheel which is 34 teeth, not 40 as I stated (that is the small chainwheel on my Trice XXL), which gives a low gear of 17.2 inches - if the diameter of the Scorcher is 17 inches, then my low gear is 18.1 inches and my high gear is 132.6 inches.
>> 
>> There is no way to really re-dish the rear wheel - it is built like a rear wheel for an upright, with the drive-side spokes nearer to 90 degrees from the rim than the off-side spokes. but the clearance between the 'seat' stays and the Scorcher tyre is about 3mm on each side - any change in dishing would not gain me much.
>> 
>> My clearance problems are with the gear mech when the lower jockey wheel is at the 6 o'clock position relative to the wheel - so moving the chain idler to the right would not make any difference here as the gear mech  and jockey wheel would not be moved to the right.
>> 
>> My gear mech is a Sram X9 medium cage and there is not really enough chain wrap as it is - when in the small chainring I have to remember to only use the larger rear cogs. - if I forget I am in the small chainring and run through the rear gears to the 11 tooth rear cog, the rear gear mech folds so far that the chain runs against itself and makes lots of noise!
>> 
>> The only thing I have done to increase clearance is to remove part of the left hand side of the derailleur cage - the lowest bit when at the 6 o'clock position, as this is the bit that gets bent and then shreds the tyre - - on my original gear mech this bit fell off after several bendings, and its absence made no difference to gear changing etc, so when I replaced the mech, I removed this bit before using it.
>> 
>> I  do wonder why other trike manufacturers persist with dished wheels - the only reason for this is to provide heel clearance on traditional upright 2-wheelers - so no reason at all to have dished wheels on trikes (or, indeed, on 2-wheel recumbents).
>> 
>> That reminds me - must have another dig at Jason P****** - he got a 2nd hand Greenspeed and decided he did not want the hub gears, so had a new rear wheel built - only after he installed it did he realise there is no need to dish the rear wheel on a Greenspeed!
>> 
>> John Turvey
>> 
>> On Tuesday, October 19, 2010, at 11:49 PM, Ian Sims wrote:
>> 
>>> Hi John,
>>>        I was wondering how you came to the gearing range you quoted? By my
>>> calculations you would have a bottom gear of 17x40/32 = 21, and even
>>> 16x40/32 = 20. In top I would expect 17x52/11x1.65= 133.
>>> 
>>> We certainly do not have any chain clearance problems with the Scorcher rear
>>> tyres on the GTs. Maybe you could dish your rear wheel to the left, or/and
>>> move the idler pulley out to the right to improve your chain clearance. Many
>>> trike makers just use standard bicycle practice and dish the rear wheel to
>>> the right, so that the tyre is centered about the dropouts or axle locknuts.
>>> This weakens the rear wheel, and can give chain clearance problems, due to
>>> the longer chain run on a recumbent. Whereas on a trike there is no need to
>>> have the rear wheel on the centre line of the machine, as proven by the
>>> Windcheatah, which runs quite a large offset. Thus you can build the rear
>>> wheel symmetrically about the hub flanges, making it stronger and giving
>>> more chain clearance, provided the frame is built to accommodate the tyre
>>> offset. On a new trike I have built, I've discovered I still have chain
>>> clearance in bottom gear, even with a 2.35" tyre :-)
>>> 
>>> We are using the Shimano Tiagra rear derailleur on some of the GTs, and
>>> there have been no ground clearance problems with this derailleur. It is not
>>> supposed to cope with larger than a 27 t rear cog, but I've found if the
>>> hanger is long enough there is no real problem with a 32, apart from a bit
>>> more noise in bottom gear...
>>> 
>>> 
>>> Regards, Ian
>>> 
>>> 
>>>> I have an early Trice Micro which uses the same 16 inch wheel as the
>>>> GT3 - it has a standard hub with 11 to 32 cassette, 52 and 40 teeth
>>>> chainwheels and a Speed-drive, giving gears from 17 inches to 126
>>>> inches, and uses a Sram medium cage gear mech.  The clearance below the
>>>> rear gear mech in some gears is minimal - a puncture in the rear wheel
>>>> can mean the clearance is negative (I have replaced the rear mech once
>>>> already as the original was wrecked as a result of punctures on high
>>>> speed descents, and previously had replaced the lower jockey wheel in
>>>> the original rear gear mech).  The other problem I have is that the
>>>> clearance between the tyre and the rear mech is also minimal
>>>> (especially as I use Greenspeed Scorcher tyres which are wider than
>>>> most tyres) - after a rear wheel puncture, the cage on the rear gear
>>>> mech can be bent, so using the lowest gear can quickly shred the side
>>>> wall of the rear tyre (I have done this three times now - I keep
>>>> telling myself to check the gear mech is not bent or misaligned, but
>>>> forget occasionally - only when it IS bent or misaligned!)
>>>> 
>>>> John Turvey
>> 
>> --
>> This message comes to you via the trikes at bikelist.org mailing list, sponsored by http://www.HuPI.org/
>> Visit http://bikelist.org/mailman/listinfo/trikes to manage your subscription.
>
>
>
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>
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>End of trikes Digest, Vol 72, Issue 7
>*************************************
>